Changelog
*********


Python 3.10.17 final
====================

*Release date: 2025-04-08*


Security
--------

* gh-131809: Update bundled libexpat to 2.7.1

* gh-131261: Upgrade to libexpat 2.7.0

* gh-105704: When using "urllib.parse.urlsplit()" and
  "urllib.parse.urlparse()" host parsing would not reject domain names
  containing square brackets ("[" and "]"). Square brackets are only
  valid for IPv6 and IPvFuture hosts according to RFC 3986 Section
  3.2.2.

* gh-121284: Fix bug in the folding of rfc2047 encoded-words when
  flattening an email message using a modern email policy. Previously
  when an encoded-word was too long for a line, it would be decoded,
  split across lines, and re-encoded. But commas and other special
  characters in the original text could be left unencoded and
  unquoted. This could theoretically be used to spoof header lines
  using a carefully constructed encoded-word if the resulting rendered
  email was transmitted or re-parsed.

* gh-80222: Fix bug in the folding of quoted strings when flattening
  an email message using a modern email policy. Previously when a
  quoted string was folded so that it spanned more than one line, the
  surrounding quotes and internal escapes would be omitted. This could
  theoretically be used to spoof header lines using a carefully
  constructed quoted string if the resulting rendered email was
  transmitted or re-parsed.

* gh-119511: Fix a potential denial of service in the "imaplib"
  module. When connecting to a malicious server, it could cause an
  arbitrary amount of memory to be allocated. On many systems this is
  harmless as unused virtual memory is only a mapping, but if this hit
  a virtual address size limit it could lead to a "MemoryError" or
  other process crash. On unusual systems or builds where all
  allocated memory is touched and backed by actual ram or storage it
  could’ve consumed resources doing so until similarly crashing.


Library
-------

* gh-127257: In "ssl", system call failures that OpenSSL reports using
  "ERR_LIB_SYS" are now raised as "OSError".


Documentation
-------------

* gh-121277: Writers of CPython’s documentation can now use "next" as
  the version for the "versionchanged", "versionadded", "deprecated"
  directives.


Python 3.10.16 final
====================

*Release date: 2024-12-03*


Tests
-----

* gh-125041: Re-enable skipped tests for "zlib" on the s390x
  architecture: only skip checks of the compressed bytes, which can be
  different between zlib’s software implementation and the hardware-
  accelerated implementation.

* gh-109396: Fix "test_socket.test_hmac_sha1()" in FIPS mode. Use a
  longer key: FIPS mode requires at least of at least 112 bits. The
  previous key was only 32 bits. Patch by Victor Stinner.


Security
--------

* gh-126623: Upgrade libexpat to 2.6.4

* gh-122792: Changed IPv4-mapped "ipaddress.IPv6Address" to
  consistently use the mapped IPv4 address value for deciding
  properties. Properties which have their behavior fixed are
  "is_multicast", "is_reserved", "is_link_local", "is_global", and
  "is_unspecified".


Library
-------

* gh-124651: Properly quote template strings in "venv" activation
  scripts.

* gh-103848: Add checks to ensure that "[" bracketed "]" hosts found
  by "urllib.parse.urlsplit()" are of IPv6 or IPvFuture format.


Python 3.10.15 final
====================

*Release date: 2024-09-07*


Windows
-------

* gh-119690: Fixes data type confusion in audit events raised by
  "_winapi.CreateFile" and "_winapi.CreateNamedPipe".

* gh-116773: Fix instances of "<_overlapped.Overlapped object at
  0xXXX> still has pending operation at deallocation, the process may
  crash".


Tests
-----

* gh-112769: The tests now correctly compare zlib version when
  "zlib.ZLIB_RUNTIME_VERSION" contains non-integer suffixes. For
  example zlib-ng defines the version as "1.3.0.zlib-ng".

* gh-117187: Fix XML tests for vanilla Expat <2.6.0.

* gh-100454: Fix SSL tests CI for OpenSSL 3.1+


Security
--------

* gh-123678: Upgrade libexpat to 2.6.3

* gh-121957: Fixed missing audit events around interactive use of
  Python, now also properly firing for "python -i", as well as for
  "python -m asyncio". The event in question is "cpython.run_stdin".

* gh-122133: Authenticate the socket connection for the
  "socket.socketpair()" fallback on platforms where "AF_UNIX" is not
  available like Windows.

  Patch by Gregory P. Smith <greg@krypto.org> and Seth Larson
  <seth@python.org>. Reported by Ellie <el@horse64.org>

* gh-121285: Remove backtracking from tarfile header parsing for
  "hdrcharset", PAX, and GNU sparse headers.

* gh-118486: "os.mkdir()" on Windows now accepts *mode* of "0o700" to
  restrict the new directory to the current user. This fixes
  CVE-2024-4030 affecting "tempfile.mkdtemp()" in scenarios where the
  base temporary directory is more permissive than the default.

* gh-116741: Update bundled libexpat to 2.6.2


Library
-------

* gh-123693: Use platform-agnostic behavior when computing
  "zipfile.Path.name".

* gh-123270: Applied a more surgical fix for malformed payloads in
  "zipfile.Path" causing infinite loops (gh-122905) without breaking
  contents using legitimate characters.

* gh-123067: Fix quadratic complexity in parsing """-quoted cookie
  values with backslashes by "http.cookies".

* gh-122905: "zipfile.Path" objects now sanitize names from the
  zipfile.

* gh-121650: "email" headers with embedded newlines are now quoted on
  output. The "generator" will now refuse to serialize (write) headers
  that are unsafely folded or delimited; see
  "verify_generated_headers". (Contributed by Bas Bloemsaat and Petr
  Viktorin in gh-121650.)

* gh-113171: Fixed various false positives and false negatives in

  * "ipaddress.IPv4Address.is_private" (see these docs for details)

  * "ipaddress.IPv4Address.is_global"

  * "ipaddress.IPv6Address.is_private"

  * "ipaddress.IPv6Address.is_global"

  Also in the corresponding "ipaddress.IPv4Network" and
  "ipaddress.IPv6Network" attributes.

* gh-102988: "email.utils.getaddresses()" and
  "email.utils.parseaddr()" now return "('', '')" 2-tuples in more
  situations where invalid email addresses are encountered instead of
  potentially inaccurate values. Add optional *strict* parameter to
  these two functions: use "strict=False" to get the old behavior,
  accept malformed inputs. "getattr(email.utils,
  'supports_strict_parsing', False)" can be use to check if the
  *strict* paramater is available. Patch by Thomas Dwyer and Victor
  Stinner to improve the CVE-2023-27043 fix.

* gh-67693: Fix "urllib.parse.urlunparse()" and
  "urllib.parse.urlunsplit()" for URIs with path starting with
  multiple slashes and no authority. Based on patch by Ashwin
  Ramaswami.


Core and Builtins
-----------------

* gh-112275: A deadlock involving "pystate.c"’s "HEAD_LOCK" in
  "posixmodule.c" at fork is now fixed. Patch by ChuBoning based on
  previous Python 3.12 fix by Victor Stinner.


Python 3.10.14 final
====================

*Release date: 2024-03-19*


Security
--------

* gh-115398: Allow controlling Expat >=2.6.0 reparse deferral
  (CVE-2023-52425) by adding five new methods:

  * "xml.etree.ElementTree.XMLParser.flush()"

  * "xml.etree.ElementTree.XMLPullParser.flush()"

  * "xml.parsers.expat.xmlparser.GetReparseDeferralEnabled()"

  * "xml.parsers.expat.xmlparser.SetReparseDeferralEnabled()"

  * "xml.sax.expatreader.ExpatParser.flush()"

* gh-115399: Update bundled libexpat to 2.6.0

* gh-114572: "ssl.SSLContext.cert_store_stats()" and
  "ssl.SSLContext.get_ca_certs()" now correctly lock access to the
  certificate store, when the "ssl.SSLContext" is shared across
  multiple threads.

* gh-113659: Skip ".pth" files with names starting with a dot or
  hidden file attribute.


Core and Builtins
-----------------

* gh-102388: Fix a bug where "iso2022_jp_3" and "iso2022_jp_2004"
  codecs read out of bounds


Library
-------

* gh-115197: "urllib.request" no longer resolves the hostname before
  checking it against the system’s proxy bypass list on macOS and
  Windows.

* gh-115133: Fix tests for "XMLPullParser" with Expat 2.6.0.

* gh-81194: Fix a crash in "socket.if_indextoname()" with specific
  value (UINT_MAX). Fix an integer overflow in
  "socket.if_indextoname()" on 64-bit non-Windows platforms.

* gh-109858: Protect "zipfile" from “quoted-overlap” zipbomb. It now
  raises BadZipFile when try to read an entry that overlaps with other
  entry or central directory.

* gh-91133: Fix a bug in "tempfile.TemporaryDirectory" cleanup, which
  now no longer dereferences symlinks when working around file system
  permission errors.


Documentation
-------------

* gh-115399: Document CVE-2023-52425 of Expat <2.6.0 under “XML
  vulnerabilities”.


Windows
-------

* gh-111239: Update Windows builds to use zlib v1.3.1.

* gh-109991: Windows builds now use OpenSSL 1.1.1w. Note that OpenSSL
  1.1 has reached its end of life and no future fixes will be made,
  and this version of Python is no longer receiving maintenance fixes
  and will not be updated to OpenSSL 3.0.


Tools/Demos
-----------

* gh-109991: Update GitHub CI workflows to use OpenSSL 3.0.11 and
  multissltests to use 1.1.1w, 3.0.11, and 3.1.3.


Python 3.10.13 final
====================

*Release date: 2023-08-24*


Security
--------

* gh-108310: Fixed an issue where instances of "ssl.SSLSocket" were
  vulnerable to a bypass of the TLS handshake and included protections
  (like certificate verification) and treating sent unencrypted data
  as if it were post-handshake TLS encrypted data.  Security issue
  reported as CVE-2023-40217 by Aapo Oksman. Patch by Gregory P.
  Smith.


Library
-------

* gh-107845: "tarfile.data_filter()" now takes the location of
  symlinks into account when determining their target, so it will no
  longer reject some valid tarballs with
  "LinkOutsideDestinationError".


Tools/Demos
-----------

* gh-107565: Update multissltests and GitHub CI workflows to use
  OpenSSL 1.1.1v, 3.0.10, and 3.1.2.


C API
-----

* gh-99612: Fix "PyUnicode_DecodeUTF8Stateful()" for ASCII-only data:
  "*consumed" was not set.


Python 3.10.12 final
====================

*Release date: 2023-06-06*


Security
--------

* gh-103142: The version of OpenSSL used in our binary builds has been
  upgraded to 1.1.1u to address several CVEs.

* gh-99889: Fixed a security in flaw in "uu.decode()" that could allow
  for directory traversal based on the input if no "out_file" was
  specified.

* gh-104049: Do not expose the local on-disk location in directory
  indexes produced by "http.client.SimpleHTTPRequestHandler".

* gh-102153: "urllib.parse.urlsplit()" now strips leading C0 control
  and space characters following the specification for URLs defined by
  WHATWG in response to CVE-2023-24329. Patch by Illia Volochii.


Library
-------

* gh-103935: Use "io.open_code()" for files to be executed instead of
  raw "open()"

* gh-102953: The extraction methods in "tarfile", and
  "shutil.unpack_archive()", have a new a *filter* argument that
  allows limiting tar features than may be surprising or dangerous,
  such as creating files outside the destination directory. See
  Extraction filters for details.


Documentation
-------------

* gh-89412: Add missing documentation for the "end_lineno" and
  "end_offset" attributes of the "traceback.TracebackException" class.


Build
-----

* gh-103262: Fixes Windows installer build to work with latest
  compilers.


Python 3.10.11 final
====================

*Release date: 2023-04-04*


Security
--------

* gh-101727: Updated the OpenSSL version used in Windows and macOS
  binary release builds to 1.1.1t to address CVE-2023-0286,
  CVE-2022-4303, and CVE-2022-4303 per the OpenSSL 2023-02-07 security
  advisory.

* gh-101283: "subprocess.Popen" now uses a safer approach to find
  "cmd.exe" when launching with "shell=True". Patch by Eryk Sun, based
  on a patch by Oleg Iarygin.


Core and Builtins
-----------------

* gh-102416: Do not memoize incorrectly automatically generated loop
  rules in the parser. Patch by Pablo Galindo.

* gh-102356: Fix a bug that caused a crash when deallocating deeply
  nested filter objects. Patch by Marta Gómez Macías.

* gh-102397: Fix segfault from race condition in signal handling
  during garbage collection. Patch by Kumar Aditya.

* gh-102126: Fix deadlock at shutdown when clearing thread states if
  any finalizer tries to acquire the runtime head lock. Patch by Kumar
  Aditya.

* gh-102027: Fix SSE2 and SSE3 detection in "_blake2" internal module.
  Patch by Max Bachmann.

* gh-101967: Fix possible segfault in
  "positional_only_passed_as_keyword" function, when new list created.

* gh-101765: Fix SystemError / segmentation fault in iter "__reduce__"
  when internal access of "builtins.__dict__" keys mutates the iter
  object.


Library
-------

* gh-102947: Improve traceback when "dataclasses.fields()" is called
  on a non-dataclass. Patch by Alex Waygood

* gh-101979: Fix a bug where parentheses in the "metavar" argument to
  "argparse.ArgumentParser.add_argument()" were dropped. Patch by
  Yeojin Kim.

* gh-102179: Fix "os.dup2()" error message for negative fds.

* gh-101961: For the binary mode, "fileinput.hookcompressed()" doesn’t
  set the "encoding" value even if the value is "None". Patch by
  Gihwan Kim.

* gh-101936: The default value of "fp" becomes "io.BytesIO" if
  "HTTPError" is initialized without a designated "fp" parameter.
  Patch by Long Vo.

* gh-101566: In zipfile, apply fix for extractall on the underlying
  zipfile after being wrapped in "Path".

* gh-101997: Upgrade pip wheel bundled with ensurepip (pip 23.0.1)

* gh-101892: Callable iterators no longer raise "SystemError" when the
  callable object exhausts the iterator but forgets to either return a
  sentinel value or raise "StopIteration".

* gh-97786: Fix potential undefined behaviour in corner cases of
  floating-point-to-time conversions.

* gh-101517: Fixed bug where "bdb" looks up the source line with
  "linecache" with a "lineno=None", which causes it to fail with an
  unhandled exception.

* gh-101673: Fix a "pdb" bug where "ll" clears the changes to local
  variables.

* gh-96931: Fix incorrect results from
  "ssl.SSLSocket.shared_ciphers()"

* gh-88233: Correctly preserve “extra” fields in "zipfile" regardless
  of their ordering relative to a zip64 “extra.”

* gh-95495: When built against OpenSSL 3.0, the "ssl" module had a bug
  where it reported unauthenticated EOFs (i.e. without close_notify)
  as a clean TLS-level EOF. It now raises "SSLEOFError", matching the
  behavior in previous versions of OpenSSL. The "options" attribute on
  "SSLContext" also no longer includes "OP_IGNORE_UNEXPECTED_EOF" by
  default. This option may be set to specify the previous OpenSSL 3.0
  behavior.

* gh-94440: Fix a "concurrent.futures.process" bug where
  "ProcessPoolExecutor" shutdown could hang after a future has been
  quickly submitted and canceled.


Documentation
-------------

* gh-103112: Add docstring to "http.client.HTTPResponse.read()" to fix
  "pydoc" output.

* gh-85417: Update "cmath" documentation to clarify behaviour on
  branch cuts.

* gh-97725: Fix "asyncio.Task.print_stack()" description for
  "file=None". Patch by Oleg Iarygin.


Tests
-----

* gh-102980: Improve test coverage on "pdb".

* gh-102537: Adjust the error handling strategy in
  "test_zoneinfo.TzPathTest.python_tzpath_context". Patch by Paul
  Ganssle.

* gh-101377: Improved test_locale_calendar_formatweekday of calendar.


Build
-----

* gh-102711: Fix "-Wstrict-prototypes" compiler warnings.


Windows
-------

* gh-101759: Update Windows installer to SQLite 3.40.1.

* gh-101614: Correctly handle extensions built against debug binaries
  that reference "python3_d.dll".


macOS
-----

* gh-103207: Add instructions to the macOS installer welcome display
  on how to workaround the macOS 13 Ventura “The installer encountered
  an error” failure.

* gh-101759: Update macOS installer to SQLite 3.40.1.

* gh-87235: On macOS "python3 /dev/fd/9 9</path/to/script.py" failed
  for any script longer than a couple of bytes.


Python 3.10.10 final
====================

*Release date: 2023-02-07*


Core and Builtins
-----------------

* gh-101400: Fix wrong lineno in exception message on "continue" or
  "break" which are not in a loop. Patch by Dong-hee Na.

* gh-101372: Fix "is_normalized()" to properly handle the UCD 3.2.0
  cases. Patch by Dong-hee Na.

* gh-101046: Fix a possible memory leak in the parser when raising
  "MemoryError". Patch by Pablo Galindo

* gh-100942: Fixed segfault in property.getter/setter/deleter that
  occurred when a property subclass overrode the "__new__" method to
  return a non-property instance.

* gh-100892: Fix race while iterating over thread states in clearing
  "threading.local". Patch by Kumar Aditya.

* gh-100776: Fix misleading default value in "input()"’s
  "__text_signature__".

* gh-100374: Fix incorrect result and delay in "socket.getfqdn()".
  Patch by Dominic Socular.

* gh-100050: Honor existing errors obtained when searching for
  mismatching parentheses in the tokenizer. Patch by Pablo Galindo

* bpo-32782: "ctypes" arrays of length 0 now report a correct itemsize
  when a "memoryview" is constructed from them, rather than always
  giving a value of 0.


Library
-------

* gh-100795: Avoid potential unexpected "freeaddrinfo" call (double
  free) in "socket" when when a libc "getaddrinfo()" implementation
  leaves garbage in an output pointer when returning an error.
  Original patch by Sergey G. Brester.

* gh-101143: Remove unused references to "TimerHandle" in
  "asyncio.base_events.BaseEventLoop._add_callback".

* gh-101144: Make "zipfile.Path.open()" and "zipfile.Path.read_text()"
  also accept "encoding" as a positional argument. This was the
  behavior in Python 3.9 and earlier. Earlier 3.10 versions had a
  regression where supplying it as a positional argument would lead to
  a "TypeError".

* gh-100573: Fix a Windows "asyncio" bug with named pipes where a
  client doing "os.stat()" on the pipe would cause an error in the
  server that disabled serving future requests.

* gh-90104: Avoid RecursionError on "repr" if a dataclass field
  definition has a cyclic reference.

* gh-100689: Fix crash in "pyexpat" by statically allocating
  "PyExpat_CAPI" capsule.

* gh-100740: Fix "unittest.mock.Mock" not respecting the spec for
  attribute names prefixed with "assert".

* gh-86508: Fix "asyncio.open_connection()" to skip binding to local
  addresses of different family. Patch by Kumar Aditya.

* gh-100287: Fix the interaction of "unittest.mock.seal()" with
  "unittest.mock.AsyncMock".

* gh-100474: "http.server" now checks that an index page is actually a
  regular file before trying to serve it.  This avoids issues with
  directories named "index.html".

* gh-100160: Remove any deprecation warnings in
  "asyncio.get_event_loop()". They are deferred to Python 3.12.

* gh-99952: Fix a reference undercounting issue in "ctypes.Structure"
  with "from_param()" results larger than a C pointer.

* gh-98778: Update "HTTPError" to be initialized properly, even if the
  "fp" is "None". Patch by Dong-hee Na.

* gh-83035: Fix "inspect.getsource()" handling of decorator calls with
  nested parentheses.

* gh-99240: Fix double-free bug in Argument Clinic "str_converter" by
  extracting memory clean up to a new "post_parsing" section.

* gh-85267: Several improvements to "inspect.signature()"’s handling
  of "__text_signature". - Fixes a case where "inspect.signature()"
  dropped parameters - Fixes a case where "inspect.signature()" raised
  "tokenize.TokenError" - Allows "inspect.signature()" to understand
  defaults involving binary operations of constants -
  "inspect.signature()" is documented as only raising "TypeError" or
  "ValueError", but sometimes raised "RuntimeError". These cases now
  raise "ValueError" - Removed a dead code path

* gh-96192: Fix handling of "bytes" *path-like objects* in
  "os.ismount()".

* bpo-44817: Ignore WinError 53 (ERROR_BAD_NETPATH), 65
  (ERROR_NETWORK_ACCESS_DENIED) and 161 (ERROR_BAD_PATHNAME) when
  using ntpath.realpath().

* bpo-40447: Accept "os.PathLike" (such as "pathlib.Path") in the
  "stripdir" arguments of "compileall.compile_file()" and
  "compileall.compile_dir()".

* bpo-36880: Fix a reference counting issue when a "ctypes" callback
  with return type "py_object" returns "None", which could cause
  crashes.


Documentation
-------------

* gh-100616: Document existing "attr" parameter to
  "curses.window.vline()" function in "curses".

* gh-100472: Remove claim in documentation that the "stripdir",
  "prependdir" and "limit_sl_dest" parameters of
  "compileall.compile_dir()" and "compileall.compile_file()" could be
  "bytes".


Tests
-----

* gh-101334: "test_tarfile" has been updated to pass when run as a
  high UID.

* gh-96002: Add functional test for Argument Clinic.


Build
-----

* gh-101522: Allow overriding Windows dependencies versions and paths
  using MSBuild properties.


Windows
-------

* gh-82052: Fixed an issue where writing more than 32K of Unicode
  output to the console screen in one go can result in mojibake.

* gh-100180: Update Windows installer to OpenSSL 1.1.1s

* bpo-43984: "winreg.SetValueEx()" now leaves the target value
  untouched in the case of conversion errors. Previously, "-1" would
  be written in case of such errors.


macOS
-----

* gh-100180: Update macOS installer to OpenSSL 1.1.1s


C API
-----

* gh-99240: In argument parsing, after deallocating newly allocated
  memory, reset its pointer to NULL.


Python 3.10.9 final
===================

*Release date: 2022-12-06*


Security
--------

* gh-100001: "python -m http.server" no longer allows terminal control
  characters sent within a garbage request to be printed to the stderr
  server log.

  This is done by changing the "http.server" "BaseHTTPRequestHandler"
  ".log_message" method to replace control characters with a "\xHH"
  hex escape before printing.

* gh-87604: Avoid publishing list of active per-interpreter audit
  hooks via the "gc" module

* gh-98433: The IDNA codec decoder used on DNS hostnames by "socket"
  or "asyncio" related name resolution functions no longer involves a
  quadratic algorithm. This prevents a potential CPU denial of service
  if an out-of-spec excessive length hostname involving bidirectional
  characters were decoded. Some protocols such as "urllib" http "3xx"
  redirects potentially allow for an attacker to supply such a name.

* gh-98739: Update bundled libexpat to 2.5.0

* gh-98517: Port XKCP’s fix for the buffer overflows in SHA-3
  (CVE-2022-37454).

* gh-97514: On Linux the "multiprocessing" module returns to using
  filesystem backed unix domain sockets for communication with the
  *forkserver* process instead of the Linux abstract socket namespace.
  Only code that chooses to use the “forkserver” start method is
  affected.

  Abstract sockets have no permissions and could allow any user on the
  system in the same network namespace (often the whole system) to
  inject code into the multiprocessing *forkserver* process. This was
  a potential privilege escalation. Filesystem based socket
  permissions restrict this to the *forkserver* process user as was
  the default in Python 3.8 and earlier.

  This prevents Linux CVE-2022-42919.


Core and Builtins
-----------------

* gh-99578: Fix a reference bug in "_imp.create_builtin()" after the
  creation of the first sub-interpreter for modules "builtins" and
  "sys". Patch by Victor Stinner.

* gh-99581: Fixed a bug that was causing a buffer overflow if the
  tokenizer copies a line missing the newline caracter from a file
  that is as long as the available tokenizer buffer. Patch by Pablo
  galindo

* gh-96055: Update "faulthandler" to emit an error message with the
  proper unexpected signal number. Patch by Dong-hee Na.

* gh-98852: Fix subscription of "types.GenericAlias" instances
  containing bare generic types: for example "tuple[A, T][int]", where
  "A" is a generic type, and "T" is a type variable.

* gh-98415: Fix detection of MAC addresses for "uuid" on certain OSs.
  Patch by Chaim Sanders

* gh-92119: Print exception class name instead of its string
  representation when raising errors from "ctypes" calls.

* gh-93696: Allow "pdb" to locate source for frozen modules in the
  standard library.

* bpo-31718: Raise "ValueError" instead of "SystemError" when methods
  of uninitialized "io.IncrementalNewlineDecoder" objects are called.
  Patch by Oren Milman.

* bpo-38031: Fix a possible assertion failure in "io.FileIO" when the
  opener returns an invalid file descriptor.


Library
-------

* gh-100001: Also escape s in the http.server
  BaseHTTPRequestHandler.log_message so that it is technically
  possible to parse the line and reconstruct what the original data
  was.  Without this a xHH is ambiguious as to if it is a hex
  replacement we put in or the characters r”x” came through in the
  original request line.

* gh-93453: "asyncio.get_event_loop()" now only emits a deprecation
  warning when a new event loop was created implicitly. It no longer
  emits a deprecation warning if the current event loop was set.

* gh-51524: Fix bug when calling trace.CoverageResults with valid
  infile.

* gh-99645: Fix a bug in handling class cleanups in
  "unittest.TestCase".  Now "addClassCleanup()" uses separate lists
  for different "TestCase" subclasses, and "doClassCleanups()" only
  cleans up the particular class.

* gh-97001: Release the GIL when calling termios APIs to avoid
  blocking threads.

* gh-99341: Fix "ast.increment_lineno()" to also cover
  "ast.TypeIgnore" when changing line numbers.

* gh-74044: Fixed bug where "inspect.signature()" reported incorrect
  arguments for decorated methods.

* gh-99275: Fix "SystemError" in "ctypes" when exception was not set
  during "__initsubclass__".

* gh-99155: Fix "statistics.NormalDist" pickle with "0" and "1"
  protocols.

* gh-99134: Update the bundled copy of pip to version 22.3.1.

* gh-99130: Apply bugfixes from importlib_metadata 4.11.4, namely: In
  "PathDistribution._name_from_stem", avoid including parts of the
  extension in the result. In "PathDistribution._normalized_name",
  ensure names loaded from the stem of the filename are also
  normalized, ensuring duplicate entry points by packages varying only
  by non-normalized name are hidden.

* gh-83004: Clean up refleak on failed module initialisation in
  "_zoneinfo"

* gh-83004: Clean up refleaks on failed module initialisation in in
  "_pickle"

* gh-83004: Clean up refleak on failed module initialisation in "_io".

* gh-98897: Fix memory leak in "math.dist()" when both points don’t
  have the same dimension. Patch by Kumar Aditya.

* gh-98793: Fix argument typechecks in "_overlapped.WSAConnect()" and
  "_overlapped.Overlapped.WSASendTo()" functions.

* gh-98740: Fix internal error in the "re" module which in very rare
  circumstances prevented compilation of a regular expression
  containing a conditional expression without the “else” branch.

* gh-98703: Fix "asyncio.StreamWriter.drain()" to call
  "protocol.connection_lost" callback only once on Windows.

* gh-98624: Add a mutex to unittest.mock.NonCallableMock to protect
  concurrent access to mock attributes.

* gh-89237: Fix hang on Windows in "subprocess.wait_closed()" in
  "asyncio" with "ProactorEventLoop". Patch by Kumar Aditya.

* gh-98458: Fix infinite loop in unittest when a self-referencing
  chained exception is raised

* gh-97928: "tkinter.Text.count()" raises now an exception for options
  starting with “-” instead of silently ignoring them.

* gh-97966: On "uname_result", restored expectation that "_fields" and
  "_asdict" would include all six properties including "processor".

* gh-98331: Update the bundled copies of pip and setuptools to
  versions 22.3 and 65.5.0 respectively.

* gh-96035: Fix bug in "urllib.parse.urlparse()" that causes certain
  port numbers containing whitespace, underscores, plus and minus
  signs, or non-ASCII digits to be incorrectly accepted.

* gh-98251: Allow "venv" to pass along "PYTHON*" variables to
  "ensurepip" and "pip" when they do not impact path resolution

* gh-98178: On macOS, fix a crash in "syslog.syslog()" in multi-
  threaded applications. On macOS, the libc "syslog()" function is not
  thread-safe, so "syslog.syslog()" no longer releases the GIL to call
  it. Patch by Victor Stinner.

* gh-96151: Allow "BUILTINS" to be a valid field name for frozen
  dataclasses.

* gh-98086: Make sure "patch.dict()" can be applied on async
  functions.

* gh-88863: To avoid apparent memory leaks when
  "asyncio.open_connection()" raises, break reference cycles generated
  by local exception and future instances (which has exception
  instance as its member var). Patch by Dong Uk, Kang.

* gh-93858: Prevent error when activating venv in nested fish
  instances.

* bpo-46364: Restrict use of sockets instead of pipes for stdin of
  subprocesses created by "asyncio" to AIX platform only.

* bpo-38523: "shutil.copytree()" now applies the
  *ignore_dangling_symlinks* argument recursively.

* bpo-36267: Fix IndexError in "argparse.ArgumentParser" when a
  "store_true" action is given an explicit argument.


Documentation
-------------

* gh-92892: Document that calling variadic functions with ctypes
  requires special care on macOS/arm64 (and possibly other platforms).


Tests
-----

* gh-99892: Skip test_normalization() of test_unicodedata if it fails
  to download NormalizationTest.txt file from pythontest.net. Patch by
  Victor Stinner.

* bpo-34272: Some C API tests were moved into the new
  Lib/test/test_capi/ directory.


Build
-----

* gh-99086: Fix "-Wimplicit-int", "-Wstrict-prototypes", and
  "-Wimplicit-function-declaration" compiler warnings in **configure**
  checks.

* gh-99086: Fix "-Wimplicit-int" compiler warning in **configure**
  check for "PTHREAD_SCOPE_SYSTEM".

* gh-97731: Specify the full path to the source location for "make
  docclean" (needed for cross-builds).

* gh-98671: Fix "NO_MISALIGNED_ACCESSES" being not defined for the
  SHA3 extension when "HAVE_ALIGNED_REQUIRED" is set. Allowing builds
  on hardware that unaligned memory accesses are not allowed.


Windows
-------

* gh-99345: Use faster initialization functions to detect install
  location for Windows Store package

* gh-98689: Update Windows builds to zlib v1.2.13.  v1.2.12 has
  CVE-2022-37434, but the vulnerable "inflateGetHeader" API is not
  used by Python.

* gh-94328: Update Windows installer to use SQLite 3.39.4.

* bpo-40882: Fix a memory leak in
  "multiprocessing.shared_memory.SharedMemory" on Windows.


macOS
-----

* gh-94328: Update macOS installer to SQLite 3.39.4.


IDLE
----

* gh-97527: Fix a bug in the previous bugfix that caused IDLE to not
  start when run with 3.10.8, 3.12.0a1, and at least Microsoft Python
  3.10.2288.0 installed without the Lib/test package.  3.11.0 was
  never affected.


Tools/Demos
-----------

* gh-95731: Fix handling of module docstrings in
  "Tools/i18n/pygettext.py".


Python 3.10.8 final
===================

*Release date: 2022-10-11*


Security
--------

* gh-97616: Fix multiplying a list by an integer ("list *= int"):
  detect the integer overflow when the new allocated length is close
  to the maximum size. Issue reported by Jordan Limor.  Patch by
  Victor Stinner.

* gh-97612: Fix a shell code injection vulnerability in the "get-
  remote-certificate.py" example script. The script no longer uses a
  shell to run "openssl" commands. Issue reported and initial fix by
  Caleb Shortt. Patch by Victor Stinner.

* gh-68966: The deprecated mailcap module now refuses to inject unsafe
  text (filenames, MIME types, parameters) into shell commands.
  Instead of using such text, it will warn and act as if a match was
  not found (or for test commands, as if the test failed).


Core and Builtins
-----------------

* gh-96078: "os.sched_yield()" now release the GIL while calling
  sched_yield(2). Patch by Dong-hee Na.

* gh-97943: Bugfix: "PyFunction_GetAnnotations()" should return a
  borrowed reference. It was returning a new reference.

* gh-97591: Fixed a missing incref/decref pair in
  "Exception.__setstate__()". Patch by Ofey Chan.

* gh-96848: Fix command line parsing: reject "-X int_max_str_digits"
  option with no value (invalid) when the "PYTHONINTMAXSTRDIGITS"
  environment variable is set to a valid limit. Patch by Victor
  Stinner.

* gh-95921: Fix overly-broad source position information for chained
  comparisons used as branching conditions.

* gh-96821: Fix undefined behaviour in "_testcapimodule.c".

* gh-95778: When "ValueError" is raised if an integer is larger than
  the limit, mention the "sys.set_int_max_str_digits()" function in
  the error message. Patch by Victor Stinner.

* gh-96387: At Python exit, sometimes a thread holding the GIL can
  wait forever for a thread (usually a daemon thread) which requested
  to drop the GIL, whereas the thread already exited. To fix the race
  condition, the thread which requested the GIL drop now resets its
  request before exiting. Issue discovered and analyzed by Mingliang
  ZHAO. Patch by Victor Stinner.

* gh-96864: Fix a possible assertion failure, fatal error, or
  "SystemError" if a line tracing event raises an exception while
  opcode tracing is enabled.

* gh-96678: Fix undefined behaviour in C code of null pointer
  arithmetic.

* gh-96641: Do not expose "KeyWrapper" in "_functools".

* gh-96611: When loading a file with invalid UTF-8 inside a multi-line
  string, a correct SyntaxError is emitted.

* gh-95196: Disable incorrect pickling of the C implemented
  classmethod descriptors.

* gh-96352: Fix "AttributeError" missing "name" and "obj" attributes
  in "object.__getattribute__()". Patch by Philip Georgi.

* bpo-42316: Document some places where an assignment expression needs
  parentheses.


Library
-------

* gh-87730: Wrap network errors consistently in urllib FTP support, so
  the test suite doesn’t fail when a network is available but the
  public internet is not reachable.

* gh-97825: Fixes "AttributeError" when "subprocess.check_output()" is
  used with argument "input=None" and either of the arguments
  *encoding* or *errors* are used.

* gh-96827: Avoid spurious tracebacks from "asyncio" when default
  executor cleanup is delayed until after the event loop is closed
  (e.g. as the result of a keyboard interrupt).

* gh-97592: Avoid a crash in the C version of
  "asyncio.Future.remove_done_callback()" when an evil argument is
  passed.

* gh-97639: Remove "tokenize.NL" check from "tabnanny".

* gh-97545: Make Semaphore run faster.

* gh-73588: Fix generation of the default name of
  "tkinter.Checkbutton". Previously, checkbuttons in different parent
  widgets could have the same short name and share the same state if
  arguments “name” and “variable” are not specified. Now they are
  globally unique.

* gh-97005: Update bundled libexpat to 2.4.9

* gh-85760: Fix race condition in "asyncio" where "process_exited()"
  called before the "pipe_data_received()" leading to inconsistent
  output. Patch by Kumar Aditya.

* gh-96819: Fixed check in "multiprocessing.resource_tracker" that
  guarantees that the length of a write to a pipe is not greater than
  "PIPE_BUF".

* gh-96741: Corrected type annotation for dataclass attribute
  "pstats.FunctionProfile.ncalls" to be "str".

* gh-96652: Fix the faulthandler implementation of
  "faulthandler.register(signal, chain=True)" if the "sigaction()"
  function is not available: don’t call the previous signal handler if
  it’s NULL. Patch by Victor Stinner.

* gh-96073: In "inspect", fix overeager replacement of “"typing."” in
  formatting annotations.

* gh-90467: Fix "asyncio.streams.StreamReaderProtocol" to keep a
  strong reference to the created task, so that it’s not garbage
  collected

* gh-96052: Fix handling compiler warnings (SyntaxWarning and
  DeprecationWarning) in "codeop.compile_command()" when checking for
  incomplete input. Previously it emitted warnings and raised a
  SyntaxError. Now it always returns "None" for incomplete input
  without emitting any warnings.

* gh-91212: Fixed flickering of the turtle window when the tracer is
  turned off. Patch by Shin-myoung-serp.

* gh-74116: Allow "asyncio.StreamWriter.drain()" to be awaited
  concurrently by multiple tasks. Patch by Kumar Aditya.

* gh-90155: Fix broken "asyncio.Semaphore" when acquire is cancelled.

* gh-92986: Fix "ast.unparse()" when "ImportFrom.level" is None

* gh-91539: Improve performance of
  "urllib.request.getproxies_environment" when there are many
  environment variables


Documentation
-------------

* gh-97741: Fix "!" in c domain ref target syntax via a "conf.py"
  patch, so it works as intended to disable ref target resolution.

* gh-95588: Clarified the conflicting advice given in the "ast"
  documentation about "ast.literal_eval()" being “safe” for use on
  untrusted input while at the same time warning that it can crash the
  process. The latter statement is true and is deemed unfixable
  without a large amount of work unsuitable for a bugfix. So we keep
  the warning and no longer claim that "literal_eval" is safe.

* gh-93031: Update tutorial introduction output to use 3.10+
  SyntaxError invalid range.


Build
-----

* gh-96729: Ensure that Windows releases built with
  "Tools\msi\buildrelease.bat" are upgradable to and from official
  Python releases.


Windows
-------

* gh-97728: Fix possible crashes caused by the use of uninitialized
  variables when pass invalid arguments in "os.system()" on Windows
  and in Windows-specific modules (like "winreg").

* gh-90989: Clarify some text in the Windows installer.

* gh-96577: Fixes a potential buffer overrun in "msilib".


macOS
-----

* gh-97897: The macOS 13 SDK includes support for the "mkfifoat" and
  "mknodat" system calls. Using the "dir_fd" option with either
  "os.mkfifo()" or "os.mknod()" could result in a segfault if cpython
  is built with the macOS 13 SDK but run on an earlier version of
  macOS. Prevent this by adding runtime support for detection of these
  system calls (“weaklinking”) as is done for other newer syscalls on
  macOS.


Python 3.10.7 final
===================

*Release date: 2022-09-05*


Security
--------

* gh-95778: Converting between "int" and "str" in bases other than 2
  (binary), 4, 8 (octal), 16 (hexadecimal), or 32 such as base 10
  (decimal) now raises a "ValueError" if the number of digits in
  string form is above a limit to avoid potential denial of service
  attacks due to the algorithmic complexity. This is a mitigation for
  CVE-2020-10735.

  This new limit can be configured or disabled by environment
  variable, command line flag, or "sys" APIs. See the integer string
  conversion length limitation documentation.  The default limit is
  4300 digits in string form.

  Patch by Gregory P. Smith [Google] and Christian Heimes [Red Hat]
  with feedback from Victor Stinner, Thomas Wouters, Steve Dower, Ned
  Deily, and Mark Dickinson.


Core and Builtins
-----------------

* gh-96187: Fixed a bug that caused "_PyCode_GetExtra" to return
  garbage for negative indexes. Patch by Pablo Galindo

* gh-95876: Fix format string in "_PyPegen_raise_error_known_location"
  that can lead to memory corruption on some 64bit systems. The
  function was building a tuple with "i" (int) instead of "n"
  (Py_ssize_t) for Py_ssize_t arguments.

* gh-95605: Fix misleading contents of error message when converting
  an all-whitespace string to "float".

* gh-93592: "coroutine.throw()" now properly initializes the
  "frame.f_back" when resuming a stack of coroutines. This allows e.g.
  "traceback.print_stack()" to work correctly when an exception (such
  as "CancelledError") is thrown into a coroutine.

* gh-94996: "ast.parse()" will no longer parse function definitions
  with positional-only params when passed "feature_version" less than
  "(3, 8)". Patch by Shantanu Jain.


Library
-------

* gh-68163: Correct conversion of "numbers.Rational"’s to "float".

* gh-96159: Fix a performance regression in logging
  TimedRotatingFileHandler. Only check for special files when the
  rollover time has passed.

* gh-96175: Fix unused "localName" parameter in the "Attr" class in
  "xml.dom.minidom".

* gh-95609: Update bundled pip to 22.2.2.

* gh-95231: Fail gracefully if "EPERM" or "ENOSYS" is raised when
  loading "crypt" methods. This may happen when trying to load "MD5"
  on a Linux kernel with FIPS (Federal Information Processing
  Standard) enabled.


Documentation
-------------

* gh-96098: Improve discoverability of the higher level
  concurrent.futures module by providing clearer links from the lower
  level threading and multiprocessing modules.

* gh-95789: Update the default RFC base URL from deprecated
  tools.ietf.org to datatracker.ietf.org

* gh-91207: Fix stylesheet not working in Windows CHM htmlhelp docs.
  Contributed by C.A.M. Gerlach.

* bpo-47115: The documentation now lists which members of C structs
  are part of the Limited API/Stable ABI.


Tests
-----

* gh-95243: Mitigate the inherent race condition from using
  find_unused_port() in testSockName() by trying to find an unused
  port a few times before failing. Patch by Ross Burton.


Build
-----

* gh-94682: Build and test with OpenSSL 1.1.1q


IDLE
----

* gh-65802: Document handling of extensions in Save As dialogs.

* gh-95191: Include prompts when saving Shell (interactive input and
  output).


Python 3.10.6 final
===================

*Release date: 2022-08-01*


Security
--------

* gh-87389: "http.server": Fix an open redirection vulnerability in
  the HTTP server when an URI path starts with "//".  Vulnerability
  discovered, and initial fix proposed, by Hamza Avvan.

* gh-92888: Fix "memoryview" use after free when accessing the backing
  buffer in certain cases.


Core and Builtins
-----------------

* gh-95355: "_PyPegen_Parser_New" now properly detects token memory
  allocation errors. Patch by Honglin Zhu.

* gh-94938: Fix error detection in some builtin functions when keyword
  argument name is an instance of a str subclass with overloaded
  "__eq__" and "__hash__". Previously it could cause SystemError or
  other undesired behavior.

* gh-94949: "ast.parse()" will no longer parse parenthesized context
  managers when passed "feature_version" less than "(3, 9)". Patch by
  Shantanu Jain.

* gh-94947: "ast.parse()" will no longer parse assignment expressions
  when passed "feature_version" less than "(3, 8)". Patch by Shantanu
  Jain.

* gh-94869: Fix the column offsets for some expressions in multi-line
  f-strings "ast" nodes. Patch by Pablo Galindo.

* gh-91153: Fix an issue where a "bytearray" item assignment could
  crash if it’s resized by the new value’s "__index__()" method.

* gh-94329: Compile and run code with unpacking of extremely large
  sequences (1000s of elements). Such code failed to compile. It now
  compiles and runs correctly.

* gh-94360: Fixed a tokenizer crash when reading encoded files with
  syntax errors from "stdin" with non utf-8 encoded text. Patch by
  Pablo Galindo

* gh-94192: Fix error for dictionary literals with invalid expression
  as value.

* gh-93964: Strengthened compiler overflow checks to prevent crashes
  when compiling very large source files.

* gh-93671: Fix some exponential backtrace case happening with deeply
  nested sequence patterns in match statements. Patch by Pablo Galindo

* gh-93021: Fix the "__text_signature__" for "__get__()" methods
  implemented in C. Patch by Jelle Zijlstra.

* gh-92930: Fixed a crash in "_pickle.c" from mutating collections
  during "__reduce__" or "persistent_id".

* gh-92914: Always round the allocated size for lists up to the
  nearest even number.

* gh-92858: Improve error message for some suites with syntax error
  before ‘:’


Library
-------

* gh-95339: Update bundled pip to 22.2.1.

* gh-95045: Fix GC crash when deallocating "_lsprof.Profiler" by
  untracking it before calling any callbacks. Patch by Kumar Aditya.

* gh-95087: Fix IndexError in parsing invalid date in the "email"
  module.

* gh-95199: Upgrade bundled setuptools to 63.2.0.

* gh-95194: Upgrade bundled pip to 22.2.

* gh-93899: Fix check for existence of "os.EFD_CLOEXEC",
  "os.EFD_NONBLOCK" and "os.EFD_SEMAPHORE" flags on older kernel
  versions where these flags are not present. Patch by Kumar Aditya.

* gh-95166: Fix "concurrent.futures.Executor.map()" to cancel the
  currently waiting on future on an error - e.g. TimeoutError or
  KeyboardInterrupt.

* gh-93157: Fix "fileinput" module didn’t support "errors" option when
  "inplace" is true.

* gh-94821: Fix binding of unix socket to empty address on Linux to
  use an available address from the abstract namespace, instead of
  “0”.

* gh-94736: Fix crash when deallocating an instance of a subclass of
  "_multiprocessing.SemLock". Patch by Kumar Aditya.

* gh-94637: "SSLContext.set_default_verify_paths()" now releases the
  GIL around "SSL_CTX_set_default_verify_paths" call. The function
  call performs I/O and CPU intensive work.

* gh-94510: Re-entrant calls to "sys.setprofile()" and
  "sys.settrace()" now raise "RuntimeError". Patch by Pablo Galindo.

* gh-92336: Fix bug where "linecache.getline()" fails on bad files
  with "UnicodeDecodeError" or "SyntaxError". It now returns an empty
  string as per the documentation.

* gh-89988: Fix memory leak in "pickle.Pickler" when looking up
  "dispatch_table". Patch by Kumar Aditya.

* gh-94254: Fixed types of "struct" module to be immutable. Patch by
  Kumar Aditya.

* gh-94245: Fix pickling and copying of "typing.Tuple[()]".

* gh-94207: Made "_struct.Struct" GC-tracked in order to fix a
  reference leak in the "_struct" module.

* gh-94101: Manual instantiation of "ssl.SSLSession" objects is no
  longer allowed as it lead to misconfigured instances that crashed
  the interpreter when attributes where accessed on them.

* gh-84753: "inspect.iscoroutinefunction()",
  "inspect.isgeneratorfunction()", and "inspect.isasyncgenfunction()"
  now properly return "True" for duck-typed function-like objects like
  instances of "unittest.mock.AsyncMock".

  This makes "inspect.iscoroutinefunction()" consistent with the
  behavior of "asyncio.iscoroutinefunction()".  Patch by Mehdi
  ABAAKOUK.

* gh-83499: Fix double closing of file description in "tempfile".

* gh-79512: Fixed names and "__module__" value of "weakref" classes
  "ReferenceType", "ProxyType", "CallableProxyType". It makes them
  pickleable.

* gh-90494: "copy.copy()" and "copy.deepcopy()" now always raise a
  TypeError if "__reduce__()" returns a tuple with length 6 instead of
  silently ignore the 6th item or produce incorrect result.

* gh-90549: Fix a multiprocessing bug where a global named resource
  (such as a semaphore) could leak when a child process is spawned (as
  opposed to forked).

* gh-79579: "sqlite3" now correctly detects DML queries with leading
  comments. Patch by Erlend E. Aasland.

* gh-93421: Update "sqlite3.Cursor.rowcount" when a DML statement has
  run to completion. This fixes the row count for SQL queries like
  "UPDATE ... RETURNING". Patch by Erlend E. Aasland.

* gh-91810: Suppress writing an XML declaration in open files in
  "ElementTree.write()" with "encoding='unicode'" and
  "xml_declaration=None".

* gh-93353: Fix the "importlib.resources.as_file()" context manager to
  remove the temporary file if destroyed late during Python
  finalization: keep a local reference to the "os.remove()" function.
  Patch by Victor Stinner.

* gh-83658: Make "multiprocessing.Pool" raise an exception if
  "maxtasksperchild" is not "None" or a positive int.

* gh-74696: "shutil.make_archive()" no longer temporarily changes the
  current working directory during creation of standard ".zip" or tar
  archives.

* gh-91577: Move imports in "SharedMemory" methods to module level so
  that they can be executed late in python finalization.

* bpo-47231: Fixed an issue with inconsistent trailing slashes in
  tarfile longname directories.

* bpo-46755: In "QueueHandler", clear "stack_info" from "LogRecord" to
  prevent stack trace from being written twice.

* bpo-46053: Fix OSS audio support on NetBSD.

* bpo-46197: Fix "ensurepip" environment isolation for subprocess
  running "pip".

* bpo-45924: Fix "asyncio" incorrect traceback when future’s exception
  is raised multiple times. Patch by Kumar Aditya.

* bpo-34828: "sqlite3.Connection.iterdump()" now handles databases
  that use "AUTOINCREMENT" in one or more tables.


Documentation
-------------

* gh-94321: Document the **PEP 246** style protocol type
  "sqlite3.PrepareProtocol".

* gh-86128: Document a limitation in ThreadPoolExecutor where its exit
  handler is executed before any handlers in atexit.

* gh-61162: Clarify "sqlite3" behavior when How to use the connection
  context manager.

* gh-87260: Align "sqlite3" argument specs with the actual
  implementation.

* gh-86986: The minimum Sphinx version required to build the
  documentation is now 3.2.

* gh-88831: Augmented documentation of asyncio.create_task().
  Clarified the need to keep strong references to tasks and added a
  code snippet detailing how to do this.

* bpo-47161: Document that "pathlib.PurePath" does not collapse
  initial double slashes because they denote UNC paths.


Tests
-----

* gh-95280: Fix problem with "test_ssl" "test_get_ciphers" on systems
  that require perfect forward secrecy (PFS) ciphers.

* gh-95212: Make multiprocessing test case
  "test_shared_memory_recreate" parallel-safe.

* gh-91330: Added more tests for "dataclasses" to cover behavior with
  data descriptor-based fields.

* gh-94208: "test_ssl" is now checking for supported TLS version and
  protocols in more tests.

* gh-93951: In test_bdb.StateTestCase.test_skip, avoid including
  auxiliary importers.

* gh-93957: Provide nicer error reporting from subprocesses in
  test_venv.EnsurePipTest.test_with_pip.

* gh-57539: Increase calendar test coverage for
  "calendar.LocaleTextCalendar.formatweekday()".

* gh-92886: Fixing tests that fail when running with optimizations
  ("-O") in "test_zipimport.py"

* bpo-47016: Create a GitHub Actions workflow for verifying bundled
  pip and setuptools. Patch by Illia Volochii and Adam Turner.


Build
-----

* gh-94841: Fix the possible performance regression of
  "PyObject_Free()" compiled with MSVC version 1932.

* bpo-45816: Python now supports building with Visual Studio 2022
  (MSVC v143, VS Version 17.0). Patch by Jeremiah Vivian.


Windows
-------

* gh-90844: Allow virtual environments to correctly launch when they
  have spaces in the path.

* gh-92841: "asyncio" no longer throws "RuntimeError: Event loop is
  closed" on interpreter exit after asynchronous socket activity.
  Patch by Oleg Iarygin.

* bpo-42658: Support native Windows case-insensitive path comparisons
  by using "LCMapStringEx" instead of "str.lower()" in
  "ntpath.normcase()". Add "LCMapStringEx" to the "_winapi" module.


IDLE
----

* gh-95511: Fix the Shell context menu copy-with-prompts bug of
  copying an extra line when one selects whole lines.

* gh-95471: In the Edit menu, move "Select All" and add a new
  separator.

* gh-95411: Enable using IDLE’s module browser with .pyw files.

* gh-89610: Add .pyi as a recognized extension for IDLE on macOS.
  This allows opening stub files by double clicking on them in the
  Finder.


Tools/Demos
-----------

* gh-94538: Fix Argument Clinic output to custom file destinations.
  Patch by Erlend E. Aasland.

* gh-94430: Allow parameters named "module" and "self" with custom C
  names in Argument Clinic. Patch by Erlend E. Aasland


C API
-----

* gh-94930: Fix "SystemError" raised when
  "PyArg_ParseTupleAndKeywords()" is used with "#" in "(...)" but
  without "PY_SSIZE_T_CLEAN" defined.

* gh-94864: Fix "PyArg_Parse*" with deprecated format units “u” and
  “Z”. It returned 1 (success) when warnings are turned into
  exceptions.


Python 3.10.5 final
===================

*Release date: 2022-06-06*


Core and Builtins
-----------------

* gh-93418: Fixed an assert where an f-string has an equal sign ‘=’
  following an expression, but there’s no trailing brace. For example,
  f”{i=”.

* gh-91924: Fix "__ltrace__" debug feature if the stdout encoding is
  not UTF-8. Patch by Victor Stinner.

* gh-93061: Backward jumps after "async for" loops are no longer given
  dubious line numbers.

* gh-93065: Fix contextvars HAMT implementation to handle iteration
  over deep trees.

  The bug was discovered and fixed by Eli Libman. See
  MagicStack/immutables#84 for more details.

* gh-92311: Fixed a bug where setting "frame.f_lineno" to jump over a
  list comprehension could misbehave or crash.

* gh-92112: Fix crash triggered by an evil custom "mro()" on a
  metaclass.

* gh-92036: Fix a crash in subinterpreters related to the garbage
  collector. When a subinterpreter is deleted, untrack all objects
  tracked by its GC. To prevent a crash in deallocator functions
  expecting objects to be tracked by the GC, leak a strong reference
  to these objects on purpose, so they are never deleted and their
  deallocator functions are not called. Patch by Victor Stinner.

* gh-91421: Fix a potential integer overflow in _Py_DecodeUTF8Ex.

* bpo-47212: Raise "IndentationError" instead of "SyntaxError" for a
  bare "except" with no following indent. Improve "SyntaxError"
  locations for an un-parenthesized generator used as arguments. Patch
  by Matthieu Dartiailh.

* bpo-47182: Fix a crash when using a named unicode character like
  ""\N{digit nine}"" after the main interpreter has been initialized a
  second time.

* bpo-46775: Some Windows system error codes(>= 10000) are now mapped
  into the correct errno and may now raise a subclass of "OSError".
  Patch by Dong-hee Na.

* bpo-47117: Fix a crash if we fail to decode characters in
  interactive mode if the tokenizer buffers are uninitialized. Patch
  by Pablo Galindo.

* bpo-39829: Removed the "__len__()" call when initializing a list and
  moved initializing to "list_extend". Patch by Jeremiah Pascual.

* bpo-46962: Classes and functions that unconditionally declared their
  docstrings ignoring the "--without-doc-strings" compilation flag no
  longer do so.

  The classes affected are "ctypes.UnionType", "pickle.PickleBuffer",
  "testcapi.RecursingInfinitelyError", and "types.GenericAlias".

  The functions affected are 24 methods in "ctypes".

  Patch by Oleg Iarygin.

* bpo-36819: Fix crashes in built-in encoders with error handlers that
  return position less or equal than the starting position of non-
  encodable characters.


Library
-------

* gh-93156: Accessing the "pathlib.PurePath.parents" sequence of an
  absolute path using negative index values produced incorrect
  results.

* gh-89973: Fix "re.error" raised in "fnmatch" if the pattern contains
  a character range with upper bound lower than lower bound (e.g.
  "[c-a]"). Now such ranges are interpreted as empty ranges.

* gh-93010: In a very special case, the email package tried to append
  the nonexistent "InvalidHeaderError" to the defect list. It should
  have been "InvalidHeaderDefect".

* gh-92839: Fixed crash resulting from calling bisect.insort() or
  bisect.insort_left() with the key argument not equal to None.

* gh-91581: "utcfromtimestamp()" no longer attempts to resolve "fold"
  in the pure Python implementation, since the fold is never 1 in UTC.
  In addition to being slightly faster in the common case, this also
  prevents some errors when the timestamp is close to "datetime.min".
  Patch by Paul Ganssle.

* gh-92530: Fix an issue that occurred after interrupting
  "threading.Condition.notify()".

* gh-92049: Forbid pickling constants "re._constants.SUCCESS" etc.
  Previously, pickling did not fail, but the result could not be
  unpickled.

* bpo-47029: Always close the read end of the pipe used by
  "multiprocessing.Queue" *after* the last write of buffered data to
  the write end of the pipe to avoid "BrokenPipeError" at garbage
  collection and at "multiprocessing.Queue.close()" calls. Patch by
  Géry Ogam.

* gh-91401: Provide a fail-safe way to disable "subprocess" use of
  "vfork()" via a private "subprocess._USE_VFORK" attribute. While
  there is currently no known need for this, if you find a need please
  only set it to "False". File a CPython issue as to why you needed it
  and link to that from a comment in your code. This attribute is
  documented as a footnote in 3.11.

* gh-91910: Add missing f prefix to f-strings in error messages from
  the "multiprocessing" and "asyncio" modules.

* gh-91810: "ElementTree" method "write()" and function "tostring()"
  now use the text file’s encoding (“UTF-8” if not available) instead
  of locale encoding in XML declaration when "encoding="unicode"" is
  specified.

* gh-91832: Add "required" attribute to "argparse.Action" repr output.

* gh-91734: Fix OSS audio support on Solaris.

* gh-91700: Compilation of regular expression containing a conditional
  expression "(?(group)...)" now raises an appropriate "re.error" if
  the group number refers to not defined group. Previously an internal
  RuntimeError was raised.

* gh-91676: Fix "unittest.IsolatedAsyncioTestCase" to shutdown the per
  test event loop executor before returning from its "run" method so
  that a not yet stopped or garbage collected executor state does not
  persist beyond the test.

* gh-90568: Parsing "\N" escapes of Unicode Named Character Sequences
  in a "regular expression" raises now "re.error" instead of
  "TypeError".

* gh-91595: Fix the comparison of character and integer inside
  "Tools.gdb.libpython.write_repr()". Patch by Yu Liu.

* gh-90622: Worker processes for
  "concurrent.futures.ProcessPoolExecutor" are no longer spawned on
  demand (a feature added in 3.9) when the multiprocessing context
  start method is ""fork"" as that can lead to deadlocks in the child
  processes due to a fork happening while threads are running.

* gh-91575: Update case-insensitive matching in the "re" module to the
  latest Unicode version.

* gh-91581: Remove an unhandled error case in the C implementation of
  calls to "datetime.fromtimestamp" with no time zone (i.e. getting a
  local time from an epoch timestamp). This should have no user-facing
  effect other than giving a possibly more accurate error message when
  called with timestamps that fall on 10000-01-01 in the local time.
  Patch by Paul Ganssle.

* bpo-47260: Fix "os.closerange()" potentially being a no-op in a
  Linux seccomp sandbox.

* bpo-39064: "zipfile.ZipFile" now raises "zipfile.BadZipFile" instead
  of "ValueError" when reading a corrupt zip file in which the central
  directory offset is negative.

* bpo-47151: When subprocess tries to use vfork, it now falls back to
  fork if vfork returns an error. This allows use in situations where
  vfork isn’t allowed by the OS kernel.

* bpo-27929: Fix "asyncio.loop.sock_connect()" to only resolve names
  for "socket.AF_INET" or "socket.AF_INET6" families. Resolution may
  not make sense for other families, like "socket.AF_BLUETOOTH" and
  "socket.AF_UNIX".

* bpo-43323: Fix errors in the "email" module if the charset itself
  contains undecodable/unencodable characters.

* bpo-47101: "hashlib.algorithms_available" now lists only algorithms
  that are provided by activated crypto providers on OpenSSL 3.0.
  Legacy algorithms are not listed unless the legacy provider has been
  loaded into the default OSSL context.

* bpo-46787: Fix "concurrent.futures.ProcessPoolExecutor" exception
  memory leak

* bpo-45393: Fix the formatting for "await x" and "not x" in the
  operator precedence table when using the "help()" system.

* bpo-46415: Fix ipaddress.ip_{address,interface,network} raising
  TypeError instead of ValueError if given invalid tuple as address
  parameter.

* bpo-28249: Set "doctest.DocTest.lineno" to "None" when object does
  not have "__doc__".

* bpo-45138: Fix a regression in the "sqlite3" trace callback where
  bound parameters were not expanded in the passed statement string.
  The regression was introduced in Python 3.10 by bpo-40318. Patch by
  Erlend E. Aasland.

* bpo-44493: Add missing terminated NUL in sockaddr_un’s length

  This was potentially observable when using non-abstract AF_UNIX
  datagram sockets to processes written in another programming
  language.

* bpo-42627: Fix incorrect parsing of Windows registry proxy settings

* bpo-36073: Raise "ProgrammingError" instead of segfaulting on
  recursive usage of cursors in "sqlite3" converters. Patch by Sergey
  Fedoseev.


Documentation
-------------

* gh-86438: Clarify that "-W" and "PYTHONWARNINGS" are matched
  literally and case-insensitively, rather than as regular
  expressions, in "warnings".

* gh-92240: Added release dates for “What’s New in Python 3.X” for
  3.0, 3.1, 3.2, 3.8 and 3.10

* gh-91888: Add a new "gh" role to the documentation to link to GitHub
  issues.

* gh-91783: Document security issues concerning the use of the
  function "shutil.unpack_archive()"

* gh-91547: Remove “Undocumented modules” page.

* bpo-44347: Clarify the meaning of *dirs_exist_ok*, a kwarg of
  "shutil.copytree()".

* bpo-38668: Update the introduction to documentation for "os.path" to
  remove warnings that became irrelevant after the implementations of
  **PEP 383** and **PEP 529**.

* bpo-47138: Pin Jinja to a version compatible with Sphinx version
  3.2.1.

* bpo-46962: All docstrings in code snippets are now wrapped into
  "PyDoc_STR()" to follow the guideline of PEP 7’s Documentation
  Strings paragraph. Patch by Oleg Iarygin.

* bpo-26792: Improve the docstrings of "runpy.run_module()" and
  "runpy.run_path()". Original patch by Andrew Brezovsky.

* bpo-40838: Document that "inspect.getdoc()", "inspect.getmodule()",
  and "inspect.getsourcefile()" might return "None".

* bpo-45790: Adjust inaccurate phrasing in Defining Extension Types:
  Tutorial about the "ob_base" field and the macros used to access its
  contents.

* bpo-42340: Document that in some circumstances "KeyboardInterrupt"
  may cause the code to enter an inconsistent state. Provided a sample
  workaround to avoid it if needed.

* bpo-41233: Link the errnos referenced in
  "Doc/library/exceptions.rst" to their respective section in
  "Doc/library/errno.rst", and vice versa. Previously this was only
  done for EINTR and InterruptedError. Patch by Yan “yyyyyyyan”
  Orestes.

* bpo-38056: Overhaul the Error Handlers documentation in "codecs".

* bpo-13553: Document tkinter.Tk args.


Tests
-----

* gh-92886: Fixing tests that fail when running with optimizations
  ("-O") in "test_imaplib.py".

* gh-92670: Skip "test_shutil.TestCopy.test_copyfile_nonexistent_dir"
  test on AIX as the test uses a trailing slash to force the OS
  consider the path as a directory, but on AIX the trailing slash has
  no effect and is considered as a file.

* gh-91904: Fix initialization of "PYTHONREGRTEST_UNICODE_GUARD" which
  prevented running regression tests on non-UTF-8 locale.

* gh-91607: Fix "test_concurrent_futures" to test the correct
  multiprocessing start method context in several cases where the test
  logic mixed this up.

* bpo-47205: Skip test for "sched_getaffinity()" and
  "sched_setaffinity()" error case on FreeBSD.

* bpo-47104: Rewrite "asyncio.to_thread()" tests to use
  "unittest.IsolatedAsyncioTestCase".

* bpo-29890: Add tests for "ipaddress.IPv4Interface" and
  "ipaddress.IPv6Interface" construction with tuple arguments.
  Original patch and tests by louisom.


Build
-----

* bpo-47103: Windows "PGInstrument" builds now copy a required DLL
  into the output directory, making it easier to run the profile stage
  of a PGO build.


Windows
-------

* gh-92984: Explicitly disable incremental linking for non-Debug
  builds

* bpo-47194: Update "zlib" to v1.2.12 to resolve CVE-2018-25032.

* bpo-46785: Fix race condition between "os.stat()" and unlinking a
  file on Windows, by using errors codes returned by
  "FindFirstFileW()" when appropriate in "win32_xstat_impl".

* bpo-40859: Update Windows build to use xz-5.2.5


Tools/Demos
-----------

* gh-91583: Fix regression in the code generated by Argument Clinic
  for functions with the "defining_class" parameter.


Python 3.10.4 final
===================

*Release date: 2022-03-23*


Core and Builtins
-----------------

* bpo-46968: Check for the existence of the “sys/auxv.h” header in
  "faulthandler" to avoid compilation problems in systems where this
  header doesn’t exist. Patch by Pablo Galindo


Library
-------

* bpo-23691: Protect the "re.finditer()" iterator from re-entering.

* bpo-42369: Fix thread safety of "zipfile._SharedFile.tell()" to
  avoid a “zipfile.BadZipFile: Bad CRC-32 for file” exception when
  reading a "ZipFile" from multiple threads.

* bpo-38256: Fix "binascii.crc32()" when it is compiled to use zlib’c
  crc32 to work properly on inputs 4+GiB in length instead of
  returning the wrong result. The workaround prior to this was to
  always feed the function data in increments smaller than 4GiB or to
  just call the zlib module function.

* bpo-39394: A warning about inline flags not at the start of the
  regular expression now contains the position of the flag.

* bpo-47061: Deprecate the various modules listed by **PEP 594**:

  aifc, asynchat, asyncore, audioop, cgi, cgitb, chunk, crypt, imghdr,
  msilib, nntplib, nis, ossaudiodev, pipes, smtpd, sndhdr, spwd,
  sunau, telnetlib, uu, xdrlib

* bpo-2604: Fix bug where doctests using globals would fail when run
  multiple times.

* bpo-45997: Fix "asyncio.Semaphore" re-aquiring FIFO order.

* bpo-47022: The "asynchat", "asyncore" and  "smtpd" modules have been
  deprecated since at least Python 3.6. Their documentation and
  deprecation warnings and have now been updated to note they will
  removed in Python 3.12 (**PEP 594**).

* bpo-46421: Fix a unittest issue where if the command was invoked as
  "python -m unittest" and the filename(s) began with a dot (.), a
  "ValueError" is returned.

* bpo-40296: Fix supporting generic aliases in "pydoc".


Python 3.10.3 final
===================

*Release date: 2022-03-16*


Core and Builtins
-----------------

* bpo-46940: Avoid overriding "AttributeError" metadata information
  for nested attribute access calls. Patch by Pablo Galindo.

* bpo-46852: Rename the private undocumented "float.__set_format__()"
  method to "float.__setformat__()" to fix a typo introduced in Python
  3.7. The method is only used by test_float. Patch by Victor Stinner.

* bpo-46794: Bump up the libexpat version into 2.4.6

* bpo-46820: Fix parsing a numeric literal immediately (without
  spaces) followed by “not in” keywords, like in "1not in x". Now the
  parser only emits a warning, not a syntax error.

* bpo-46762: Fix an assert failure in debug builds when a ‘<’, ‘>’, or
  ‘=’ is the last character in an f-string that’s missing a closing
  right brace.

* bpo-46724: Make sure that all backwards jumps use the
  "JUMP_ABSOLUTE" instruction, rather than "JUMP_FORWARD" with an
  argument of "(2**32)+offset".

* bpo-46732: Correct the docstring for the "__bool__()" method. Patch
  by Jelle Zijlstra.

* bpo-46707: Avoid potential exponential backtracking when producing
  some syntax errors involving lots of brackets. Patch by Pablo
  Galindo.

* bpo-40479: Add a missing call to "va_end()" in
  "Modules/_hashopenssl.c".

* bpo-46615: When iterating over sets internally in "setobject.c",
  acquire strong references to the resulting items from the set.  This
  prevents crashes in corner-cases of various set operations where the
  set gets mutated.

* bpo-45773: Remove two invalid “peephole” optimizations from the
  bytecode compiler.

* bpo-43721: Fix docstrings of "getter", "setter", and "deleter" to
  clarify that they create a new copy of the property.

* bpo-46503: Fix an assert when parsing some invalid N escape
  sequences in f-strings.

* bpo-46417: Fix a race condition on setting a type "__bases__"
  attribute: the internal function "add_subclass()" now gets the
  "PyTypeObject.tp_subclasses" member after calling
  "PyWeakref_NewRef()" which can trigger a garbage collection which
  can indirectly modify "PyTypeObject.tp_subclasses". Patch by Victor
  Stinner.

* bpo-46383: Fix invalid signature of "_zoneinfo"’s "module_free"
  function to resolve a crash on wasm32-emscripten platform.

* bpo-46070: "Py_EndInterpreter()" now explicitly untracks all objects
  currently tracked by the GC. Previously, if an object was used later
  by another interpreter, calling "PyObject_GC_UnTrack()" on the
  object crashed if the previous or the next object of the "PyGC_Head"
  structure became a dangling pointer. Patch by Victor Stinner.

* bpo-46339: Fix a crash in the parser when retrieving the error text
  for multi-line f-strings expressions that do not start in the first
  line of the string. Patch by Pablo Galindo

* bpo-46240: Correct the error message for unclosed parentheses when
  the tokenizer doesn’t reach the end of the source when the error is
  reported. Patch by Pablo Galindo

* bpo-46091: Correctly calculate indentation levels for lines with
  whitespace character that are ended by line continuation characters.
  Patch by Pablo Galindo


Library
-------

* bpo-43253: Fix a crash when closing transports where the underlying
  socket handle is already invalid on the Proactor event loop.

* bpo-47004: Apply bugfixes from importlib_metadata 4.11.3, including
  bugfix for EntryPoint.extras, which was returning match objects and
  not the extras strings.

* bpo-46985: Upgrade pip wheel bundled with ensurepip (pip 22.0.4)

* bpo-46968: "faulthandler": On Linux 5.14 and newer, dynamically
  determine size of signal handler stack size CPython allocates using
  "getauxval(AT_MINSIGSTKSZ)". This changes allows for Python
  extension’s request to Linux kernel to use AMX_TILE instruction set
  on Sapphire Rapids Xeon processor to succeed, unblocking use of the
  ISA in frameworks.

* bpo-46955: Expose "asyncio.base_events.Server" as "asyncio.Server".
  Patch by Stefan Zabka.

* bpo-23325: The "signal" module no longer assumes that "SIG_IGN" and
  "SIG_DFL" are small int singletons.

* bpo-46932: Update bundled libexpat to 2.4.7

* bpo-25707: Fixed a file leak in "xml.etree.ElementTree.iterparse()"
  when the iterator is not exhausted. Patch by Jacob Walls.

* bpo-44886: Inherit asyncio proactor datagram transport from
  "asyncio.DatagramTransport".

* bpo-46827: Support UDP sockets in  "asyncio.loop.sock_connect()" for
  selector-based event loops.  Patch by Thomas Grainger.

* bpo-46811: Make test suite support Expat >=2.4.5

* bpo-46252: Raise "TypeError" if "ssl.SSLSocket" is passed to
  transport-based APIs.

* bpo-46784: Fix libexpat symbols collisions with user dynamically
  loaded or statically linked libexpat in embedded Python.

* bpo-39327: "shutil.rmtree()" can now work with VirtualBox shared
  folders when running from the guest operating-system.

* bpo-46756: Fix a bug in
  "urllib.request.HTTPPasswordMgr.find_user_password()" and
  "urllib.request.HTTPPasswordMgrWithPriorAuth.is_authenticated()"
  which allowed to bypass authorization. For example, access to URI
  "example.org/foobar" was allowed if the user was authorized for URI
  "example.org/foo".

* bpo-46643: In "typing.get_type_hints()", support evaluating
  stringified "ParamSpecArgs" and "ParamSpecKwargs" annotations. Patch
  by Gregory Beauregard.

* bpo-45863: When the "tarfile" module creates a pax format archive,
  it will put an integer representation of timestamps in the ustar
  header (if possible) for the benefit of older unarchivers, in
  addition to the existing full-precision timestamps in the pax
  extended header.

* bpo-46676: Make "typing.ParamSpec" args and kwargs equal to
  themselves. Patch by Gregory Beauregard.

* bpo-46672: Fix "NameError" in "asyncio.gather()" when initial type
  check fails.

* bpo-46655: In "typing.get_type_hints()", support evaluating bare
  stringified "TypeAlias" annotations. Patch by Gregory Beauregard.

* bpo-45948: Fixed a discrepancy in the C implementation of the
  "xml.etree.ElementTree" module. Now, instantiating an
  "xml.etree.ElementTree.XMLParser" with a "target=None" keyword
  provides a default "xml.etree.ElementTree.TreeBuilder" target as the
  Python implementation does.

* bpo-46521: Fix a bug in the "codeop" module that was incorrectly
  identifying invalid code involving string quotes as valid code.

* bpo-46581: Brings "ParamSpec" propagation for "GenericAlias" in line
  with "Concatenate" (and others).

* bpo-46591: Make the IDLE doc URL on the About IDLE dialog clickable.

* bpo-46400: expat: Update libexpat from 2.4.1 to 2.4.4

* bpo-46487: Add the "get_write_buffer_limits" method to
  "asyncio.transports.WriteTransport" and to the SSL transport.

* bpo-45173: Note the configparser deprecations will be removed in
  Python 3.12.

* bpo-46539: In "typing.get_type_hints()", support evaluating
  stringified "ClassVar" and "Final" annotations inside "Annotated".
  Patch by Gregory Beauregard.

* bpo-46491: Allow "typing.Annotated" to wrap "typing.Final" and
  "typing.ClassVar". Patch by Gregory Beauregard.

* bpo-46436: Fix command-line option "-d"/"--directory" in module
  "http.server" which is ignored when combined with command-line
  option "--cgi". Patch by Géry Ogam.

* bpo-41403: Make "mock.patch()" raise a "TypeError" with a relevant
  error message on invalid arg. Previously it allowed a cryptic
  "AttributeError" to escape.

* bpo-46474: In "importlib.metadata.EntryPoint.pattern", avoid
  potential REDoS by limiting ambiguity in consecutive whitespace.

* bpo-46469: "asyncio" generic classes now return "types.GenericAlias"
  in "__class_getitem__" instead of the same class.

* bpo-46434: "pdb" now gracefully handles "help" when "__doc__" is
  missing, for example when run with pregenerated optimized ".pyc"
  files.

* bpo-46333: The "__eq__()" and "__hash__()" methods of
  "typing.ForwardRef" now honor the "module" parameter of
  "typing.ForwardRef". Forward references from different modules are
  now differentiated.

* bpo-46246: Add missing "__slots__" to
  "importlib.metadata.DeprecatedList". Patch by Arie Bovenberg.

* bpo-46266: Improve day constants in "calendar".

  Now all constants ("MONDAY" … "SUNDAY") are documented, tested, and
  added to "__all__".

* bpo-46232: The "ssl" module now handles certificates with bit
  strings in DN correctly.

* bpo-43118: Fix a bug in "inspect.signature()" that was causing it to
  fail on some subclasses of classes with a "__text_signature__"
  referencing module globals. Patch by Weipeng Hong.

* bpo-26552: Fixed case where failing "asyncio.ensure_future()" did
  not close the coroutine. Patch by Kumar Aditya.

* bpo-21987: Fix an issue with "tarfile.TarFile.getmember()" getting a
  directory name with a trailing slash.

* bpo-20392: Fix inconsistency with uppercase file extensions in
  "MimeTypes.guess_type()". Patch by Kumar Aditya.

* bpo-46080: Fix exception in argparse help text generation if a
  "argparse.BooleanOptionalAction" argument’s default is
  "argparse.SUPPRESS" and it has "help" specified.  Patch by Felix
  Fontein.

* bpo-44439: Fix ".write()" method of a member file in "ZipFile", when
  the input data is an object that supports the buffer protocol, the
  file length may be wrong.

* bpo-45703: When a namespace package is imported before another
  module from the same namespace is created/installed in a different
  "sys.path" location while the program is running, calling the
  "importlib.invalidate_caches()" function will now also guarantee the
  new module is noticed.

* bpo-24959: Fix bug where "unittest" sometimes drops frames from
  tracebacks of exceptions raised in tests.

* bpo-44791: Fix substitution of "ParamSpec" in "Concatenate" with
  different parameter expressions. Substitution with a list of types
  returns now a tuple of types. Substitution with "Concatenate"
  returns now a "Concatenate" with concatenated lists of arguments.

* bpo-14156: argparse.FileType now supports an argument of ‘-’ in
  binary mode, returning the .buffer attribute of sys.stdin/sys.stdout
  as appropriate. Modes including ‘x’ and ‘a’ are treated equivalently
  to ‘w’ when argument is ‘-’. Patch contributed by Josh Rosenberg


Documentation
-------------

* bpo-46463: Fixes "escape4chm.py" script used when building the CHM
  documentation file


Tests
-----

* bpo-46913: Fix test_faulthandler.test_sigfpe() if Python is built
  with undefined behavior sanitizer (UBSAN): disable UBSAN on the
  faulthandler_sigfpe() function. Patch by Victor Stinner.

* bpo-46708: Prevent default asyncio event loop policy modification
  warning after "test_asyncio" execution.

* bpo-46678: The function "make_legacy_pyc" in
  "Lib/test/support/import_helper.py" no longer fails when
  "PYTHONPYCACHEPREFIX" is set to a directory on a different device
  from where tempfiles are stored.

* bpo-46616: Ensures "test_importlib.test_windows" cleans up registry
  keys after completion.

* bpo-44359: test_ftplib now silently ignores socket errors to prevent
  logging unhandled threading exceptions. Patch by Victor Stinner.

* bpo-46542: Fix a Python crash in test_lib2to3 when using Python
  built in debug mode: limit the recursion limit. Patch by Victor
  Stinner.

* bpo-46576: test_peg_generator now disables compiler optimization
  when testing compilation of its own C extensions to significantly
  speed up the testing on non-debug builds of CPython.

* bpo-46542: Fix "test_json" tests checking for "RecursionError":
  modify these tests to use "support.infinite_recursion()". Patch by
  Victor Stinner.

* bpo-13886: Skip test_builtin PTY tests on non-ASCII characters if
  the readline module is loaded. The readline module changes input()
  behavior, but test_builtin is not intented to test the readline
  module. Patch by Victor Stinner.


Build
-----

* bpo-47032: Ensure Windows install builds fail correctly with a non-
  zero exit code when part of the build fails.

* bpo-47024: Update OpenSSL to 1.1.1n for macOS installers and all
  Windows builds.

* bpo-38472: Fix GCC detection in setup.py when cross-compiling. The C
  compiler is now run with LC_ALL=C. Previously, the detection failed
  with a German locale.

* bpo-46513: **configure** no longer uses "AC_C_CHAR_UNSIGNED" macro
  and "pyconfig.h" no longer defines reserved symbol
  "__CHAR_UNSIGNED__".

* bpo-45925: Update Windows installer to use SQLite 3.37.2.


Windows
-------

* bpo-44549: Update bzip2 to 1.0.8 in Windows builds to mitigate
  CVE-2016-3189 and CVE-2019-12900

* bpo-46948: Prevent CVE-2022-26488 by ensuring the Add to PATH option
  in the Windows installer uses the correct path when being repaired.

* bpo-46638: Ensures registry virtualization is consistently disabled.
  For 3.10 and earlier, it remains enabled (some registry writes are
  protected), while for 3.11 and later it is disabled (registry
  modifications affect all applications).


macOS
-----

* bpo-45925: Update macOS installer to SQLite 3.37.2.


IDLE
----

* bpo-46630: Make query dialogs on Windows start with a cursor in the
  entry box.

* bpo-45296: Clarify close, quit, and exit in IDLE.  In the File menu,
  ‘Close’ and ‘Exit’ are now ‘Close Window’ (the current one) and
  ‘Exit’ is now ‘Exit IDLE’ (by closing all windows).  In Shell,
  ‘quit()’ and ‘exit()’ mean ‘close Shell’. If there are no other
  windows, this also exits IDLE.

* bpo-45447: Apply IDLE syntax highlighting to "pyi" files. Patch by
  Alex Waygood and Terry Jan Reedy.


C API
-----

* bpo-46433: The internal function _PyType_GetModuleByDef now
  correctly handles inheritance patterns involving static types.

* bpo-14916: Fixed bug in the tokenizer that prevented
  "PyRun_InteractiveOne" from parsing from the provided FD.


Python 3.10.2 final
===================

*Release date: 2022-01-13*


Core and Builtins
-----------------

* bpo-46347: Fix memory leak in PyEval_EvalCodeEx.

* bpo-46289: ASDL declaration of "FormattedValue" has changed to
  reflect "conversion" field is not optional.

* bpo-46237: Fix the line number of tokenizer errors inside f-strings.
  Patch by Pablo Galindo.

* bpo-46006: Fix a regression when a type method like "__init__()" is
  modified in a subinterpreter. Fix a regression in
  "_PyUnicode_EqualToASCIIId()" and type "update_slot()". Revert the
  change which made the Unicode dictionary of interned strings
  compatible with subinterpreters: the internal interned dictionary is
  shared again by all interpreters. Patch by Victor Stinner.

* bpo-46085: Fix iterator cache mechanism of "OrderedDict".

* bpo-46110: Add a maximum recursion check to the PEG parser to avoid
  stack overflow. Patch by Pablo Galindo

* bpo-46054: Fix parser error when parsing non-utf8 characters in
  source files. Patch by Pablo Galindo.

* bpo-46042: Improve the location of the caret in "SyntaxError"
  exceptions emitted by the symbol table. Patch by Pablo Galindo.

* bpo-46025: Fix a crash in the "atexit" module involving functions
  that unregister themselves before raising exceptions. Patch by Pablo
  Galindo.

* bpo-46009: Restore behavior from 3.9 and earlier when sending non-
  None to newly started generator. In 3.9 this did not affect the
  state of the generator. In 3.10.0 and 3.10.1 "gen_func().send(0)" is
  equivalent to "gen_func().throw(TypeError(...)" which exhausts the
  generator. In 3.10.2 onward, the behavior has been reverted to that
  of 3.9.

* bpo-46000: Improve compatibility of the "curses" module with NetBSD
  curses.

* bpo-46004: Fix the "SyntaxError" location for errors involving for
  loops with invalid targets. Patch by Pablo Galindo

* bpo-42918: Fix bug where the built-in "compile()" function did not
  always raise a "SyntaxError" when passed multiple statements in
  ‘single’ mode. Patch by Weipeng Hong.


Library
-------

* bpo-40479: Fix "hashlib" *usedforsecurity* option to work correctly
  with OpenSSL 3.0.0 in FIPS mode.

* bpo-46070: Fix possible segfault when importing the "asyncio" module
  from different sub-interpreters in parallel. Patch by Erlend E.
  Aasland.

* bpo-46278: Reflect "context" argument in
  "AbstractEventLoop.call_*()" methods. Loop implementations already
  support it.

* bpo-46239: Improve error message when importing
  "asyncio.windows_events" on non-Windows.

* bpo-20369: "concurrent.futures.wait()" no longer blocks forever when
  given duplicate Futures. Patch by Kumar Aditya.

* bpo-46105: Honor spec when generating requirement specs with urls
  and extras (importlib_metadata 4.8.3).

* bpo-26952: "argparse" raises "ValueError" with clear message when
  trying to render usage for an empty mutually-exclusive group.
  Previously it raised a cryptic "IndexError".

* bpo-27718: Fix help for the "signal" module. Some functions (e.g.
  "signal()" and "getsignal()") were omitted.

* bpo-46032: The "registry()" method of "functools.singledispatch()"
  functions checks now the first argument or the first parameter
  annotation and raises a TypeError if it is not supported. Previously
  unsupported “types” were ignored (e.g. "typing.List[int]") or caused
  an error at calling time (e.g. "list[int]").

* bpo-46018: Ensure that "math.expm1()" does not raise on underflow.

* bpo-45755: "typing" generic aliases now reveal the class attributes
  of the original generic class when passed to "dir()". This was the
  behavior up to Python 3.6, but was changed in 3.7-3.9.

* bpo-13236: "unittest.TextTestResult" and "unittest.TextTestRunner"
  flush now the output stream more often.

* bpo-42378: Fixes the issue with log file being overwritten when
  "logging.FileHandler" is used in "atexit" with *filemode* set to
  "'w'". Note this will cause the message in *atexit* not being logged
  if the log stream is already closed due to shutdown of logging.


Documentation
-------------

* bpo-46120: State that "|" is preferred for readability over "Union"
  in the "typing" docs.

* bpo-46040: Fix removal Python version for "@asyncio.coroutine", the
  correct value is 3.11.

* bpo-19737: Update the documentation for the "globals()" function.

* bpo-45840: Improve cross-references in the documentation for the
  data model.


Tests
-----

* bpo-46205: Fix hang in runtest_mp due to race condition

* bpo-46263: Fix test_capi on FreeBSD 14-dev: instruct jemalloc to not
  fill freed memory with junk byte.

* bpo-46150: Now "fakename" in
  "test_pathlib.PosixPathTest.test_expanduser" is checked to be non-
  existent.

* bpo-46129: Rewrite "asyncio.locks" tests with
  "unittest.IsolatedAsyncioTestCase" usage.

* bpo-46114: Fix test case for OpenSSL 3.0.1 version. OpenSSL 3.0 uses
  "0xMNN00PP0L".


Build
-----

* bpo-46263: "configure" no longer sets "MULTIARCH" on FreeBSD
  platforms.

* bpo-46106: Updated OpenSSL to 1.1.1m in Windows builds, macOS
  installer builds, and CI. Patch by Kumar Aditya.


macOS
-----

* bpo-40477: The Python Launcher app for macOS now properly launches
  scripts and, if necessary, the Terminal app when running on recent
  macOS releases.


C API
-----

* bpo-46236: Fix a bug in "PyFunction_GetAnnotations()" that caused it
  to return a "tuple" instead of a "dict".


Python 3.10.1 final
===================

*Release date: 2021-12-06*


Core and Builtins
-----------------

* bpo-42268: Fail the configure step if the selected compiler doesn’t
  support memory sanitizer. Patch by Pablo Galindo

* bpo-45727: Refine the custom syntax error that suggests that a comma
  may be missing to trigger only when the expressions are detected
  between parentheses or brackets. Patch by Pablo Galindo

* bpo-45614: Fix "traceback" display for exceptions with invalid
  module name.

* bpo-45848: Allow the parser to obtain error lines directly from
  encoded files. Patch by Pablo Galindo

* bpo-45826: Fixed a crash when calling ".with_traceback(None)" on
  "NameError". This occurs internally in
  "unittest.TestCase.assertRaises()".

* bpo-45822: Fixed a bug in the parser that was causing it to not
  respect **PEP 263** coding cookies when no flags are provided. Patch
  by Pablo Galindo

* bpo-45820: Fix a segfault when the parser fails without reading any
  input. Patch by Pablo Galindo

* bpo-42540: Fix crash when "os.fork()" is called with an active non-
  default memory allocator.

* bpo-45738: Fix computation of error location for invalid
  continuation characters in the parser. Patch by Pablo Galindo.

* bpo-45773: Fix a compiler hang when attempting to optimize certain
  jump patterns.

* bpo-45716: Improve the "SyntaxError" message when using "True",
  "None" or "False" as keywords in a function call. Patch by Pablo
  Galindo.

* bpo-45688: "sys.stdlib_module_names" now contains the macOS-specific
  module "_scproxy".

* bpo-30570: Fixed a crash in "issubclass()" from infinite recursion
  when searching pathological "__bases__" tuples.

* bpo-45521: Fix a bug in the obmalloc radix tree code.  On 64-bit
  machines, the bug causes the tree to hold 46-bits of virtual
  addresses, rather than the intended 48-bits.

* bpo-45494: Fix parser crash when reporting errors involving invalid
  continuation characters. Patch by Pablo Galindo.

* bpo-45408: Fix a crash in the parser when reporting tokenizer errors
  that occur at the same time unclosed parentheses are detected. Patch
  by Pablo Galindo.

* bpo-45385: Fix reference leak from descr_check. Patch by Dong-hee
  Na.

* bpo-45167: Fix deepcopying of "types.GenericAlias" objects.

* bpo-44219: Release the GIL while performing "isatty" system calls on
  arbitrary file descriptors. In particular, this affects
  "os.isatty()", "os.device_encoding()" and "io.TextIOWrapper". By
  extension, "io.open()" in text mode is also affected. This change
  solves a deadlock in "os.isatty()". Patch by Vincent Michel in
  bpo-44219.

* bpo-44959: Added fallback to extension modules with ‘.sl’ suffix on
  HP-UX

* bpo-44050: Extensions that indicate they use global state (by
  setting "m_size" to -1) can again be used in multiple interpreters.
  This reverts to behavior of Python 3.8.

* bpo-45121: Fix issue where "Protocol.__init__" raises
  "RecursionError" when it’s called directly or via "super()". Patch
  provided by Yurii Karabas.

* bpo-45083: When the interpreter renders an exception, its name now
  has a complete qualname. Previously only the class name was
  concatenated to the module name, which sometimes resulted in an
  incorrect full name being displayed.

  (This issue impacted only the C code exception rendering, the
  "traceback" module was using qualname already).

* bpo-45056: Compiler now removes trailing unused constants from
  co_consts.


Library
-------

* bpo-27946: Fix possible crash when getting an attribute of
  class:"xml.etree.ElementTree.Element" simultaneously with replacing
  the "attrib" dict.

* bpo-37658: Fix issue when on certain conditions "asyncio.wait_for()"
  may allow a coroutine to complete successfully, but fail to return
  the result, potentially causing memory leaks or other issues.

* bpo-44649: Handle dataclass(slots=True) with a field that has
  default a default value, but for which init=False.

* bpo-45803: Added missing kw_only parameter to
  dataclasses.make_dataclass().

* bpo-45831: "faulthandler" can now write ASCII-only strings (like
  filenames and function names) with a single write() syscall when
  dumping a traceback. It reduces the risk of getting an unreadable
  dump when two threads or two processes dump a traceback to the same
  file (like stderr) at the same time. Patch by Victor Stinner.

* bpo-41735: Fix thread lock in "zlib.Decompress.flush()" method
  before "PyObject_GetBuffer".

* bpo-45235: Reverted an argparse bugfix that caused regression in the
  handling of default arguments for subparsers.  This prevented leaf
  level arguments from taking precedence over root level arguments.

* bpo-45765: In importlib.metadata, fix distribution discovery for an
  empty path.

* bpo-45757: Fix bug where "dis" produced an incorrect oparg when
  "EXTENDED_ARG" is followed by an opcode that does not use its
  argument.

* bpo-45644: In-place JSON file formatting using "python3 -m json.tool
  infile infile" now works correctly, previously it left the file
  empty. Patch by Chris Wesseling.

* bpo-45679: Fix caching of multi-value "typing.Literal".
  "Literal[True, 2]" is no longer equal to "Literal[1, 2]".

* bpo-45664: Fix "types.resolve_bases()" and "types.new_class()" for
  "types.GenericAlias" instance as a base.

* bpo-45663: Fix "dataclasses.is_dataclass()" for dataclasses which
  are subclasses of "types.GenericAlias".

* bpo-45662: Fix the repr of "dataclasses.InitVar" with a type alias
  to the built-in class, e.g. "InitVar[list[int]]".

* bpo-45438: Fix typing.Signature string representation for generic
  builtin types.

* bpo-45574: Fix warning about "print_escape" being unused.

* bpo-45581: "sqlite3.connect()" now correctly raises "MemoryError" if
  the underlying SQLite API signals memory error. Patch by Erlend E.
  Aasland.

* bpo-45557: pprint.pprint() now handles underscore_numbers correctly.
  Previously it was always setting it to False.

* bpo-45515: Add references to "zoneinfo" in the "datetime"
  documentation, mostly replacing outdated references to
  "dateutil.tz". Change by Paul Ganssle.

* bpo-45475: Reverted optimization of iterating "gzip.GzipFile",
  "bz2.BZ2File", and "lzma.LZMAFile" (see bpo-43787) because it caused
  regression when user iterate them without having reference of them.
  Patch by Inada Naoki.

* bpo-45428: Fix a regression in py_compile when reading filenames
  from standard input.

* bpo-45467: Fix incremental decoder and stream reader in the “raw-
  unicode-escape” codec. Previously they failed if the escape sequence
  was split.

* bpo-45461: Fix incremental decoder and stream reader in the
  “unicode-escape” codec. Previously they failed if the escape
  sequence was split.

* bpo-45239: Fixed "email.utils.parsedate_tz()" crashing with
  "UnboundLocalError" on certain invalid input instead of returning
  "None". Patch by Ben Hoyt.

* bpo-45249: Fix the behaviour of "traceback.print_exc()" when
  displaying the caret when the "end_offset" in the exception is set
  to 0. Patch by Pablo Galindo

* bpo-45416: Fix use of "asyncio.Condition" with explicit
  "asyncio.Lock" objects, which was a regression due to removal of
  explicit loop arguments. Patch by Joongi Kim.

* bpo-45419: Correct interfaces on DegenerateFiles.Path.

* bpo-44904: Fix bug in the "doctest" module that caused it to fail if
  a docstring included an example with a "classmethod" "property".
  Patch by Alex Waygood.

* bpo-45406: Make "inspect.getmodule()" catch "FileNotFoundError"
  raised by :’func:"inspect.getabsfile", and return "None" to indicate
  that the module could not be determined.

* bpo-45262: Prevent use-after-free in asyncio. Make sure the cached
  running loop holder gets cleared on dealloc to prevent use-after-
  free in get_running_loop

* bpo-45386: Make "xmlrpc.client" more robust to C runtimes where the
  underlying C "strftime" function results in a "ValueError" when
  testing for year formatting options.

* bpo-45371: Fix clang rpath issue in "distutils". The UnixCCompiler
  now uses correct clang option to add a runtime library directory
  (rpath) to a shared library.

* bpo-20028: Improve error message of "csv.Dialect" when initializing.
  Patch by Vajrasky Kok and Dong-hee Na.

* bpo-45343: Update bundled pip to 21.2.4 and setuptools to 58.1.0

* bpo-45329: Fix freed memory access in "pyexpat.xmlparser" when
  building it with an installed expat library <= 2.2.0.

* bpo-41710: On Unix, if the "sem_clockwait()" function is available
  in the C library (glibc 2.30 and newer), the
  "threading.Lock.acquire()" method now uses the monotonic clock
  ("time.CLOCK_MONOTONIC") for the timeout, rather than using the
  system clock ("time.CLOCK_REALTIME"), to not be affected by system
  clock changes. Patch by Victor Stinner.

* bpo-45328: Fixed "http.client.HTTPConnection" to work properly in
  OSs that don’t support the "TCP_NODELAY" socket option.

* bpo-1596321: Fix the "threading._shutdown()" function when the
  "threading" module was imported first from a thread different than
  the main thread: no longer log an error at Python exit.

* bpo-45274: Fix a race condition in the "Thread.join()" method of the
  "threading" module. If the function is interrupted by a signal and
  the signal handler raises an exception, make sure that the thread
  remains in a consistent state to prevent a deadlock. Patch by Victor
  Stinner.

* bpo-45238: Fix "unittest.IsolatedAsyncioTestCase.debug()": it runs
  now asynchronous methods and callbacks.

* bpo-36674: "unittest.TestCase.debug()" raises now a
  "unittest.SkipTest" if the class or the test method are decorated
  with the skipping decorator.

* bpo-45235: Fix an issue where argparse would not preserve values in
  a provided namespace when using a subparser with defaults.

* bpo-45183: Have zipimport.zipimporter.find_spec() not raise an
  exception when the underlying zip file has been deleted and the
  internal cache has been reset via invalidate_cache().

* bpo-45234: Fixed a regression in "copyfile()", "copy()", "copy2()"
  raising "FileNotFoundError" when source is a directory, which should
  raise "IsADirectoryError"

* bpo-45228: Fix stack buffer overflow in parsing J1939 network
  address.

* bpo-45192: Fix the "tempfile._infer_return_type" function so that
  the "dir" argument of the "tempfile" functions accepts an object
  implementing the "os.PathLike" protocol.

  Patch by Kyungmin Lee.

* bpo-42135: Fix typo: "importlib.find_loader" is really slated for
  removal in Python 3.12 not 3.10, like the others in PR 25169.

  Patch by Hugo van Kemenade.

* bpo-45160: When tracing a tkinter variable used by a ttk OptionMenu,
  callbacks are no longer made twice.

* bpo-35474: Calling "mimetypes.guess_all_extensions()" with
  "strict=False" no longer affects the result of the following call
  with "strict=True". Also, mutating the returned list no longer
  affects the global state.

* bpo-45166: "typing.get_type_hints()" now works with "Final" wrapped
  in "ForwardRef".

* bpo-20499: Improve the speed and accuracy of statistics.pvariance().

* bpo-24444: Fixed an error raised in "argparse" help display when
  help for an option is set to 1+ blank spaces or when *choices* arg
  is an empty container.

* bpo-45021: Fix a potential deadlock at shutdown of forked children
  when using "concurrent.futures" module

* bpo-39039: tarfile.open raises "ReadError" when a zlib error occurs
  during file extraction.

* bpo-44594: Fix an edge case of "ExitStack" and "AsyncExitStack"
  exception chaining.  They will now match "with" block behavior when
  "__context__" is explicitly set to "None" when the exception is in
  flight.

* bpo-44295: Ensure deprecation warning from
  "assertDictContainsSubset()" points at calling code - by Anthony
  Sottile.

* bpo-43498: Avoid a possible *“RuntimeError: dictionary changed size
  during iteration”* when adjusting the process count of
  "ProcessPoolExecutor".


Documentation
-------------

* bpo-45640: Properly marked-up grammar tokens in the documentation
  are now clickable and take you to the definition of a given piece of
  grammar. Patch by Arthur Milchior.

* bpo-45788: Link doc for sys.prefix to sysconfig doc on installation
  paths.

* bpo-45772: "socket.socket" documentation is corrected to a class
  from a function.

* bpo-45392: Update the docstring of the "type" built-in to remove a
  redundant line and to mention keyword arguments for the constructor.

* bpo-45726: Improve documentation for "functools.singledispatch()"
  and "functools.singledispatchmethod".

* bpo-45680: Amend the docs on "GenericAlias" objects to clarify that
  non-container classes can also implement "__class_getitem__". Patch
  contributed by Alex Waygood.

* bpo-45655: Add a new “relevant PEPs” section to the top of the
  documentation for the "typing" module. Patch by Alex Waygood.

* bpo-45604: Add "level" argument to "multiprocessing.log_to_stderr"
  function docs.

* bpo-45250: Update the documentation to note that CPython does not
  consistently require iterators to define "__iter__".

* bpo-45464: Mention in the documentation of Built-in Exceptions that
  inheriting from multiple exception types in a single subclass is not
  recommended due to possible memory layout incompatibility.

* bpo-45449: Add note about **PEP 585** in "collections.abc".

* bpo-45516: Add protocol description to the
  "importlib.abc.Traversable" documentation.

* bpo-20692: Add Programming FAQ entry explaining that int literal
  attribute access requires either a space after or parentheses around
  the literal.

* bpo-45216: Remove extra documentation listing methods in "difflib".
  It was rendering twice in pydoc and was outdated in some places.

* bpo-45024: "collections.abc" documentation has been expanded to
  explicitly cover how instance and subclass checks work, with
  additional doctest examples and an exhaustive list of ABCs which
  test membership purely by presence of the right *special method*s.
  Patch by Raymond Hettinger.

* bpo-25381: In the extending chapter of the extending doc, update a
  paragraph about the global variables containing exception
  information.

* bpo-43905: Expanded "astuple()" and "asdict()" docs, warning about
  deepcopy being applied and providing a workaround.


Tests
-----

* bpo-19460: Add new Test for
  "email.mime.nonmultipart.MIMENonMultipart".

* bpo-45835: Fix race condition in test_queue tests with multiple
  “feeder” threads.

* bpo-45678: Add tests for scenarios in which
  "functools.singledispatchmethod" is stacked on top of a method that
  has already been wrapped by two other decorators. Patch by Alex
  Waygood.

* bpo-45578: Add tests for "dis.distb()"

* bpo-45678: Add tests to ensure that "functools.singledispatchmethod"
  correctly wraps the attributes of the target function.

* bpo-45577: Add subtests for all "pickle" protocols in
  "test_zoneinfo".

* bpo-45566: Fix "test_frozen_pickle" in "test_dataclasses" to check
  all "pickle" versions.

* bpo-43592: "test.libregrtest" now raises the soft resource limit for
  the maximum number of file descriptors when the default is too low
  for our test suite as was often the case on macOS.

* bpo-39679: Add more test cases for "@functools.singledispatchmethod"
  when combined with "@classmethod" or "@staticmethod".

* bpo-45400: Fix
  test_name_error_suggestions_do_not_trigger_for_too_many_locals() of
  test_exceptions if a directory name contains “a1” (like
  “Python-3.11.0a1”): use a stricter regular expression. Patch by
  Victor Stinner.

* bpo-40173: Fix "test.support.import_helper.import_fresh_module()".

* bpo-45280: Add a test case for empty "typing.NamedTuple".

* bpo-45269: Cover case when invalid "markers" type is supplied to
  "c_make_encoder".

* bpo-45128: Fix "test_multiprocessing_fork" failure due to
  "test_logging" and "sys.modules" manipulation.

* bpo-45209: Fix "UserWarning: resource_tracker" warning in "_test_mu
  ltiprocessing._TestSharedMemory.test_shared_memory_cleaned_after_pr
  ocess_termination"

* bpo-45195: Fix test_readline.test_nonascii(): sometimes, the newline
  character is not written at the end, so don’t expect it in the
  output. Patch by Victor Stinner.

* bpo-45156: Fixes infinite loop on "unittest.mock.seal()" of mocks
  created by "create_autospec()".

* bpo-45125: Improves pickling tests and docs of "SharedMemory" and
  "SharableList" objects.

* bpo-44860: Update "test_sysconfig.test_user_similar()" for the
  posix_user scheme: "platlib" doesn’t use "sys.platlibdir". Patch by
  Victor Stinner.

* bpo-25130: Add calls of "gc.collect()" in tests to support PyPy.


Build
-----

* bpo-44035: CI now verifies that autoconf files have been regenerated
  with a current and unpatched autoconf package.

* bpo-33393: Update "config.guess" to 2021-06-03 and "config.sub" to
  2021-08-14. "Makefile" now has an "update-config" target to make
  updating more convenient.

* bpo-45866: "make regen-all" now produces the same output when run
  from a directory other than the source tree: when building Python
  out of the source tree. pegen now strips directory of the “generated
  by pygen from <FILENAME>” header Patch by Victor Stinner.

* bpo-41498: Python now compiles on platforms without "sigset_t".
  Several functions in "signal" are not available when "sigset_t" is
  missing.

  Based on patch by Roman Yurchak for pyodide.

* bpo-45881: "setup.py" now uses "CC" from environment first to
  discover multiarch and cross compile paths.

* bpo-43158: "setup.py" now uses values from configure script to build
  the "_uuid" extension module. Configure now detects util-linux’s
  "libuuid", too.

* bpo-45571: "Modules/Setup" now use "PY_CFLAGS_NODIST" instead of
  "PY_CFLAGS" to compile shared modules.

* bpo-45561: Run smelly.py tool from $(srcdir).

* bpo-45532: Update "sys.version" to use "main" as fallback
  information. Patch by Jeong YunWon.

* bpo-45536: The "configure" script now checks whether OpenSSL headers
  and libraries provide required APIs. Most common APIs are verified.
  The check detects outdated or missing OpenSSL. Failures do not stop
  configure.

* bpo-45221: Fixed regression in handling of "LDFLAGS" and "CPPFLAGS"
  options where "argparse.parse_known_args()" could interpret an
  option as one of the built-in command line argument, for example
  "-h" for help.

* bpo-45405: Prevent "internal configure error" when running
  "configure" with recent versions of non-Apple clang.  Patch by David
  Bohman.

* bpo-45220: Avoid building with the Windows 11 SDK previews
  automatically. This may be overridden by setting the
  "DefaultWindowsSDKVersion" environment variable before building.

* bpo-45067: The ncurses function extended_color_content was
  introduced in 2017

  (https://invisible-island.net/ncurses/NEWS.html#index-t20170401).
  The

  ncurses-devel package in CentOS 7 had a older version ncurses
  resulted in compilation error.  For compiling ncurses with extended
  color support, we verify the version of the ncurses library >=
  20170401.


Windows
-------

* bpo-45901: When installed through the Microsoft Store and set as the
  default app for "*.py" files, command line arguments will now be
  passed to Python when invoking a script without explicitly launching
  Python (that is, "script.py args" rather than "python script.py
  args").

* bpo-45616: Fix Python Launcher’s ability to distinguish between
  versions 3.1 and 3.10 when either one is explicitly requested.
  Previously, 3.1 would be used if 3.10 was requested but not
  installed, and 3.10 would be used if 3.1 was requested but 3.10 was
  installed.

* bpo-45732: Updates bundled Tcl/Tk to 8.6.12.

* bpo-45720: Internal reference to "shlwapi.dll" was dropped to help
  improve startup time. This DLL will no longer be loaded at the start
  of every Python process.

* bpo-43652: Update Tcl/Tk to 8.6.11, actually this time. The previous
  update incorrectly included 8.6.10.

* bpo-45337: venv now warns when the created environment may need to
  be accessed at a different path, due to redirections, links or
  junctions. It also now correctly installs or upgrades components
  when the alternate path is required.


macOS
-----

* bpo-45732: Update python.org macOS installer to use Tcl/Tk 8.6.12.

* bpo-44828: Avoid tkinter file dialog failure on macOS 12 Monterey
  when using the Tk 8.6.11 provided by python.org macOS installers.
  Patch by Marc Culler of the Tk project.

* bpo-34602: When building CPython on macOS with "./configure --with-
  undefined-behavior-sanitizer --with-pydebug", the stack size is now
  quadrupled to allow for the entire test suite to pass.


IDLE
----

* bpo-45495: Add context keywords ‘case’ and ‘match’ to completions
  list.

* bpo-45296: On Windows, change exit/quit message to suggest Ctrl-D,
  which works, instead of <Ctrl-Z Return>, which does not work in
  IDLE.

* bpo-45193: Make completion boxes appear on Ubuntu again.


Tools/Demos
-----------

* bpo-44786: Fix a warning in regular expression in the c-analyzer
  script.


C API
-----

* bpo-39026: Fix Python.h to build C extensions with Xcode: remove a
  relative include from "Include/cpython/pystate.h".

* bpo-45307: Restore the private C API function
  "_PyImport_FindExtensionObject()". It will be removed in Python
  3.11.

* bpo-44687: "BufferedReader.peek()" no longer raises "ValueError"
  when the entire file has already been buffered.

* bpo-44751: Remove "crypt.h" include from the public "Python.h"
  header.


Python 3.10.0 final
===================

*Release date: 2021-10-04*


Core and Builtins
-----------------

* bpo-45121: Fix issue where "Protocol.__init__" raises
  "RecursionError" when it’s called directly or via "super()". Patch
  provided by Yurii Karabas.


Library
-------

* bpo-45234: Fixed a regression in "copyfile()", "copy()", "copy2()"
  raising "FileNotFoundError" when source is a directory, which should
  raise "IsADirectoryError"


Documentation
-------------

* bpo-45216: Remove extra documentation listing methods in "difflib".
  It was rendering twice in pydoc and was outdated in some places.

* bpo-45024: "collections.abc" documentation has been expanded to
  explicitly cover how instance and subclass checks work, with
  additional doctest examples and an exhaustive list of ABCs which
  test membership purely by presence of the right *special method*s.
  Patch by Raymond Hettinger.


Tests
-----

* bpo-45128: Fix "test_multiprocessing_fork" failure due to
  "test_logging" and "sys.modules" manipulation.

* bpo-44860: Update "test_sysconfig.test_user_similar()" for the
  posix_user scheme: "platlib" doesn’t use "sys.platlibdir". Patch by
  Victor Stinner.


Build
-----

* bpo-45067: The ncurses function extended_color_content was
  introduced in 2017

  (https://invisible-island.net/ncurses/NEWS.html#index-t20170401).
  The

  ncurses-devel package in CentOS 7 had a older version ncurses
  resulted in compilation error.  For compiling ncurses with extended
  color support, we verify the version of the ncurses library >=
  20170401.


IDLE
----

* bpo-45193: Make completion boxes appear on Ubuntu again.


C API
-----

* bpo-45307: Restore the private C API function
  "_PyImport_FindExtensionObject()". It will be removed in Python
  3.11.


Python 3.10.0 release candidate 2
=================================

*Release date: 2021-09-07*


Security
--------

* bpo-42278: Replaced usage of "tempfile.mktemp()" with
  "TemporaryDirectory" to avoid a potential race condition.

* bpo-44394: Update the vendored copy of libexpat to 2.4.1 (from
  2.2.8) to get the fix for the CVE-2013-0340 “Billion Laughs”
  vulnerability. This copy is most used on Windows and macOS.

* bpo-43124: Made the internal "putcmd" function in "smtplib" sanitize
  input for presence of "\r" and "\n" characters to avoid (unlikely)
  command injection.


Core and Builtins
-----------------

* bpo-45123: Fix PyAiter_Check to only check for the __anext__
  presence (not for __aiter__). Rename PyAiter_Check to PyAIter_Check,
  PyObject_GetAiter -> PyObject_GetAIter.

* bpo-45018: Fixed pickling of range iterators that iterated for over
  2**32 times.

* bpo-45000: A "SyntaxError" is now raised when trying to delete
  "__debug__". Patch by Dong-hee Na.

* bpo-44963: Implement "send()" and "throw()" methods for
  "anext_awaitable" objects. Patch by Pablo Galindo.

* bpo-44962: Fix a race in WeakKeyDictionary, WeakValueDictionary and
  WeakSet when two threads attempt to commit the last pending removal.
  This fixes asyncio.create_task and fixes a data loss in asyncio.run
  where shutdown_asyncgens is not run

* bpo-44954: Fixed a corner case bug where the result of
  "float.fromhex('0x.8p-1074')" was rounded the wrong way.

* bpo-44947: Refine the syntax error for trailing commas in import
  statements. Patch by Pablo Galindo.

* bpo-44698: Restore behaviour of complex exponentiation with integer-
  valued exponent of type "float" or "complex".

* bpo-44885: Correct the ast locations of f-strings with format specs
  and repeated expressions. Patch by Pablo Galindo

* bpo-44872: Use new trashcan macros (Py_TRASHCAN_BEGIN/END) in
  frameobject.c instead of the old ones (Py_TRASHCAN_SAFE_BEGIN/END).

* bpo-33930: Fix segmentation fault with deep recursion when cleaning
  method objects. Patch by Augusto Goulart and Pablo Galindo.

* bpo-25782: Fix bug where "PyErr_SetObject" hangs when the current
  exception has a cycle in its context chain.

* bpo-44856: Fix reference leaks in the error paths of
  "update_bases()" and "__build_class__". Patch by Pablo Galindo.

* bpo-44838: Fixed a bug that was causing the parser to raise an
  incorrect custom "SyntaxError" for invalid ‘if’ expressions. Patch
  by Pablo Galindo.

* bpo-44584: The threading debug ("PYTHONTHREADDEBUG" environment
  variable) is deprecated in Python 3.10 and will be removed in Python
  3.12. This feature requires a debug build of Python. Patch by Victor
  Stinner.

* bpo-39091: Fix crash when using passing a non-exception to a
  generator’s "throw()" method. Patch by Noah Oxer


Library
-------

* bpo-45081: Fix issue when dataclasses that inherit from
  "typing.Protocol" subclasses have wrong "__init__". Patch provided
  by Yurii Karabas.

* bpo-41620: "run()" now always return a "TestResult" instance.
  Previously it returned "None" if the test class or method was
  decorated with a skipping decorator.

* bpo-43913: Fix bugs in cleaning up classes and modules in
  "unittest":

  * Functions registered with "addModuleCleanup()" were not called
    unless the user defines "tearDownModule()" in their test module.

  * Functions registered with "addClassCleanup()" were not called if
    "tearDownClass" is set to "None".

  * Buffering in "TestResult" did not work with functions registered
    with "addClassCleanup()" and "addModuleCleanup()".

  * Errors in functions registered with "addClassCleanup()" and
    "addModuleCleanup()" were not handled correctly in buffered and
    debug modes.

  * Errors in "setUpModule()" and functions registered with
    "addModuleCleanup()" were reported in wrong order.

  * And several lesser bugs.

* bpo-45030: Fix integer overflow in pickling and copying the range
  iterator.

* bpo-45001: Made email date parsing more robust against malformed
  input, namely a whitespace-only "Date:" header. Patch by Wouter
  Bolsterlee.

* bpo-44449: Fix a crash in the signal handler of the "faulthandler"
  module: no longer modify the reference count of frame objects. Patch
  by Victor Stinner.

* bpo-44955: Method "stopTestRun()" is now always called in pair with
  method "startTestRun()" for "TestResult" objects implicitly created
  in "run()". Previously it was not called for test methods and
  classes decorated with a skipping decorator.

* bpo-44935: "subprocess" on Solaris now also uses "os.posix_spawn()"
  for better performance.

* bpo-44911: "IsolatedAsyncioTestCase" will no longer throw an
  exception while cancelling leaked tasks. Patch by Bar Harel.

* bpo-44524: Make exception message more useful when subclass from
  typing special form alias. Patch provided by Yurii Karabas.

* bpo-38956: "argparse.BooleanOptionalAction"’s default value is no
  longer printed twice when used with
  "argparse.ArgumentDefaultsHelpFormatter".

* bpo-44860: Fix the "posix_user" scheme in "sysconfig" to not depend
  on "sys.platlibdir".

* bpo-44581: Upgrade bundled pip to 21.2.3 and setuptools to 57.4.0

* bpo-44849: Fix the "os.set_inheritable()" function on FreeBSD 14 for
  file descriptor opened with the "O_PATH" flag: ignore the "EBADF"
  error on "ioctl()", fallback on the "fcntl()" implementation. Patch
  by Victor Stinner.

* bpo-44605: The @functools.total_ordering() decorator now works with
  metaclasses.

* bpo-44524: Fixed an issue wherein the "__name__" and "__qualname__"
  attributes of subscribed specialforms could be "None".

* bpo-44822: "sqlite3" user-defined functions and aggregators
  returning "strings" with embedded NUL characters are no longer
  truncated. Patch by Erlend E. Aasland.

* bpo-44801: Ensure that the "ParamSpec" variable in Callable can only
  be substituted with a parameters expression (a list of types, an
  ellipsis, ParamSpec or Concatenate).

* bpo-27334: The "sqlite3" context manager now performs a rollback
  (thus releasing the database lock) if commit failed.  Patch by Luca
  Citi and Erlend E. Aasland.

* bpo-41402: Fix "email.message.EmailMessage.set_content()" when
  called with binary data and "7bit" content transfer encoding.

* bpo-32695: The *compresslevel* and *preset* keyword arguments of
  "tarfile.open()" are now both documented and tested.

* bpo-34990: Fixed a Y2k38 bug in the compileall module where it would
  fail to compile files with a modification time after the year 2038.

* bpo-38840: Fix "test___all__" on platforms lacking a shared memory
  implementation.

* bpo-26228: pty.spawn no longer hangs on FreeBSD, macOS, and Solaris.

* bpo-33349: lib2to3 now recognizes async generators everywhere.


Documentation
-------------

* bpo-44957: Promote PEP 604 union syntax by using it where possible.
  Also, mention "X | Y" more prominently in section about "Union" and
  mention "X | None" at all in section about "Optional".

* bpo-44903: Removed the othergui.rst file, any references to it, and
  the list of GUI frameworks in the FAQ. In their place I’ve added
  links to the Python Wiki "page on GUI frameworks".

* bpo-33479: Tkinter documentation has been greatly expanded with new
  “Architecture” and “Threading model” sections.

* bpo-36700: "base64" RFC references were updated to point to **RFC
  4648**; a section was added to point users to the new “security
  considerations” section of the RFC.

* bpo-44756: Reverted automated virtual environment creation on "make
  html" when building documentation. It turned out to be disruptive
  for downstream distributors.

* bpo-42958: Updated the docstring and docs of "filecmp.cmp()" to be
  more accurate and less confusing especially in respect to *shallow*
  arg.

* bpo-43066: Added a warning to "zipfile" docs: filename arg with a
  leading slash may cause archive to be un-openable on Windows
  systems.

* bpo-39452: Rewrote "Doc/library/__main__.rst". Broadened scope of
  the document to explicitly discuss and differentiate between
  "__main__.py" in packages versus the "__name__ == '__main__'"
  expression (and the idioms that surround it).

* bpo-27752: Documentation of csv.Dialect is more descriptive.

* bpo-41576: document BaseException in favor of bare except

* bpo-39498: Add a “Security Considerations” index which links to
  standard library modules that have explicitly documented security
  considerations.

* bpo-33479: Remove the unqualified claim that tkinter is threadsafe.
  It has not been true for several years and likely never was. An
  explanation of what is true may be added later, after more
  discussion, and possibly after patching _tkinter.c,


Tests
-----

* bpo-45052: "WithProcessesTestSharedMemory.test_shared_memory_basics"
  test was ignored, because "self.assertEqual(sms.size, sms2.size)"
  line was failing. It is now removed and test is unskipped.

  The main motivation for this line to be removed from the test is
  that the "size" of "SharedMemory" is not ever guaranteed to be the
  same. It is decided by the platform.

* bpo-45042: Fixes that test classes decorated with
  "@hashlib_helper.requires_hashdigest" were skipped all the time.

* bpo-45011: Made tests relying on the "_asyncio" C extension module
  optional to allow running on alternative Python implementations.
  Patch by Serhiy Storchaka.

* bpo-44949: Fix auto history tests of test_readline: sometimes, the
  newline character is not written at the end, so don’t expect it in
  the output.

* bpo-44891: Tests were added to clarify "id()" is preserved when "obj
  * 1" is used on "str" and "bytes" objects. Patch by Nikita Sobolev.

* bpo-44852: Add ability to wholesale silence DeprecationWarnings
  while running the regression test suite.

* bpo-40928: Notify users running test_decimal regression tests on
  macOS of potential harmless “malloc can’t allocate region” messages
  spewed by test_decimal.


Windows
-------

* bpo-45007: Update to OpenSSL 1.1.1l in Windows build


macOS
-----

* bpo-45007: Update macOS installer builds to use OpenSSL 1.1.1l.

* bpo-44689: "ctypes.util.find_library()" now works correctly on macOS
  11 Big Sur even if Python is built on an older version of macOS.
  Previously, when built on older macOS systems, "find_library" was
  not able to find  macOS system libraries when running on Big Sur due
  to changes in  how system libraries are stored.


Python 3.10.0 release candidate 1
=================================

*Release date: 2021-08-02*


Security
--------

* bpo-44600: Fix incorrect line numbers while tracing some failed
  patterns in match statements. Patch by Charles Burkland.


Core and Builtins
-----------------

* bpo-44792: Improve syntax errors for if expressions. Patch by Miguel
  Brito

* bpo-34013: Generalize the invalid legacy statement custom error
  message (like the one generated when “print” is called without
  parentheses) to include more generic expressions. Patch by Pablo
  Galindo

* bpo-44732: Rename "types.Union" to "types.UnionType".

* bpo-44698: Fix undefined behaviour in complex object exponentiation.

* bpo-44653: Support "typing" types in parameter substitution in the
  union type.

* bpo-44676: Add ability to serialise "types.Union" objects. Patch
  provided by Yurii Karabas.

* bpo-44633: Parameter substitution of the union type with wrong types
  now raises "TypeError" instead of returning "NotImplemented".

* bpo-44662: Add "__module__" to "types.Union". This also fixes
  "types.Union" issues with "typing.Annotated". Patch provided by
  Yurii Karabas.

* bpo-44655: Include the name of the type in unset __slots__ attribute
  errors. Patch by Pablo Galindo

* bpo-44655: Don’t include a missing attribute with the same name as
  the failing one when offering suggestions for missing attributes.
  Patch by Pablo Galindo

* bpo-44646: Fix the hash of the union type: it no longer depends on
  the order of arguments.

* bpo-44636: Collapse union of equal types. E.g. the result of "int |
  int" is now "int". Fix comparison of the union type with non-
  hashable objects. E.g. "int | str == {}" no longer raises a
  TypeError.

* bpo-44635: Convert "None" to "type(None)" in the union type
  constructor.

* bpo-44589: Mapping patterns in "match" statements with two or more
  equal literal keys will now raise a "SyntaxError" at compile-time.

* bpo-44606: Fix "__instancecheck__" and "__subclasscheck__" for the
  union type.

* bpo-42073: The "@classmethod" decorator can now wrap other
  classmethod-like descriptors.

* bpo-44490: "typing" now searches for type parameters in
  "types.Union" objects. "get_type_hints" will also properly resolve
  annotations with nested "types.Union" objects. Patch provided by
  Yurii Karabas.

* bpo-44490: Add "__parameters__" attribute and "__getitem__" operator
  to "types.Union". Patch provided by Yurii Karabas.

* bpo-44472: Fix ltrace functionality when exceptions are raised.
  Patch by Pablo Galindo


Library
-------

* bpo-44806: Non-protocol subclasses of "typing.Protocol" ignore now
  the "__init__" method inherited from protocol base classes.

* bpo-44793: Fix checking the number of arguments when subscribe a
  generic type with "ParamSpec" parameter.

* bpo-44784: In importlib.metadata tests, override warnings behavior
  under expected DeprecationWarnings (importlib_metadata 4.6.3).

* bpo-44667: The "tokenize.tokenize()" doesn’t incorrectly generate a
  "NEWLINE" token if the source doesn’t end with a new line character
  but the last line is a comment, as the function is already
  generating a "NL" token. Patch by Pablo Galindo

* bpo-44752: "rcompleter" does not call "getattr()" on "property"
  objects to avoid the side-effect of  evaluating the corresponding
  method.

* bpo-44720: "weakref.proxy" objects referencing non-iterators now
  raise "TypeError" rather than dereferencing the null "tp_iternext"
  slot and crashing.

* bpo-44704: The implementation of "collections.abc.Set._hash()" now
  matches that of "frozenset.__hash__()".

* bpo-44666: Fixed issue in "compileall.compile_file()" when
  "sys.stdout" is redirected. Patch by Stefan Hölzl.

* bpo-42854: Fixed a bug in the "_ssl" module that was throwing
  "OverflowError" when using "_ssl._SSLSocket.write()" and
  "_ssl._SSLSocket.read()" for a big value of the "len" parameter.
  Patch by Pablo Galindo

* bpo-44353: Refactor "typing.NewType" from function into callable
  class. Patch provided by Yurii Karabas.

* bpo-44524: Add missing "__name__" and "__qualname__" attributes to
  "typing" module classes. Patch provided by Yurii Karabas.

* bpo-40897: Give priority to using the current class constructor in
  "inspect.signature()". Patch by Weipeng Hong.

* bpo-44648: Fixed wrong error being thrown by "inspect.getsource()"
  when examining a class in the interactive session. Instead of
  "TypeError", it should be "OSError" with appropriate error message.

* bpo-44608: Fix memory leak in "_tkinter._flatten()" if it is called
  with a sequence or set, but not list or tuple.

* bpo-44559: [Enum] module reverted to 3.9; 3.10 changes pushed until
  3.11

* bpo-41928: Update "shutil.copyfile()" to raise "FileNotFoundError"
  instead of confusing "IsADirectoryError" when a path ending with a
  "os.path.sep" does not exist; "shutil.copy()" and "shutil.copy2()"
  are also affected.

* bpo-44566: handle StopIteration subclass raised from
  @contextlib.contextmanager generator

* bpo-41249: Fixes "TypedDict" to work with "typing.get_type_hints()"
  and postponed evaluation of annotations across modules.

* bpo-44461: Fix bug with "pdb"’s handling of import error due to a
  package which does not have a "__main__" module

* bpo-43625: Fix a bug in the detection of CSV file headers by
  "csv.Sniffer.has_header()" and improve documentation of same.

* bpo-42892: Fixed an exception thrown while parsing a malformed
  multipart email by "email.message.EmailMessage".

* bpo-27827: "pathlib.PureWindowsPath.is_reserved()" now identifies a
  greater range of reserved filenames, including those with trailing
  spaces or colons.

* bpo-38741: "configparser": using ‘]’ inside a section header will no
  longer cut the section name short at the ‘]’

* bpo-27513: "email.utils.getaddresses()" now accepts
  "email.header.Header" objects along with string values. Patch by
  Zackery Spytz.

* bpo-29298: Fix "TypeError" when required subparsers without "dest"
  do not receive arguments. Patch by Anthony Sottile.


Documentation
-------------

* bpo-44740: Replaced occurences of uppercase “Web” and “Internet”
  with lowercase versions per the 2016 revised Associated Press Style
  Book.

* bpo-44693: Update the definition of __future__ in the glossary by
  replacing the confusing word “pseudo-module” with a more accurate
  description.

* bpo-35183: Add typical examples to os.path.splitext docs

* bpo-30511: Clarify that "shutil.make_archive()" is not thread-safe
  due to reliance on changing the current working directory.

* bpo-44561: Update of three expired hyperlinks in
  Doc/distributing/index.rst: “Project structure”, “Building and
  packaging the project”, and “Uploading the project to the Python
  Packaging Index”.

* bpo-44613: importlib.metadata is no longer provisional.

* bpo-44544: List all kwargs for "textwrap.wrap()", "textwrap.fill()",
  and "textwrap.shorten()". Now, there are nav links to attributes of
  "TextWrap", which makes navigation much easier while minimizing
  duplication in the documentation.

* bpo-44453: Fix documentation for the return type of
  "sysconfig.get_path()".


Tests
-----

* bpo-44734: Fixed floating point precision issue in turtle tests.

* bpo-44708: Regression tests, when run with -w, are now re-running
  only the affected test methods instead of re-running the entire test
  file.

* bpo-44647: Added a permanent Unicode-valued environment variable to
  regression tests to ensure they handle this use case in the future.
  If your test environment breaks because of that, report a bug to us,
  and temporarily set PYTHONREGRTEST_UNICODE_GUARD=0 in your test
  environment.

* bpo-44515: Adjust recently added contextlib tests to avoid assuming
  the use of a refcounted GC


Windows
-------

* bpo-44572: Avoid consuming standard input in the "platform" module

* bpo-40263: This is a follow-on bug from
  https://bugs.python.org/issue26903. Once that is applied we run into
  an off-by-one assertion problem. The assert was not correct.


macOS
-----

* bpo-41972: The framework build’s user header path in sysconfig is
  changed to add a ‘pythonX.Y’ component to match distutils’s
  behavior.

* bpo-34932: Add socket.TCP_KEEPALIVE support for macOS. Patch by
  Shane Harvey.


Tools/Demos
-----------

* bpo-44756: In the Makefile for documentation ("Doc/Makefile"), the
  "build" rule is dependent on the "venv" rule. Therefore, "html",
  "latex", and other build-dependent rules are also now dependent on
  "venv". The "venv" rule only performs an action if "$(VENVDIR)" does
  not exist. "Doc/README.rst" was updated; most users now only need to
  type "make html".


C API
-----

* bpo-41103: Reverts removal of the old buffer protocol because they
  are part of stable ABI.

* bpo-42747: The "Py_TPFLAGS_HAVE_VERSION_TAG" type flag now does
  nothing. The "Py_TPFLAGS_HAVE_AM_SEND" flag (which was added in
  3.10) is removed. Both were unnecessary because it is not possible
  to have type objects with the relevant fields missing.


Python 3.10.0 beta 4
====================

*Release date: 2021-07-10*


Security
--------

* bpo-41180: Add auditing events to the "marshal" module, and stop
  raising "code.__init__" events for every unmarshalled code object.
  Directly instantiated code objects will continue to raise an event,
  and audit event handlers should inspect or collect the raw marshal
  data. This reduces a significant performance overhead when loading
  from ".pyc" files.


Core and Builtins
-----------------

* bpo-44562: Remove uses of "PyObject_GC_Del()" in error path when
  initializing "types.GenericAlias".

* bpo-41486: Fix a memory consumption and copying performance
  regression in earlier 3.10 beta releases if someone used an output
  buffer larger than 4GiB with zlib.decompress on input data that
  expands that large.

* bpo-44553: Implement GC methods for "types.Union" to break reference
  cycles and prevent memory leaks.

* bpo-44523: Remove the pass-through for "hash()" of "weakref.proxy"
  objects to prevent unintended consequences when the original
  referred object dies while the proxy is part of a hashable object.
  Patch by Pablo Galindo.

* bpo-44483: Fix a crash in "types.Union" objects when creating a
  union of an object with bad "__module__" field.

* bpo-44297: Make sure that the line number is set when entering a
  comprehension scope. Ensures that backtraces inclusing generator
  expressions show the correct line number.

* bpo-44456: Improve the syntax error when mixing positional and
  keyword patterns. Patch by Pablo Galindo.

* bpo-44368: Improve syntax errors for invalid “as” targets. Patch by
  Pablo Galindo

* bpo-44317: Improve tokenizer error with improved locations. Patch by
  Pablo Galindo.

* bpo-43667: Improve Unicode support in non-UTF locales on Oracle
  Solaris. This issue does not affect other Solaris systems.


Library
-------

* bpo-44558: Make the implementation consistency of "indexOf()"
  between C and Python versions. Patch by Dong-hee Na.

* bpo-34798: Break up paragraph about "pprint.PrettyPrinter"
  construction parameters to make it easier to read.

* bpo-44516: Update vendored pip to 21.1.3

* bpo-44468: "typing.get_type_hints()" now finds annotations in
  classes and base classes with unexpected "__module__". Previously,
  it skipped those MRO elements.

* bpo-43977: Set the proper "Py_TPFLAGS_MAPPING" and
  "Py_TPFLAGS_SEQUENCE" flags for subclasses created before a parent
  has been registered as a "collections.abc.Mapping" or
  "collections.abc.Sequence".

* bpo-44482: Fix very unlikely resource leak in "glob" in alternate
  Python implementations.

* bpo-44466: The "faulthandler" module now detects if a fatal error
  occurs during a garbage collector collection. Patch by Victor
  Stinner.

* bpo-44404: "tkinter"’s "after()" method now supports callables
  without the "__name__" attribute.

* bpo-44458: "BUFFER_BLOCK_SIZE" is now declared static, to avoid
  linking collisions when bz2, lmza or zlib are statically linked.

* bpo-44464: Remove exception for flake8 in deprecated
  importlib.metadata interfaces. Sync with importlib_metadata 4.6.

* bpo-44446: Take into account that "lineno" might be "None" in
  "traceback.FrameSummary".

* bpo-44439: Fix in "bz2.BZ2File.write()" / "lzma.LZMAFile.write()"
  methods, when the input data is an object that supports the buffer
  protocol, the file length may be wrong.

* bpo-44434: _thread.start_new_thread() no longer calls
  PyThread_exit_thread() explicitly at the thread exit, the call was
  redundant. On Linux with the glibc, pthread_exit() aborts the whole
  process if dlopen() fails to open libgcc_s.so file (ex: EMFILE
  error). Patch by Victor Stinner.

* bpo-44395: Fix "as_string()" to pass unixfrom properly. Patch by
  Dong-hee Na.

* bpo-34266: Handle exceptions from parsing the arg of "pdb"’s
  run/restart command.

* bpo-44077: It’s now possible to receive the type of service (ToS),
  a.k.a. differentiated services (DS), a.k.a. differenciated services
  code point (DSCP) and excplicit congestion notification (ECN) IP
  header fields with "socket.IP_RECVTOS".

* bpo-43024: Improve the help signature of
  "traceback.print_exception()", "traceback.format_exception()" and
  "traceback.format_exception_only()".

* bpo-30256: Pass multiprocessing BaseProxy argument "manager_owned"
  through AutoProxy.


Documentation
-------------

* bpo-44558: Match the docstring and python implementation of
  "countOf()" to the behavior of its c implementation.

* bpo-38062: Clarify that atexit uses equality comparisons internally.

* bpo-40620: Convert examples in tutorial controlflow.rst section 4.3
  to be interpreter-demo style.

* bpo-13814: In the Design FAQ, answer “Why don’t generators support
  the with statement?”

* bpo-41621: Document that "collections.defaultdict" parameter
  "default_factory" defaults to None and is positional-only.


Tests
-----

* bpo-44287: Fix asyncio test_popen() of test_windows_utils by using a
  longer timeout. Use military grade battle-tested
  "test.support.SHORT_TIMEOUT" timeout rather than a hardcoded timeout
  of 10 seconds: it’s 30 seconds by default, but it is made longer on
  slow buildbots. Patch by Victor Stinner.

* bpo-44451: Reset "DeprecationWarning" filters in "test.test_importl
  ib.test_metadata_api.APITests.test_entry_points_by_index" to avoid
  "StopIteration" error if "DeprecationWarnings" are ignored.

* bpo-30256: Add test for nested queues when using "multiprocessing"
  shared objects "AutoProxy[Queue]" inside "ListProxy" and "DictProxy"


Build
-----

* bpo-44535: Enable building using a Visual Studio 2022 install on
  Windows.

* bpo-43298: Improved error message when building without a Windows
  SDK installed.


Windows
-------

* bpo-44582: Accelerate speed of "mimetypes" initialization using a
  native implementation of the registry scan.

* bpo-41299: Fix 16ms jitter when using timeouts in "threading", such
  as with "threading.Lock.acquire()" or "threading.Condition.wait()".


C API
-----

* bpo-44441: "Py_RunMain()" now resets "PyImport_Inittab" to its
  initial value at exit. It must be possible to call
  "PyImport_AppendInittab()" or "PyImport_ExtendInittab()" at each
  Python initialization. Patch by Victor Stinner.

* bpo-40939: Removed documentation for the removed "PyParser_*" C API.


Python 3.10.0 beta 3
====================

*Release date: 2021-06-17*


Core and Builtins
-----------------

* bpo-44409: Fix error location information for tokenizer errors
  raised on initialization of the tokenizer. Patch by Pablo Galindo.

* bpo-44396: Fix a possible crash in the tokenizer when raising syntax
  errors for unclosed strings. Patch by Pablo Galindo.

* bpo-44349: Fix an edge case when displaying text from files with
  encoding in syntax errors. Patch by Pablo Galindo.

* bpo-44335: Fix a regression when identifying incorrect characters in
  syntax errors. Patch by Pablo Galindo

* bpo-44304: Fix a crash in the "sqlite3" module that happened when
  the garbage collector clears "sqlite.Statement" objects. Patch by
  Pablo Galindo

* bpo-44305: Improve error message for "try" blocks without "except"
  or "finally" blocks. Patch by Pablo Galindo.

* bpo-43833: Emit a deprecation warning if the numeric literal is
  immediately followed by one of keywords: and, else, for, if, in, is,
  or. Raise a syntax error with more informative message if it is
  immediately followed by other keyword or identifier.

* bpo-11105: When compiling "ast.AST" objects with recursive
  references through "compile()", the interpreter doesn’t crash
  anymore instead it raises a "RecursionError".


Library
-------

* bpo-42972: The _thread.RLock type now fully implement the GC
  protocol: add a traverse function and the "Py_TPFLAGS_HAVE_GC" flag.
  Patch by Victor Stinner.

* bpo-44422: The "threading.enumerate()" function now uses a reentrant
  lock to prevent a hang on reentrant call. Patch by Victor Stinner.

* bpo-44389: Fix deprecation of "ssl.OP_NO_TLSv1_3"

* bpo-44362: Improve "ssl" module’s deprecation messages, error
  reporting, and documentation for deprecations.

* bpo-44342: [Enum] Change pickling from by-value to by-name.

* bpo-44356: [Enum] Allow multiple data-type mixins if they are all
  the same.

* bpo-44351: Restore back "parse_makefile()" in "distutils.sysconfig"
  because it behaves differently than the similar implementation in
  "sysconfig".

* bpo-44242: Remove missing flag check from Enum creation and move
  into a "verify" decorator.

* bpo-44246: In "importlib.metadata", restore compatibility in the
  result from "Distribution.entry_points" ("EntryPoints") to honor
  expectations in older implementations and issuing deprecation
  warnings for these cases: A. "EntryPoints" objects are once again
  mutable, allowing   for "sort()" and other list-based mutation
  operations.   Avoid deprecation warnings by casting to a   mutable
  sequence (e.g. "list(dist.entry_points).sort()"). B. "EntryPoints"
  results once again allow   for access by index. To avoid deprecation
  warnings,   cast the result to a Sequence first   (e.g.
  "tuple(dist.entry_points)[0]").

* bpo-44246: In importlib.metadata.entry_points, de-duplication of
  distributions no longer requires loading the full metadata for
  PathDistribution objects, improving entry point loading performance
  by ~10x.

* bpo-43853: Improved string handling for "sqlite3" user-defined
  functions and aggregates:

  * It is now possible to pass strings with embedded null characters
    to UDFs

  * Conversion failures now correctly raise "MemoryError"

  Patch by Erlend E. Aasland.

* bpo-43318: Fix a bug where "pdb" does not always echo cleared
  breakpoints.

* bpo-37022: "pdb" now displays exceptions from "repr()" with its "p"
  and "pp" commands.


Documentation
-------------

* bpo-44392: Added a new section in the C API documentation for types
  used in type hinting.  Documented "Py_GenericAlias" and
  "Py_GenericAliasType".

* bpo-38291: Mark "typing.io" and "typing.re" as deprecated since
  Python 3.8 in the documentation. They were never properly supported
  by type checkers.

* bpo-44322: Document that SyntaxError args have a details tuple and
  that details are adjusted for errors in f-string field replacement
  expressions.


Tests
-----

* bpo-44363: Account for address sanitizer in test_capi. test_capi now
  passes when run GCC address sanitizer.

* bpo-43921: Fix test_ssl.test_wrong_cert_tls13(): use
  "suppress_ragged_eofs=False", since "read()" can raise
  "ssl.SSLEOFError" on Windows. Patch by Victor Stinner.

* bpo-43921: Fix test_pha_required_nocert() of test_ssl: catch two
  more EOF cases (when the "recv()" method returns an empty string).
  Patch by Victor Stinner.


Build
-----

* bpo-44381: The Windows build now accepts "EnableControlFlowGuard"
  set to "guard" to enable CFG.


IDLE
----

* bpo-40128: Mostly fix completions on macOS when not using tcl/tk
  8.6.11 (as with 3.9). The added update_idletask call should be
  harmless and possibly helpful otherwise.

* bpo-33962: Move the indent space setting from the Font tab to the
  new Windows tab. Patch by Mark Roseman and Terry Jan Reedy.

* bpo-40468: Split the settings dialog General tab into Windows and
  Shell/ED tabs. Move help sources, which extend the Help menu, to the
  Extensions tab. Make space for new options and shorten the dialog.
  The latter makes the dialog better fit small screens.


C API
-----

* bpo-43795: The list in Contents of Limited API now shows the public
  name "PyFrameObject" rather than "_frame". The non-existing entry
  "_node" no longer appears in the list.

* bpo-44378: "Py_IS_TYPE()" no longer uses "Py_TYPE()" to avoid a
  compiler warning: no longer cast "const PyObject*" to "PyObject*".
  Patch by Victor Stinner.


Python 3.10.0 beta 2
====================

*Release date: 2021-05-31*


Security
--------

* bpo-44022: mod:"http.client" now avoids infinitely reading potential
  HTTP headers after a "100 Continue" status response from the server.


Core and Builtins
-----------------

* bpo-43667: Improve Unicode support in non-UTF locales on Oracle
  Solaris. This issue does not affect other Solaris systems.

* bpo-44232: Fix a regression in "type()" when a metaclass raises an
  exception. The C function "type_new()" must properly report the
  exception when a metaclass constructor raises an exception and the
  winner class is not the metaclass. Patch by Victor Stinner.

* bpo-44201: Avoid side effects of checking for specialized syntax
  errors in the REPL that was causing it to ask for extra tokens after
  a syntax error had been detected. Patch by Pablo Galindo

* bpo-44184: Fix a crash at Python exit when a deallocator function
  removes the last strong reference to a heap type. Patch by Victor
  Stinner.

* bpo-44180: The parser doesn’t report generic syntax errors that
  happen in a position further away that the one it reached in the
  first pass. Patch by Pablo Galindo

* bpo-44168: Fix error message in the parser involving keyword
  arguments with invalid expressions. Patch by Pablo Galindo

* bpo-44143: Fixed a crash in the parser that manifest when raising
  tokenizer errors when an existing exception was present. Patch by
  Pablo Galindo.

* bpo-44114: Fix incorrect dictkeys_reversed and dictitems_reversed
  function signatures in C code, which broke webassembly builds.

* bpo-43149: Corrent the syntax error message regarding multiple
  exception types to not refer to “exception groups”. Patch by Pablo
  Galindo

* bpo-44056: Syntax errors when default "except" is not the last
  "except"  are reported with the correct location. Patch by Mark
  Shannon.

* bpo-43822: The parser will prioritize tokenizer errors over custom
  syntax errors when raising exceptions. Patch by Pablo Galindo.

* bpo-28146: Fix a confusing error message in "str.format()".


Library
-------

* bpo-44254: On Mac, give turtledemo button text a color that works on
  both light or dark background.  Programmers cannot control the
  latter.

* bpo-38693: Prefer f-strings to ".format" in importlib.resources.

* bpo-33693: Importlib.metadata now prefers f-strings to .format.

* bpo-44241: Incorporate minor tweaks from importlib_metadata 4.1:
  SimplePath protocol, support for Metadata 2.2.

* bpo-44210: Make importlib.metadata._meta.PackageMetadata public.

* bpo-43643: Declare readers.MultiplexedPath.name as a property per
  the spec.

* bpo-33433: For IPv4 mapped IPv6 addresses (**RFC 4291** Section
  2.5.5.2), the "ipaddress.IPv6Address.is_private" check is deferred
  to the mapped IPv4 address. This solves a bug where public mapped
  IPv4 addresses were considered private by the IPv6 check.

* bpo-44145: "hmac" computations were not releasing the GIL while
  calling the OpenSSL "HMAC_Update" C API (a new feature in 3.9).
  This unintentionally prevented parallel computation as other
  "hashlib" algorithms support.

* bpo-37788: Fix a reference leak when a Thread object is never
  joined.

* bpo-38908: Subclasses of "typing.Protocol" which only have data
  variables declared will now raise a "TypeError" when checked with
  "isinstance" unless they are decorated with "runtime_checkable()".
  Previously, these checks passed silently. Patch provided by Yurii
  Karabas.

* bpo-44098: "typing.ParamSpec" will no longer be found in the
  "__parameters__" of most "typing" generics except in valid use
  locations specified by **PEP 612**. This prevents incorrect usage
  like "typing.List[P][int]". This change means incorrect usage which
  may have passed silently in 3.10 beta 1 and earlier will now error.

* bpo-44089: Allow subclassing "csv.Error" in 3.10 (it was allowed in
  3.9 and earlier but was disallowed in early versions of 3.10).

* bpo-44059: Register the SerenityOS Browser in the "webbrowser"
  module.

* bpo-36515: The "hashlib" module no longer does unaligned memory
  accesses when compiled for ARM platforms.

* bpo-44018: random.seed() no longer mutates bytearray inputs.

* bpo-38352: Add "IO", "BinaryIO", "TextIO", "Match", and "Pattern" to
  "typing.__all__". Patch by Jelle Zijlstra.

* bpo-43972: When "http.server.SimpleHTTPRequestHandler" sends a "301
  (Moved Permanently)" for a directory path not ending with "/", add a
  "Content-Length: 0" header. This improves the behavior for certain
  clients.

* bpo-28528: Fix a bug in "pdb" where "checkline()" raises
  "AttributeError" if it is called after "reset()".

* bpo-43650: Fix "MemoryError" in "shutil.unpack_archive()" which
  fails inside "shutil._unpack_zipfile()" on large files. Patch by
  Igor Bolshakov.

* bpo-41730: "DeprecationWarning" is now raised when importing
  "tkinter.tix", which has been deprecated in documentation since
  Python 3.6.


Documentation
-------------

* bpo-42392: Document the deprecation and removal of the "loop"
  parameter for many functions and classes in "asyncio".

* bpo-44195: Corrected references to "TraversableResources" in docs.
  There is no "TraversableReader".

* bpo-41963: Document that "ConfigParser" strips off comments when
  reading configuration files.

* bpo-44072: Correct where in the numeric ABC hierarchy "**" support
  is added, i.e., in numbers.Complex, not numbers.Integral.

* bpo-43558: Add the remark to "dataclasses" documentation that the
  "__init__()" of any base class has to be called in
  "__post_init__()", along with a code example.

* bpo-44025: Clarify when ‘_’ in match statements is a keyword, and
  when not.


Tests
-----

* bpo-31904: Ignore error string case in test_py_compile
  "test_file_not_exists()".

* bpo-42083: Add test to check that "PyStructSequence_NewType" accepts
  a "PyStructSequence_Desc" with "doc" field set to "NULL".

* bpo-35753: Fix crash in doctest when doctest parses modules that
  include unwrappable functions by skipping those functions.


Build
-----

* bpo-41282: Fix broken "make install" that caused standard library
  extension modules to be unnecessarily and incorrectly rebuilt during
  the install phase of cpython.


Windows
-------

* bpo-42686: Build "sqlite3" with math functions enabled. Patch by
  Erlend E. Aasland.


macOS
-----

* bpo-43109: Allow –with-lto configure option to work with Apple-
  supplied Xcode or Command Line Tools.


IDLE
----

* bpo-41611: Avoid uncaught exceptions in
  "AutoCompleteWindow.winconfig_event()".

* bpo-41611: Fix IDLE sometimes freezing upon tab-completion on macOS.

* bpo-44010: Highlight the new match statement’s soft keywords:
  "match", "case", and "_". However, this highlighting is not perfect
  and will be incorrect in some rare cases, including some "_"-s in
  "case" patterns.

* bpo-44026: Include interpreter’s typo fix suggestions in message
  line for NameErrors and AttributeErrors.  Patch by E. Paine.


Tools/Demos
-----------

* bpo-44074: Make patchcheck automatically detect the correct base
  branch name (previously it was hardcoded to ‘master’)


C API
-----

* bpo-43795: The undocumented function "Py_FrozenMain()" is removed
  from the Limited API.

* bpo-43795: "PyCodec_Unregister()" is now properly exported as a
  function in the Windows Stable ABI DLL.


Python 3.10.0 beta 1
====================

*Release date: 2021-05-03*


Security
--------

* bpo-43434: Creating "sqlite3.Connection" objects now also produces
  "sqlite3.connect" and "sqlite3.connect/handle" auditing events.
  Previously these events were only produced by "sqlite3.connect()"
  calls. Patch by Erlend E. Aasland.

* bpo-43998: The "ssl" module sets more secure cipher suites defaults.
  Ciphers without forward secrecy and with SHA-1 MAC are disabled by
  default. Security level 2 prohibits weak RSA, DH, and ECC keys with
  less than 112 bits of security. "SSLContext" defaults to minimum
  protocol version TLS 1.2. Settings are based on Hynek Schlawack’s
  research.

* bpo-43882: The presence of newline or tab characters in parts of a
  URL could allow some forms of attacks.

  Following the controlling specification for URLs defined by WHATWG
  "urllib.parse()" now removes ASCII newlines and tabs from URLs,
  preventing such attacks.

* bpo-43472: Ensures interpreter-level audit hooks receive the
  "cpython.PyInterpreterState_New" event when called through the
  "_xxsubinterpreters" module.

* bpo-43362: Fix invalid free in _sha3 module. The issue was
  introduced in 3.10.0a1. Python 3.9 and earlier are not affected.

* bpo-43762: Add audit events for "sqlite3.connect/handle()",
  "sqlite3.Connection.enable_load_extension()", and
  "sqlite3.Connection.load_extension()". Patch by Erlend E. Aasland.

* bpo-43756: Add new audit event "glob.glob/2" to incorporate the new
  *root_dir* and *dir_fd* arguments added to "glob.glob()" and
  "glob.iglob()".

* bpo-36384: "ipaddress" module no longer accepts any leading zeros in
  IPv4 address strings. Leading zeros are ambiguous and interpreted as
  octal notation by some libraries. For example the legacy function
  "socket.inet_aton()" treats leading zeros as octal notatation. glibc
  implementation of modern "inet_pton()" does not accept any leading
  zeros. For a while the "ipaddress" module used to accept ambiguous
  leading zeros.

* bpo-43075: Fix Regular Expression Denial of Service (ReDoS)
  vulnerability in "urllib.request.AbstractBasicAuthHandler".  The
  ReDoS-vulnerable regex has quadratic worst-case complexity and it
  allows cause a denial of service when identifying crafted invalid
  RFCs. This ReDoS issue is on the client side and needs remote
  attackers to control the HTTP server.

* bpo-42800: Audit hooks are now fired for frame.f_code,
  traceback.tb_frame, and generator code/frame attribute access.

* bpo-37363: Add audit events to the "http.client" module.


Core and Builtins
-----------------

* bpo-43977: Prevent classes being both a sequence and a mapping when
  pattern matching.

* bpo-43977: Use "tp_flags" on the class object to determine if the
  subject is a sequence or mapping when pattern matching. Avoids the
  need to import "collections.abc" when pattern matching.

* bpo-43892: Restore proper validation of complex literal value
  patterns when parsing "match" blocks.

* bpo-43933: Set frame.f_lineno to the line number of the ‘with’
  kweyword when executing the call to "__exit__".

* bpo-43933: If the current position in a frame has no line number
  then set the f_lineno attribute to None, instead of -1, to conform
  to PEP 626. This should not normally be possible, but might occur in
  some unusual circumstances.

* bpo-43963: Importing the "_signal" module in a subinterpreter has no
  longer side effects.

* bpo-42739: The internal representation of line number tables is
  changed to not use sentinels, and an explicit length parameter is
  added to the out of process API function
  "PyLineTable_InitAddressRange". This makes the handling of line
  number tables more robust in some circumstances.

* bpo-43908: Make "re" types immutable. Patch by Erlend E. Aasland.

* bpo-43908: Make the "array.array" type immutable. Patch by Erlend E.
  Aasland.

* bpo-43901: Change class and module objects to lazy-create empty
  annotations dicts on demand.  The annotations dicts are stored in
  the object’s __dict__ for backwards compatibility.

* bpo-43892: Match patterns now use new dedicated AST nodes
  ("MatchValue", "MatchSingleton", "MatchSequence", "MatchStar",
  "MatchMapping", "MatchClass") rather than reusing expression AST
  nodes. "MatchAs" and "MatchOr" are now defined as pattern nodes
  rather than as expression nodes. Patch by Nick Coghlan.

* bpo-42725: Usage of "await"/"yield"/"yield from" and named
  expressions within an annotation is now forbidden when PEP 563 is
  activated.

* bpo-43754: When performing structural pattern matching (**PEP
  634**), captured names are now left unbound until the *entire*
  pattern has matched successfully.

* bpo-42737: Annotations for complex targets (everything beside simple
  names) no longer cause any runtime effects with "from __future__
  import annotations".

* bpo-43914: "SyntaxError" exceptions raised by the interpreter will
  highlight the full error range of the expression that consistutes
  the syntax error itself, instead of just where the problem is
  detected. Patch by Pablo Galindo.

* bpo-38605: Revert making "from __future__ import annotations" the
  default. This follows the Steering Council decision to postpone PEP
  563 changes to at least Python 3.11. See the original email for more
  information regarding the decision:
  https://mail.python.org/archives/list/python-
  dev@python.org/thread/CLVXXPQ2T2LQ5MP2Y53VVQFCXYWQJHKZ/. Patch by
  Pablo Galindo.

* bpo-43475: Hashes of NaN values now depend on object identity.
  Formerly, they always hashed to 0 even though NaN values are not
  equal to one another.  Having the same hash for unequal values
  caused pile-ups in hash tables.

* bpo-43859: Improve the error message for "IndentationError"
  exceptions. Patch by Pablo Galindo

* bpo-41323: Constant tuple folding in bytecode optimizer now reuses
  tuple in constant table.

* bpo-43846: Data stack usage is much reduced for large literal and
  call expressions.

* bpo-38530: When printing "NameError" raised by the interpreter,
  "PyErr_Display()" will offer suggestions of similar variable names
  in the function that the exception was raised from. Patch by Pablo
  Galindo

* bpo-43823: Improve syntax errors for invalid dictionary literals.
  Patch by Pablo Galindo.

* bpo-43822: Improve syntax errors in the parser for missing commas
  between expressions. Patch by Pablo Galindo.

* bpo-43798: "ast.alias" nodes now include source location metadata
  attributes e.g. lineno, col_offset.

* bpo-43797: Improve "SyntaxError" error messages for invalid
  comparisons. Patch by Pablo Galindo.

* bpo-43760: Move the flag for checking whether tracing is enabled to
  the C stack, from the heap. Should speed up dispatch in the
  interpreter.

* bpo-43682: Static methods ("@staticmethod") and class methods
  ("@classmethod") now inherit the method attributes ("__module__",
  "__name__", "__qualname__", "__doc__", "__annotations__") and have a
  new "__wrapped__" attribute. Patch by Victor Stinner.

* bpo-43751: Fixed a bug where "anext(ait, default)" would erroneously
  return None.

* bpo-42128: "__match_args__" is no longer allowed to be a list.

* bpo-43683: Add GEN_START opcode. Marks start of generator, including
  async, or coroutine and handles sending values to a newly created
  generator or coroutine.

* bpo-43105: Importlib now resolves relative paths when creating
  module spec objects from file locations.

* bpo-43682: Static methods ("@staticmethod") are now callable as
  regular functions. Patch by Victor Stinner.

* bpo-42609: Prevented crashes in the AST validator and optimizer when
  compiling some absurdly long expressions like ""+0"*1000000".
  "RecursionError" is now raised instead.

* bpo-38530: When printing "AttributeError", "PyErr_Display()" will
  offer suggestions of similar attribute names in the object that the
  exception was raised from. Patch by Pablo Galindo


Library
-------

* bpo-44015: In @dataclass(), raise a TypeError if KW_ONLY is
  specified more than once.

* bpo-25478: Added a *total()* method to collections.Counter() to
  compute the sum of the counts.

* bpo-43733: Change "netrc.netrc" to use UTF-8 encoding before using
  locale encoding.

* bpo-43979: Removed an unnecessary list comprehension before looping
  from "urllib.parse.parse_qsl()".  Patch by Christoph Zwerschke and
  Dong-hee Na.

* bpo-43993: Update bundled pip to 21.1.1.

* bpo-43957: [Enum] Deprecate "TypeError" when non-member is used in a
  containment check; In 3.12 "True" or "False" will be returned
  instead, and containment will return "True" if the value is either a
  member of that enum or one of its members’ value.

* bpo-42904: For backwards compatibility with previous minor versions
  of Python, if "typing.get_type_hints()" receives no namespace
  dictionary arguments, "typing.get_type_hints()" will search through
  the global then local namespaces during evaluation of stringized
  type annotations (string forward references) inside a class.

* bpo-43945: [Enum] Deprecate non-standard mixin format() behavior: in
  3.12 the enum member, not the member’s value, will be used for
  format() calls.

* bpo-41139: Deprecate undocumented "cgi.log()" API.

* bpo-43937: Fixed the "turtle" module working with non-default root
  window.

* bpo-43930: Update bundled pip to 21.1 and setuptools to 56.0.0

* bpo-43907: Fix a bug in the pure-Python pickle implementation when
  using protocol 5, where bytearray instances that occur several time
  in the pickled object graph would incorrectly unpickle into repeated
  copies of the bytearray object.

* bpo-43926: In "importlib.metadata", provide a uniform interface to
  "Description", allow for any field to be encoded with multiline
  values, remove continuation lines from multiline values, and add a
  ".json" property for easy access to the PEP 566 JSON-compatible
  form. Sync with "importlib_metadata 4.0".

* bpo-43920: OpenSSL 3.0.0: "load_verify_locations()" now returns a
  consistent error message when cadata contains no valid certificate.

* bpo-43607: "urllib" can now convert Windows paths with "\\?\"
  prefixes into URL paths.

* bpo-43817: Add "inspect.get_annotations()", which safely computes
  the annotations defined on an object.  It works around the quirks of
  accessing the annotations from various types of objects, and makes
  very few assumptions about the object passed in.
  "inspect.get_annotations()" can also correctly un-stringize
  stringized annotations.

  "inspect.signature()", "inspect.from_callable()", and
  "inspect.from_function()" now call "inspect.get_annotations()" to
  retrieve annotations.  This means "inspect.signature()" and
  "inspect.from_callable()" can now un-stringize stringized
  annotations, too.

* bpo-43284: platform.win32_ver derives the windows version from
  sys.getwindowsversion().platform_version which in turn derives the
  version from kernel32.dll (which can be of a different version than
  Windows itself). Therefore change the platform.win32_ver to
  determine the version using the platform module’s _syscmd_ver
  private function to return an accurate version.

* bpo-42854: The "ssl" module now uses "SSL_read_ex" and
  "SSL_write_ex" internally. The functions support reading and writing
  of data larger than 2 GB. Writing zero-length data no longer fails
  with a protocol violation error.

* bpo-42333: Port "_ssl" extension module to multiphase
  initialization.

* bpo-43880: "ssl" now raises DeprecationWarning for OP_NO_SSL/TLS*
  options, old TLS versions, old protocols, and other features that
  have been deprecated since Python 3.6, 3.7, or OpenSSL 1.1.0.

* bpo-41559: **PEP 612** is now implemented purely in Python; builtin
  "types.GenericAlias" objects no longer include "typing.ParamSpec" in
  "__parameters__" (with the exception of "collections.abc.Callable"‘s
  "GenericAlias"). This means previously invalid uses of "ParamSpec"
  (such as "list[P]") which worked in earlier versions of Python 3.10
  alpha, will now raise "TypeError" during substitution.

* bpo-43867: The "multiprocessing" "Server" class now explicitly
  catches "SystemExit" and closes the client connection in this case.
  It happens when the "Server.serve_client()" method reaches the end
  of file (EOF).

* bpo-40443: Remove unused imports: pyclbr no longer uses copy, and
  typing no longer uses ast. Patch by Victor Stinner.

* bpo-43820: Remove an unneeded copy of the namespace passed to
  dataclasses.make_dataclass().

* bpo-43787: Add "__iter__()" method to "bz2.BZ2File",
  "gzip.GzipFile", and "lzma.LZMAFile". It makes iterating them about
  2x faster. Patch by Inada Naoki.

* bpo-43680: Deprecate io.OpenWrapper and _pyio.OpenWrapper: use
  io.open and _pyio.open instead. Until Python 3.9, _pyio.open was not
  a static method and builtins.open was set to OpenWrapper to not
  become a bound method when set to a class variable. _io.open is a
  built-in function whereas _pyio.open is a Python function. In Python
  3.10, _pyio.open() is now a static method, and builtins.open() is
  now io.open().

* bpo-43680: The Python "_pyio.open()" function becomes a static
  method to behave as "io.open()" built-in function: don’t become a
  bound method when stored as a class variable. It becomes possible
  since static methods are now callable in Python 3.10. Moreover,
  "_pyio.OpenWrapper()" becomes a simple alias to "_pyio.open()".
  Patch by Victor Stinner.

* bpo-41515: Fix "KeyError" raised in "typing.get_type_hints()" due to
  synthetic modules that don’t appear in "sys.modules".

* bpo-43776: When "subprocess.Popen" args are provided as a string or
  as "pathlib.Path", the Popen instance repr now shows the right
  thing.

* bpo-42248: [Enum] ensure exceptions raised in "_missing__" are
  released

* bpo-43744: fix issue with enum member name matching the start of a
  private variable name

* bpo-43772: Fixed the return value of "TypeVar.__ror__". Patch by
  Jelle Zijlstra.

* bpo-43764: Add match_args parameter to @dataclass decorator to allow
  suppression of __match_args__ generation.

* bpo-43799: OpenSSL 3.0.0: define "OPENSSL_API_COMPAT" 1.1.1 to
  suppress deprecation warnings. Python requires OpenSSL 1.1.1 APIs.

* bpo-43478: Mocks can no longer be used as the specs for other Mocks.
  As a result, an already-mocked object cannot have an attribute
  mocked using "autospec=True" or be the subject of a
  "create_autospec(...)" call. This can uncover bugs in tests since
  these Mock-derived Mocks will always pass certain tests (e.g.
  "isinstance()") and builtin assert functions (e.g.
  assert_called_once_with) will unconditionally pass.

* bpo-43794: Add "ssl.OP_IGNORE_UNEXPECTED_EOF" constants (OpenSSL
  3.0.0)

* bpo-43785: Improve "bz2.BZ2File" performance by removing the RLock
  from BZ2File. This makes BZ2File thread unsafe in the face of
  multiple simultaneous readers or writers, just like its equivalent
  classes in "gzip" and "lzma" have always been.  Patch by Inada
  Naoki.

* bpo-43789: OpenSSL 3.0.0: Don’t call the password callback function
  a second time when first call has signaled an error condition.

* bpo-43788: The header files for "ssl" error codes are now OpenSSL
  version-specific. Exceptions will now show correct reason and
  library codes. The "make_ssl_data.py" script has been rewritten to
  use OpenSSL’s text file with error codes.

* bpo-43766: Implement **PEP 647** in the "typing" module by adding
  "TypeGuard".

* bpo-25264: "os.path.realpath()" now accepts a *strict* keyword-only
  argument. When set to "True", "OSError" is raised if a path doesn’t
  exist or a symlink loop is encountered.

* bpo-43780: In "importlib.metadata", incorporate changes from
  importlib_metadata 3.10: Add mtime-based caching during distribution
  discovery. Flagged use of dict result from "entry_points()" as
  deprecated.

* gh-47383: The "P.args" and "P.kwargs" attributes of
  "typing.ParamSpec" are now instances of the new classes
  "typing.ParamSpecArgs" and "typing.ParamSpecKwargs", which enables a
  more useful "repr()". Patch by Jelle Zijlstra.

* bpo-43731: Add an "encoding" parameter "logging.fileConfig()".

* bpo-43712: Add "encoding" and "errors" parameters to
  "fileinput.input()" and "fileinput.FileInput".

* bpo-38659: A "simple_enum" decorator is added to the "enum" module
  to convert a normal class into an Enum. "test_simple_enum" added to
  test simple enums against a corresponding normal Enum.  Standard
  library modules updated to use "simple_enum".

* bpo-43764: Fix an issue where "__match_args__" generation could fail
  for some "dataclasses".

* bpo-43752: Fix "sqlite3" regression for zero-sized blobs with
  converters, where "b""" was returned instead of "None". The
  regression was introduced by PR 24723. Patch by Erlend E. Aasland.

* bpo-43655: "tkinter" dialog windows are now recognized as dialogs by
  window managers on macOS and X Window.

* bpo-43723: The following "threading" methods are now deprecated and
  should be replaced:

  * "currentThread" => "threading.current_thread()"

  * "activeCount" => "threading.active_count()"

  * "Condition.notifyAll" => "threading.Condition.notify_all()"

  * "Event.isSet" => "threading.Event.is_set()"

  * "Thread.setName" => "threading.Thread.name"

  * "thread.getName" => "threading.Thread.name"

  * "Thread.isDaemon" => "threading.Thread.daemon"

  * "Thread.setDaemon" => "threading.Thread.daemon"

  Patch by Jelle Zijlstra.

* bpo-2135: Deprecate find_module() and find_loader() implementations
  in importlib and zipimport.

* bpo-43534: "turtle.textinput()" and "turtle.numinput()" create now a
  transient window working on behalf of the canvas window.

* bpo-43532: Add the ability to specify keyword-only fields to
  dataclasses. These fields will become keyword-only arguments to the
  generated __init__.

* bpo-43522: Fix problem with "hostname_checks_common_name". OpenSSL
  does not copy hostflags from *struct SSL_CTX* to *struct SSL*.

* bpo-8978: Improve error message for "tarfile.open()" when "lzma" /
  "bz2" are unavailable.  Patch by Anthony Sottile.

* bpo-42967: Allow "bytes" "separator" argument in
  "urllib.parse.parse_qs" and "urllib.parse.parse_qsl" when parsing
  "str" query strings. Previously, this raised a "TypeError".

* bpo-43296: Improve "sqlite3" error handling: "sqlite3_value_blob()"
  errors that set "SQLITE_NOMEM" now raise "MemoryError". Patch by
  Erlend E. Aasland.

* bpo-43312: New functions "sysconfig.get_preferred_scheme()" and
  "sysconfig.get_default_scheme()" are added to query a platform for
  its preferred “user”, “home”, and “prefix” (default) scheme names.

* bpo-43265: Improve "sqlite3.Connection.backup()" error handling. The
  error message for non-existent target database names is now "unknown
  database <database name>" instead of "SQL logic error". Patch by
  Erlend E. Aasland.

* bpo-41282: Install schemes in "distutils.command.install" are now
  loaded from "sysconfig".

* bpo-41282: "distutils.sysconfig" has been merged to "sysconfig".

* bpo-43176: Fixed processing of a dataclass that inherits from a
  frozen dataclass with no fields.  It is now correctly detected as an
  error.

* bpo-43080: "pprint" now has support for "dataclasses.dataclass".
  Patch by Lewis Gaul.

* bpo-39950: Add "pathlib.Path.hardlink_to()" method that supersedes
  "link_to()". The new method has the same argument order as
  "symlink_to()".

* bpo-42904: "typing.get_type_hints()" now checks the local namespace
  of a class when evaluating **PEP 563** annotations inside said
  class.

* bpo-42269: Add "slots" parameter to "dataclasses.dataclass"
  decorator to automatically generate "__slots__" for class. Patch
  provided by Yurii Karabas.

* bpo-39529: Deprecated use of "asyncio.get_event_loop()" without
  running event loop. Emit deprecation warning for "asyncio" functions
  which implicitly create a "Future" or "Task" objects if there is no
  running event loop and no explicit *loop* argument is passed:
  "ensure_future()", "wrap_future()", "gather()", "shield()",
  "as_completed()" and constructors of "Future", "Task",
  "StreamReader", "StreamReaderProtocol".

* bpo-18369: Certificate and PrivateKey classes were added to the ssl
  module. Certificates and keys can now be loaded from memory buffer,
  too.

* bpo-41486: Use a new output buffer management code for "bz2" /
  "lzma" / "zlib" modules, and add ".readall()" function to
  "_compression.DecompressReader" class. These bring some performance
  improvements. Patch by Ma Lin.

* bpo-31870: The "ssl.get_server_certificate()" function now has a
  *timeout* parameter.

* bpo-41735: Fix thread locks in zlib module may go wrong in rare
  case. Patch by Ma Lin.

* bpo-36470: Fix dataclasses with "InitVar"s and "replace()". Patch by
  Claudiu Popa.

* bpo-40849: Expose X509_V_FLAG_PARTIAL_CHAIN ssl flag

* bpo-35114: "ssl.RAND_status()" now returns a boolean value (as
  documented) instead of "1" or "0".

* bpo-39906: "pathlib.Path.stat()" and "chmod()" now accept a
  *follow_symlinks* keyword-only argument for consistency with
  corresponding functions in the "os" module.

* bpo-39899: "os.path.expanduser()" now refuses to guess Windows home
  directories if the basename of current user’s home directory does
  not match their username.

  "pathlib.Path.expanduser()" and "home()" now consistently raise
  "RuntimeError" exception when a home directory cannot be resolved.
  Previously a "KeyError" exception could be raised on Windows when
  the ""USERNAME""  environment variable was unset.

* bpo-36076: Added SNI support to "ssl.get_server_certificate()".

* bpo-38490: Covariance, Pearson’s correlation, and simple linear
  regression functionality was added to statistics module. Patch by
  Tymoteusz Wołodźko.

* bpo-33731: Provide a locale.localize() function, which converts a
  normalized number string into a locale format.

* bpo-32745: Fix a regression in the handling of ctypes’
  "ctypes.c_wchar_p" type: embedded null characters would cause a
  "ValueError" to be raised. Patch by Zackery Spytz.


Documentation
-------------

* bpo-43987: Add “Annotations Best Practices” document as a new HOWTO.

* bpo-43977: Document the new "Py_TPFLAGS_MAPPING" and
  "Py_TPFLAGS_SEQUENCE" type flags.

* bpo-43959: The documentation on the PyContextVar C-API was
  clarified.

* bpo-43938: Update dataclasses documentation to express that
  FrozenInstanceError is derived from AttributeError.

* bpo-43778: Fix the Sphinx glossary_search extension: create the
  _static/ sub-directory if it doesn’t exist.

* bpo-43755: Update documentation to reflect that unparenthesized
  lambda expressions can no longer be the expression part in an "if"
  clause in comprehensions and generator expressions since Python 3.9.

* bpo-43739: Fixing the example code in Doc/extending/extending.rst to
  declare and initialize the pmodule variable to be of the right type.


Tests
-----

* bpo-43961: Fix test_logging.test_namer_rotator_inheritance() on
  Windows: use "os.replace()" rather than "os.rename()". Patch by
  Victor Stinner.

* bpo-43842: Fix a race condition in the SMTP test of test_logging.
  Don’t close a file descriptor (socket) from a different thread while
  asyncore.loop() is polling the file descriptor. Patch by Victor
  Stinner.

* bpo-43843: "test.libregrtest" now marks a test as ENV_CHANGED
  (altered the execution environment) if a thread raises an exception
  but does not catch it. It sets a hook on "threading.excepthook()".
  Use "--fail-env-changed" option to mark the test as failed. Patch by
  Victor Stinner.

* bpo-43811: Tests multiple OpenSSL versions on GitHub Actions. Use
  ccache to speed up testing.

* bpo-43791: OpenSSL 3.0.0: Disable testing of legacy protocols TLS
  1.0 and 1.1. Tests are failing with TLSV1_ALERT_INTERNAL_ERROR.


Build
-----

* bpo-43567: Improved generated code refresh
  (AST/tokens/opcodes/keywords) on Windows.

* bpo-43669: Implement **PEP 644**. Python now requires OpenSSL 1.1.1
  or newer.


Windows
-------

* bpo-35306: Adds additional arguments to "os.startfile()" function.

* bpo-43538: Avoid raising errors from "pathlib.Path.exists()" when
  passed an invalid filename.

* bpo-38822: Fixed "os.stat()" failing on inaccessible directories
  with a trailing slash, rather than falling back to the parent
  directory’s metadata. This implicitly affected "os.path.exists()"
  and "os.path.isdir()".

* bpo-26227: Fixed decoding of host names in "socket.gethostbyaddr()"
  and "socket.gethostbyname_ex()".

* bpo-40432: Updated pegen regeneration script on Windows to find and
  use Python 3.8 or higher.  Prior to this, pegen regeneration already
  required 3.8 or higher, but the script may have used lower versions
  of Python.

* bpo-43745: Actually updates Windows release to OpenSSL 1.1.1k.
  Earlier releases were mislabelled and actually included 1.1.1i
  again.

* bpo-43652: Update Tcl and Tk to 8.6.11 in Windows installer.

* bpo-43492: Upgrade Windows installer to use SQLite 3.35.5.

* bpo-30555: Fix "WindowsConsoleIO" errors in the presence of fd
  redirection. Patch by Segev Finer.


macOS
-----

* bpo-42119: Fix check for macOS SDK paths when building Python.
  Narrow search to match contents of SDKs, namely only files in
  "/System/Library", "/System/IOSSupport", and "/usr" other than
  "/usr/local". Previously, anything under "/System" was assumed to be
  in an SDK which causes problems with the new file system layout in
  10.15+ where user file systems may appear to be mounted under
  "/System".  Paths in "/Library" were also incorrectly treated as SDK
  locations.

* bpo-43568: Drop support for MACOSX_DEPLOYMENT_TARGET < 10.3

* bpo-44009: Provide “python3.x-intel64” executable to allow reliably
  forcing macOS universal2 framework builds to run under Rosetta 2
  Intel-64 emulation on Apple Silicon Macs.  This can be useful for
  testing or when universal2 wheels are not yet available.

* bpo-43851: Build SQLite with "SQLITE_OMIT_AUTOINIT" on macOS. Patch
  by Erlend E. Aasland.

* bpo-43492: Update macOS installer to use SQLite 3.35.4.

* bpo-42235: "Mac/BuildScript/build-installer.py" will now use
  “–enable-optimizations” and "--with-lto" when building on macOS
  10.15 or later.


IDLE
----

* bpo-37903: Add mouse actions to the shell sidebar.  Left click and
  optional drag selects one or more lines, as with the editor line
  number sidebar.  Right click after selecting raises a context menu
  with ‘copy with prompts’.  This zips together prompts from the
  sidebar with lines from the selected text.

* bpo-43981: Fix reference leak in test_sidebar and test_squeezer.
  Patches by Terry Jan Reedy and Pablo Galindo

* bpo-37892: Indent IDLE Shell input with spaces instead of tabs

* bpo-43655: IDLE dialog windows are now recognized as dialogs by
  window managers on macOS and X Window.

* bpo-37903: IDLE’s shell now shows prompts in a separate side-bar.


C API
-----

* bpo-43916: Add a new "Py_TPFLAGS_DISALLOW_INSTANTIATION" type flag
  to disallow creating type instances. Patch by Victor Stinner.

* bpo-43774: Remove the now unused "PYMALLOC_DEBUG" macro. Debug hooks
  on memory allocators are now installed by default if Python is built
  in debug mode (if "Py_DEBUG" macro is defined). Moreover, they can
  now be used on Python build in release mode (ex: using
  "PYTHONMALLOC=debug" environment variable).

* bpo-43962: _PyInterpreterState_IDIncref() now calls
  _PyInterpreterState_IDInitref() and always increments id_refcount.
  Previously, calling _xxsubinterpreters.get_current() could create an
  id_refcount inconsistency when a _xxsubinterpreters.InterpreterID
  object was deallocated. Patch by Victor Stinner.

* bpo-28254: Add new C-API functions to control the state of the
  garbage collector: "PyGC_Enable()", "PyGC_Disable()",
  "PyGC_IsEnabled()", corresponding to the functions in the "gc"
  module.

* bpo-43908: Introduce "Py_TPFLAGS_IMMUTABLETYPE" flag for immutable
  type objects, and modify "PyType_Ready()" to set it for static
  types. Patch by Erlend E. Aasland.

* bpo-43795: "PyMem_Calloc()" is now available in the limited C API
  ("Py_LIMITED_API").

* bpo-43868: "PyOS_ReadlineFunctionPointer()" is no longer exported by
  limited C API headers and by "python3.dll" on Windows. Like any
  function that takes "FILE*", it is not part of the stable ABI.

* bpo-43795: Stable ABI and limited API definitions are generated from
  a central manifest (**PEP 652**).

* bpo-43753: Add the "Py_Is(x, y)" function to test if the *x* object
  is the *y* object, the same as "x is y" in Python. Add also the
  "Py_IsNone()", "Py_IsTrue()", "Py_IsFalse()" functions to test if an
  object is, respectively, the "None" singleton, the "True" singleton
  or the "False" singleton. Patch by Victor Stinner.


Python 3.10.0 alpha 7
=====================

*Release date: 2021-04-05*


Security
--------

* bpo-42988: CVE-2021-3426: Remove the "getfile" feature of the
  "pydoc" module which could be abused to read arbitrary files on the
  disk (directory traversal vulnerability). Moreover, even source code
  of Python modules can contain sensitive data like passwords.
  Vulnerability reported by David Schwörer.

* bpo-43285: "ftplib" no longer trusts the IP address value returned
  from the server in response to the PASV command by default.  This
  prevents a malicious FTP server from using the response to probe
  IPv4 address and port combinations on the client network.

  Code that requires the former vulnerable behavior may set a
  "trust_server_pasv_ipv4_address" attribute on their "ftplib.FTP"
  instances to "True" to re-enable it.

* bpo-43439: Add audit hooks for "gc.get_objects()",
  "gc.get_referrers()" and "gc.get_referents()". Patch by Pablo
  Galindo.


Core and Builtins
-----------------

* bpo-27129: Update CPython bytecode magic number.

* bpo-43672: Raise ImportWarning when calling find_loader().

* bpo-43660: Fix crash that happens when replacing "sys.stderr" with a
  callable that can remove the object while an exception is being
  printed. Patch by Pablo Galindo.

* bpo-27129: The bytecode interpreter uses instruction, rather byte,
  offsets internally. This reduces the number of EXTENDED_ARG
  instructions needed and streamlines instruction dispatch a bit.

* bpo-40645: Fix reference leak in the "_hashopenssl" extension. Patch
  by Pablo Galindo.

* bpo-42134: Calls to find_module() by the import system now raise
  ImportWarning.

* bpo-41064: Improve the syntax error for invalid usage of double
  starred elements (‘**’) in f-strings. Patch by Pablo Galindo.

* bpo-43575: Speed up calls to "map()" by using the **PEP 590**
  "vectorcall" calling convention. Patch by Dong-hee Na.

* bpo-42137: The import system now prefers using "__spec__" for
  "ModuleType.__repr__" over "module_repr()".

* bpo-43452: Added micro-optimizations to "_PyType_Lookup()" to
  improve cache lookup performance in the common case of cache hits.

* bpo-43555: Report the column offset for "SyntaxError" for invalid
  line continuation characters. Patch by Pablo Galindo.

* bpo-43517: Fix misdetection of circular imports when using "from
  pkg.mod import attr", which caused false positives in non-trivial
  multi-threaded code.

* bpo-43497: Emit SyntaxWarnings for assertions with tuple constants,
  this is a regression introduced in python3.7

* bpo-39316: Tracing now has correct line numbers for attribute
  accesses when the the attribute is on a different line from the
  object. Improves debugging and profiling for multi-line method
  chains.

* bpo-35883: Python no longer fails at startup with a fatal error if a
  command line argument contains an invalid Unicode character. The
  "Py_DecodeLocale()" function now escapes byte sequences which would
  be decoded as Unicode characters outside the [U+0000; U+10ffff]
  range.

* bpo-43410: Fix a bug that was causing the parser to crash when
  emitting syntax errors when reading input from stdin. Patch by Pablo
  Galindo

* bpo-43406: Fix a possible race condition where "PyErr_CheckSignals"
  tries to execute a non-Python signal handler.

* bpo-42128: Add "__match_args__" to "structsequence" based classes.
  Patch by Pablo Galindo.

* bpo-43390: CPython now sets the "SA_ONSTACK" flag in "PyOS_setsig"
  for the VM’s default signal handlers.  This is friendlier to other
  in-process code that an extension module or embedding use could pull
  in (such as Golang’s cgo) where tiny thread stacks are the norm and
  "sigaltstack()" has been used to provide for signal handlers.  This
  is a no-op change for the vast majority of processes that don’t use
  sigaltstack.

* bpo-43287: Speed up calls to "filter()" by using the **PEP 590**
  "vectorcall" calling convention. Patch by Dong-hee Na.

* bpo-37448: Add a radix tree based memory map to track in-use
  obmalloc arenas. Use to replace the old implementation of
  address_in_range(). The radix tree approach makes it easy to
  increase pool sizes beyond the OS page size. Boosting the pool and
  arena size allows obmalloc to handle a significantly higher
  percentage of requests from its ultra-fast paths.

  It also has the advantage of eliminating the memory unsanitary
  behavior of the previous address_in_range(). The old
  address_in_range() was marked with the annotations
  _Py_NO_SANITIZE_ADDRESS, _Py_NO_SANITIZE_THREAD, and
  _Py_NO_SANITIZE_MEMORY. Those annotations are no longer needed.

  To disable the radix tree map, set a preprocessor flag as follows:
  "-DWITH_PYMALLOC_RADIX_TREE=0".

  Co-authored-by: Tim Peters <tim.peters@gmail.com>

* bpo-29988: Only handle asynchronous exceptions and requests to drop
  the GIL when returning from a call or on the back edges of loops.
  Makes sure that "__exit__()" is always called in with statements,
  even for interrupts.


Library
-------

* bpo-43720: Document various stdlib deprecations in imp, pkgutil, and
  importlib.util for removal in Python 3.12.

* bpo-43433: "xmlrpc.client.ServerProxy" no longer ignores query and
  fragment in the URL of the server.

* bpo-31956: The "index()" method of "array.array" now has optional
  *start* and *stop* parameters.

* bpo-40066: Enum: adjust "repr()" to show only enum and member name
  (not value, nor angle brackets) and "str()" to show only member
  name.  Update and improve documentation to match.

* bpo-42136: Deprecate all module_repr() methods found in importlib as
  their use is being phased out by Python 3.12.

* bpo-35930: Raising an exception raised in a “future” instance will
  create reference cycles.

* bpo-41369: Finish updating the vendored libmpdec to version 2.5.1.
  Patch by Stefan Krah.

* bpo-43422: Revert the _decimal C API which was added in bpo-41324.

* bpo-43577: Fix deadlock when using "ssl.SSLContext" debug callback
  with "ssl.SSLContext.sni_callback()".

* bpo-43571: It’s now possible to create MPTCP sockets with
  IPPROTO_MPTCP

* bpo-43542: "image/heic" and "image/heif" were added to "mimetypes".

* bpo-40645: The "hmac" module now uses OpenSSL’s HMAC implementation
  when digestmod argument is a hash name or builtin hash function.

* bpo-43510: Implement **PEP 597**: Add "EncodingWarning" warning, "-X
  warn_default_encoding" option, "PYTHONWARNDEFAULTENCODING"
  environment variable and "encoding="locale"" argument value.

* bpo-43521: "ast.unparse" can now render NaNs and empty sets.

* bpo-42914: "pprint.pprint()" gains a new boolean
  "underscore_numbers" optional argument to emit integers with
  thousands separated by an underscore character for improved
  readability (for example "1_000_000" instead of "1000000").

* bpo-41361: "rotate()" calls are now slightly faster due to faster
  argument parsing.

* bpo-43423: "subprocess.communicate()" no longer raises an IndexError
  when there is an empty stdout or stderr IO buffer during a timeout
  on Windows.

* bpo-27820: Fixed long-standing bug of smtplib.SMTP where doing AUTH
  LOGIN with initial_response_ok=False will fail.

  The cause is that SMTP.auth_login _always_ returns a password if
  provided with a challenge string, thus non-compliant with the
  standard for AUTH LOGIN.

  Also fixes bug with the test for smtpd.

* bpo-43445: Add frozen modules to "sys.stdlib_module_names". For
  example, add ""_frozen_importlib"" and
  ""_frozen_importlib_external"" names.

* bpo-43245: Add keyword arguments support to "ChainMap.new_child()".

* bpo-29982: Add optional parameter *ignore_cleanup_errors* to
  "tempfile.TemporaryDirectory()" and allow multiple "cleanup()"
  attempts. Contributed by C.A.M. Gerlach.

* bpo-43428: Include changes from importlib_metadata 3.7:

  Performance enhancements to distribution discovery.

  "entry_points" only returns unique distributions.

  Introduces new "EntryPoints" object for containing a set of entry
  points with convenience methods for selecting entry points by group
  or name. "entry_points" now returns this object if selection
  parameters are supplied but continues to return a dict object for
  compatibility. Users are encouraged to rely on the selection
  interface. The dict object result is likely to be deprecated in the
  future.

  Added packages_distributions function to return a mapping of
  packages to the distributions that provide them.

* bpo-43332: Improves the networking efficiency of "http.client" when
  using a proxy via "set_tunnel()".  Fewer small send calls are made
  during connection setup.

* bpo-43420: Improve performance of "fractions.Fraction" arithmetics
  for large components.  Contributed by Sergey B. Kirpichev.

* bpo-43356: Allow passing a signal number to
  "_thread.interrupt_main()".

* bpo-43399: Fix "ElementTree.extend" not working on iterators when
  using the Python implementation

* bpo-43369: Improve "sqlite3" error handling: If
  "sqlite3_column_text()" and "sqlite3_column_blob()" set
  "SQLITE_NOMEM", "MemoryError" is now raised. Patch by Erlend E.
  Aasland.

* bpo-43368: Fix a regression introduced in PR 24562, where an empty
  bytestring was fetched as "None" instead of "b''" in "sqlite3".
  Patch by Mariusz Felisiak.

* bpo-41282: Fixed stacklevel of "DeprecationWarning" emitted from
  "import distutils".

* bpo-42129: "importlib.resources" now honors namespace packages,
  merging resources from each location in the namespace as introduced
  in "importlib_resources" 3.2 and including incidental changes
  through 5.0.3.

* bpo-43295: "datetime.datetime.strptime()" now raises "ValueError"
  instead of "IndexError" when matching "'z'" with the "%z" format
  specifier.

* bpo-43125: Return empty string if base64mime.body_encode receive
  empty bytes

* bpo-43084: "curses.window.enclose()" returns now "True" or "False"
  (as was documented) instead of "1" or "0".

* bpo-42994: Add MIME types for opus, AAC, 3gpp and 3gpp2

* bpo-14678: Add an invalidate_caches() method to the
  zipimport.zipimporter class to support
  importlib.invalidate_caches(). Patch by Desmond Cheong.

* bpo-42782: Fail fast in "shutil.move()" to avoid creating
  destination directories on failure.

* bpo-40066: Enum’s "repr()" and "str()" have changed: "repr()" is now
  *EnumClass.MemberName* and "str()" is *MemberName*.  Additionally,
  stdlib Enum’s whose contents are available as module attributes,
  such as "RegexFlag.IGNORECASE", have their "repr()" as
  *module.name*, e.g. "re.IGNORECASE".

* bpo-26053: Fixed bug where the "pdb" interactive run command echoed
  the args from the shell command line, even if those have been
  overridden at the pdb prompt.

* bpo-24160: Fixed bug where breakpoints did not persist across
  multiple debugger sessions in "pdb"’s interactive mode.

* bpo-40701: When the "tempfile.tempdir" global variable is set to a
  value of type bytes, it is now handled consistently.  Previously
  exceptions could be raised from some tempfile APIs when the
  directory did not already exist in this situation.  Also ensures
  that the "tempfile.gettempdir()" and "tempfile.gettempdirb()"
  functions *always* return "str" and "bytes" respectively.

* bpo-39342: Expose "X509_V_FLAG_ALLOW_PROXY_CERTS" as
  "VERIFY_ALLOW_PROXY_CERTS" to allow proxy certificate validation as
  explained in https://www.openssl.org/docs/man1.1.1/man7/proxy-
  certificates.html.

* bpo-31861: Add builtins.aiter and builtins.anext. Patch by Joshua
  Bronson (@jab), Daniel Pope (@lordmauve), and Justin Wang
  (@justin39).


Documentation
-------------

* bpo-43199: Answer “Why is there no goto?” in the Design and History
  FAQ.

* bpo-43407: Clarified that a result from "time.monotonic()",
  "time.perf_counter()", "time.process_time()", or
  "time.thread_time()" can be compared with the result from any
  following call to the same function - not just the next immediate
  call.

* bpo-43354: Fix type documentation for "Fault.faultCode"; the type
  has to be "int" instead of "str".

* bpo-41933: Clarified wording of s * n in the Common Sequence
  Operations


Tests
-----

* bpo-37945: Fix test_getsetlocale_issue1813() of test_locale: skip
  the test if "setlocale()" fails. Patch by Victor Stinner.

* bpo-41561: Add workaround for Ubuntu’s custom OpenSSL security level
  policy.


Build
-----

* bpo-43179: Introduce and correctly use ALIGNOF_X in place of
  SIZEOF_X for alignment-related code in optimized string routines.
  Patch by Jessica Clarke.

* bpo-43631: Update macOS, Windows, and CI to OpenSSL 1.1.1k.

* bpo-43617: Improve configure.ac: Check for presence of autoconf-
  archive package and remove our copies of M4 macros.

* bpo-43466: The "configure" script now supports "--with-openssl-
  rpath" option.

* bpo-43372: Use "_freeze_importlib" to generate code for the
  "__hello__" module. This approach ensures the code matches the
  interpreter version.  Previously, PYTHON_FOR_REGEN was used to
  generate the code, which might be wrong.  The marshal format for
  code objects has changed with bpo-42246, commit 877df851. Update the
  code and the expected code sizes in ctypes test_frozentable.


Windows
-------

* bpo-43440: Build "sqlite3" with the "R*Tree" module enabled. Patch
  by Erlend E. Aasland.


IDLE
----

* bpo-42225: Document that IDLE can fail on Unix either from
  misconfigured IP masquerade rules or failure displaying complex
  colored (non-ascii) characters.


C API
-----

* bpo-43688: The limited C API is now supported if Python is built in
  debug mode (if the "Py_DEBUG" macro is defined). In the limited C
  API, the "Py_INCREF()" and "Py_DECREF()" functions are now
  implemented as opaque function calls, rather than accessing directly
  the "PyObject.ob_refcnt" member, if Python is built in debug mode
  and the "Py_LIMITED_API" macro targets Python 3.10 or newer. It
  became possible to support the limited C API in debug mode because
  the "PyObject" structure is the same in release and debug mode since
  Python 3.8 (see bpo-36465).

  The limited C API is still not supported in the "--with-trace-refs"
  special build ("Py_TRACE_REFS" macro).

  Patch by Victor Stinner.

* bpo-43244: Remove the "pyarena.h" header file with functions:

  * "PyArena_New()"

  * "PyArena_Free()"

  * "PyArena_Malloc()"

  * "PyArena_AddPyObject()"

  These functions were undocumented, excluded from the limited C API,
  and were only used internally by the compiler. Patch by Victor
  Stinner.

* bpo-43244: Remove the compiler and parser functions using "struct
  _mod" type, because the public AST C API was removed:

  * "PyAST_Compile()"

  * "PyAST_CompileEx()"

  * "PyAST_CompileObject()"

  * "PyFuture_FromAST()"

  * "PyFuture_FromASTObject()"

  * "PyParser_ASTFromFile()"

  * "PyParser_ASTFromFileObject()"

  * "PyParser_ASTFromFilename()"

  * "PyParser_ASTFromString()"

  * "PyParser_ASTFromStringObject()"

  These functions were undocumented and excluded from the limited C
  API. Patch by Victor Stinner.

* bpo-43244: Remove "ast.h", "asdl.h", and "Python-ast.h" header
  files. These functions were undocumented and excluded from the
  limited C API. Most names defined by these header files were not
  prefixed by "Py" and so could create names conflicts. For example,
  "Python-ast.h" defined a "Yield" macro which was conflict with the
  "Yield" name used by the Windows "<winbase.h>" header. Use the
  Python "ast" module instead. Patch by Victor Stinner.

* bpo-43541: Fix a "PyEval_EvalCodeEx()" regression: fix reference
  counting on builtins. Patch by Victor Stinner.

* bpo-43244: Remove the "symtable.h" header file and the undocumented
  functions:

  * "PyST_GetScope()"

  * "PySymtable_Build()"

  * "PySymtable_BuildObject()"

  * "PySymtable_Free()"

  * "Py_SymtableString()"

  * "Py_SymtableStringObject()"

  The "Py_SymtableString()" function was part the stable ABI by
  mistake but it could not be used, because the "symtable.h" header
  file was excluded from the limited C API.

  The Python "symtable" module remains available and is unchanged.

  Patch by Victor Stinner.

* bpo-43244: Remove the "PyAST_Validate()" function. It is no longer
  possible to build a AST object ("mod_ty" type) with the public C
  API. The function was already excluded from the limited C API (**PEP
  384**). Patch by Victor Stinner.


Python 3.10.0 alpha 6
=====================

*Release date: 2021-03-01*


Security
--------

* bpo-42967: Fix web cache poisoning vulnerability by defaulting the
  query args separator to "&", and allowing the user to choose a
  custom separator.


Core and Builtins
-----------------

* bpo-43321: Fix "SystemError" raised when "PyArg_Parse*()" is used
  with "#" but without "PY_SSIZE_T_CLEAN" defined.

* bpo-36346: "PyArg_Parse*()" functions now emits "DeprecationWarning"
  when "u" or "Z" format is used. See **PEP 623** for detail.

* bpo-43277: Add a new "PySet_CheckExact()" function to the C-API to
  check if an object is an instance of "set" but not an instance of a
  subtype. Patch by Pablo Galindo.

* bpo-42990: The "types.FunctionType" constructor now inherits the
  current builtins if the *globals* dictionary has no ""__builtins__""
  key, rather than using "{"None": None}" as builtins: same behavior
  as "eval()" and "exec()" functions. Defining a function with "def
  function(...): ..." in Python is not affected, globals cannot be
  overridden with this syntax: it also inherits the current builtins.
  Patch by Victor Stinner.

* bpo-42990: Functions have a new "__builtins__" attribute which is
  used to look for builtin symbols when a function is executed,
  instead of looking into "__globals__['__builtins__']". Patch by Mark
  Shannon and Victor Stinner.

* bpo-43149: Improve the error message in the parser for exception
  groups without parentheses. Patch by Pablo Galindo.

* bpo-43121: Fixed an incorrect "SyntaxError" message for missing
  comma in literals. Patch by Pablo Galindo.

* bpo-42819: "readline": Explicitly disable bracketed paste in the
  interactive interpreter, even if it’s set in the inputrc, is enabled
  by default (eg GNU Readline 8.1), or a user calls
  "readline.read_init_file()". The Python REPL has not implemented
  bracketed paste support. Also, bracketed mode writes the
  ""\x1b[?2004h"" escape sequence into stdout which causes test
  failures in applications that don’t support it. It can still be
  explicitly enabled by calling "readline.parse_and_bind("set enable-
  bracketed-paste on")". Patch by Dustin Rodrigues.

* bpo-42808: Simple calls to "type(object)" are now faster due to the
  "vectorcall" calling convention. Patch by Dennis Sweeney.

* bpo-42217: Make the compiler merges same co_code and co_linetable
  objects in a module like already did for co_consts.

* bpo-41972: Substring search functions such as "str1 in str2" and
  "str2.find(str1)" now sometimes use the “Two-Way” string comparison
  algorithm to avoid quadratic behavior on long strings.

* bpo-42128: Implement **PEP 634** (structural pattern matching).
  Patch by Brandt Bucher.

* bpo-40692: In the "concurrent.futures.ProcessPoolExecutor", validate
  that "multiprocess.synchronize()" is available on a given platform
  and rely on that check in the "concurrent.futures" test suite so we
  can run tests that are unrelated to "ProcessPoolExecutor" on those
  platforms.

* bpo-38302: If "object.__ipow__()" returns "NotImplemented", the
  operator will correctly fall back to "object.__pow__()" and
  "object.__rpow__()" as expected.


Library
-------

* bpo-43316: The "python -m gzip" command line application now
  properly fails when detecting an unsupported extension. It exits
  with a non-zero exit code and prints an error message to stderr.

* bpo-43317: Set the chunk size for the "gzip" module main function to
  io.DEFAULT_BUFFER_SIZE. This is slightly faster than the 1024 bytes
  constant that was used previously.

* bpo-43146: Handle None in single-arg versions of "print_exception()"
  and "format_exception()".

* bpo-43260: Fix TextIOWrapper can not flush internal buffer forever
  after very large text is written.

* bpo-43258: Prevent needless allocation of "sqlite3" aggregate
  function context when no rows match an aggregate query. Patch by
  Erlend E. Aasland.

* bpo-43251: Improve "sqlite3" error handling: "sqlite3_column_name()"
  failures now result in "MemoryError". Patch by Erlend E. Aasland.

* bpo-40956: Fix segfault in "sqlite3.Connection.backup()" if no
  argument was provided. The regression was introduced by PR 23838.
  Patch by Erlend E. Aasland.

* bpo-43172: The readline module now passes its tests when built
  directly against libedit. Existing irreconcilable API differences
  remain in "readline.get_begidx()" and "readline.get_endidx()"
  behavior based on libreadline vs libedit use.

* bpo-43163: Fix a bug in "codeop" that was causing it to not ask for
  more input when multi-line snippets have unclosed parentheses. Patch
  by Pablo Galindo

* bpo-43162: deprecate unsupported ability to access enum members as
  attributes of other enum members

* bpo-43146: Fix recent regression in None argument handling in
  "traceback" module functions.

* bpo-43102: The namedtuple __new__ method had its __builtins__ set to
  None instead of an actual dictionary.  This created problems for
  introspection tools.

* bpo-43106: Added "O_EVTONLY", "O_FSYNC", "O_SYMLINK" and
  "O_NOFOLLOW_ANY" for macOS. Patch by Dong-hee Na.

* bpo-42960: Adds "resource.RLIMIT_KQUEUES" constant from FreeBSD to
  the "resource" module.

* bpo-42151: Make the pure Python implementation of
  "xml.etree.ElementTree" behave the same as the C implementation
  ("_elementree") regarding default attribute values (by not setting
  "specified_attributes=1").

* bpo-29753: In ctypes, now packed bitfields are calculated properly
  and the first item of packed bitfields is now shrank correctly.


Documentation
-------------

* bpo-27646: Clarify that ‘yield from <expr>’ works with any iterable,
  not just iterators.

* bpo-36346: Update some deprecated unicode APIs which are documented
  as “will be removed in 4.0” to “3.12”. See **PEP 623** for detail.


Tests
-----

* bpo-43288: Fix test_importlib to correctly skip Unicode file tests
  if the filesystem does not support them.


Build
-----

* bpo-43174: Windows build now uses "/utf-8" compiler option.

* bpo-43103: Add a new configure "--without-static-libpython" option
  to not build the "libpythonMAJOR.MINOR.a" static library and not
  install the "python.o" object file.

* bpo-13501: The configure script can now use *libedit* instead of
  *readline* with the command line option "--with-readline=editline".

* bpo-42603: Make configure script use pkg-config to detect the
  location of Tcl/Tk headers and libraries, used to build tkinter.

  On macOS, a Tcl/Tk configuration provided by pkg-config will be
  preferred over Tcl/Tk frameworks installed in
  "/{System/,}Library/Frameworks". If both exist and the latter is
  preferred, the appropriate "--with-tcltk-*" configuration options
  need to be explicitly set.

* bpo-39448: Add the “regen-frozen” makefile target that regenerates
  the code for the frozen "__hello__" module.


Windows
-------

* bpo-43155: "PyCMethod_New()" is now present in "python3.lib".


macOS
-----

* bpo-41837: Update macOS installer build to use OpenSSL 1.1.1j.


IDLE
----

* bpo-43283: Document why printing to IDLE’s Shell is often slower
  than printing to a system terminal and that it can be made faster by
  pre-formatting a single string before printing.


C API
-----

* bpo-43278: Always put compiler and system information on the first
  line of the REPL welcome message.

* bpo-43270: Remove the private "_PyErr_OCCURRED()" macro: use the
  public "PyErr_Occurred()" function instead.

* bpo-35134: Move odictobject.h, parser_interface.h,
  picklebufobject.h, pydebug.h, and pyfpe.h into the cpython/
  directory. They must not be included directly, as they are already
  included by Python.h: Include Files.

* bpo-35134: Move pyarena.h, pyctype.h, and pytime.h into the cpython/
  directory. They must not be included directly, as they are already
  included by Python.h: Include Files.

* bpo-40170: "PyExceptionClass_Name()" is now always declared as a
  function, in order to hide implementation details. The macro
  accessed "PyTypeObject.tp_name" directly.  Patch by Erlend E.
  Aasland.

* bpo-43239: The "PyCFunction_New()" function is now exported in the
  ABI when compiled with "-fvisibility=hidden".

* bpo-40170: "PyIter_Check()" is now always declared as a function, in
  order to hide implementation details. The macro accessed
  "PyTypeObject.tp_iternext" directly. Patch by Erlend E. Aasland.

* bpo-40170: Convert "PyDescr_IsData()" macro to a function to hide
  implementation details: The macro accessed
  "PyTypeObject.tp_descr_set" directly. Patch by Erlend E. Aasland.

* bpo-43181: Convert "PyObject_TypeCheck()" macro to a static inline
  function. Patch by Erlend E. Aasland.


Python 3.10.0 alpha 5
=====================

*Release date: 2021-02-02*


Security
--------

* bpo-42938: Avoid static buffers when computing the repr of
  "ctypes.c_double" and "ctypes.c_longdouble" values.


Core and Builtins
-----------------

* bpo-42990: Refactor the "PyEval_" family of functions.

  * An new function "_PyEval_Vector" is added to simplify calls to
    Python from C.

  * "_PyEval_EvalCodeWithName" is removed

  * "PyEval_EvalCodeEx" is retained as part of the API, but is not
    used internally

* bpo-38631: Replace "Py_FatalError()" calls in the compiler with
  regular "SystemError" exceptions. Patch by Victor Stinner.

* bpo-42997: Improve error message for missing “:” before blocks.
  Patch by Pablo Galindo.

* bpo-43017: Improve error message in the parser when using un-
  parenthesised tuples in comprehensions. Patch by Pablo Galindo.

* bpo-42986: Fix parser crash when reporting syntax errors in f-string
  with newlines. Patch by Pablo Galindo.

* bpo-40176: Syntax errors for unterminated string literals now point
  to the start of the string instead of reporting EOF/EOL.

* bpo-42927: The inline cache for "LOAD_ATTR" now also optimizes
  access to attributes defined by "__slots__". This makes reading such
  attribute up to 30% faster.

* bpo-42864: Improve error messages in the parser when parentheses are
  not closed. Patch by Pablo Galindo.

* bpo-42924: Fix "bytearray" repetition incorrectly copying data from
  the start of the buffer, even if the data is offset within the
  buffer (e.g. after reassigning a slice at the start of the
  "bytearray" to a shorter byte string).

* bpo-42882: Fix the "_PyUnicode_FromId()" function
  (_Py_IDENTIFIER(var) API) when "Py_Initialize()" / "Py_Finalize()"
  is called multiple times: preserve
  "_PyRuntime.unicode_ids.next_index" value.

* bpo-42827: Fix a crash when working out the error line of a
  "SyntaxError" in some multi-line expressions.

* bpo-42823: frame.f_lineno is correct even if frame.f_trace is set to
  True

* bpo-37324: Remove deprecated aliases to Collections Abstract Base
  Classes from the "collections" module.

* bpo-41994: Fixed possible leak in "import" when "sys.modules" is not
  a "dict".

* bpo-27772: In string formatting, preceding the *width* field by
  "'0'" no longer affects the default alignment for strings.


Library
-------

* bpo-43108: Fixed a reference leak in the "curses" module. Patch by
  Pablo Galindo

* bpo-43077: Update the bundled pip to 21.0.1 and setuptools to
  52.0.0.

* bpo-41282: Deprecate "distutils" in documentation and add warning on
  import.

* bpo-43014: Improve performance of "tokenize" by 20-30%.  Patch by
  Anthony Sottile.

* bpo-42323: Fix "math.nextafter()" for NaN on AIX.

* bpo-42955: Add "sys.stdlib_module_names", containing the list of the
  standard library module names. Patch by Victor Stinner.

* bpo-42944: Fix "random.Random.sample" when "counts" argument is not
  "None".

* bpo-42934: Use "TracebackException"’s new "compact" param in
  "TestResult" to reduce time and memory consumed by traceback
  formatting.

* bpo-42931: Add "randbytes()" to "random.__all__".

* bpo-38250: [Enum] Flags consisting of a single bit are now
  considered canonical, and will be the only flags returned from
  listing and iterating over a Flag class or a Flag member.  Multi-bit
  flags are considered aliases; they will be returned from lookups and
  operations that result in their value. Iteration for both Flag and
  Flag members is in definition order.

* bpo-42877: Added the "compact" parameter to the constructor of
  "traceback.TracebackException" to reduce time and memory for use
  cases that only need to call "TracebackException.format()" and
  "TracebackException.format_exception_only()".

* bpo-42923: The "Py_FatalError()" function and the "faulthandler"
  module now dump the list of extension modules on a fatal error.

* bpo-42848: Removed recursion from "TracebackException" to allow it
  to handle long exception chains.

* bpo-42901: [Enum] move member creation from "EnumMeta.__new__" to
  "_proto_member.__set_name__", allowing members to be created and
  visible in "__init_subclass__".

* bpo-42780: Fix os.set_inheritable() for O_PATH file descriptors on
  Linux.

* bpo-42866: Fix a reference leak in the "getcodec()" function of CJK
  codecs. Patch by Victor Stinner.

* bpo-42846: Convert the 6 CJK codec extension modules (_codecs_cn,
  _codecs_hk, _codecs_iso2022, _codecs_jp, _codecs_kr and _codecs_tw)
  to the multiphase initialization API (**PEP 489**). Patch by Victor
  Stinner.

* bpo-42851: remove __init_subclass__ support for Enum members

* bpo-42834: Make internal caches of the "_json" module compatible
  with subinterpreters.

* bpo-41748: Fix HTMLParser parsing rules for element attributes
  containing commas with spaces. Patch by Karl Dubost.

* bpo-40810: Require SQLite 3.7.15 or newer. Patch by Erlend E.
  Aasland.

* bpo-1635741: Convert the _multibytecodec extension module (CJK
  codecs) to multi-phase initialization (**PEP 489**).  Patch by
  Erlend E. Aasland.

* bpo-42802: The distutils "bdist_wininst" command deprecated in
  Python 3.8 has been removed. The distutils "bdist_wheel" command is
  now recommended to distribute binary packages on Windows.

* bpo-24464: The undocumented built-in function
  "sqlite3.enable_shared_cache" is now deprecated, scheduled for
  removal in Python 3.12.  Its use is strongly discouraged by the
  SQLite3 documentation.  Patch by Erlend E. Aasland.

* bpo-42384: Make pdb populate sys.path[0] exactly the same as regular
  python execution.

* bpo-42383: Fix pdb: previously pdb would fail to restart the
  debugging target if it was specified using a relative path and the
  current directory changed.

* bpo-42005: Fix CLI of "cProfile" and "profile" to catch
  "BrokenPipeError".

* bpo-41604: Don’t decrement the reference count of the previous
  user_ptr when set_panel_userptr fails.

* bpo-41149: Allow executing callables that have a boolean value of
  "False" when passed to "Threading.thread" as the target. Patch
  contributed by Barney Stratford.

* bpo-38307: Add an ‘end_lineno’ attribute to the Class and Function
  objects that appear in the tree returned by pyclbr functions.  This
  and the existing ‘lineno’ attribute define the extent of class and
  def statements. Patch by Aviral Srivastava.

* bpo-39273: The "BUTTON5_*" constants are now exposed in the "curses"
  module if available.

* bpo-33289: Correct call to "tkinter.colorchooser" to return RGB
  triplet of ints instead of floats.  Patch by Cheryl Sabella.


Documentation
-------------

* bpo-40304: Fix doc for type(name, bases, dict).  Patch by Boris
  Verkhovskiy and Éric Araujo.

* bpo-42811: Updated importlib.utils.resolve_name() doc to use
  __spec__.parent instead of __package__. (Thanks Yair Frid.)


Tests
-----

* bpo-40823: Use "unittest.TestLoader().loadTestsFromTestCase()"
  instead of "unittest.makeSuite()" in "sqlite3" tests. Patch by
  Erlend E. Aasland.

* bpo-40810: In "sqlite3", fix "CheckTraceCallbackContent" for SQLite
  pre 3.7.15.


Build
-----

* bpo-43031: Pass "--timeout=$(TESTTIMEOUT)" option to the default
  profile task "./python -m test --pgo" command.

* bpo-36143: "make regen-all" now also runs "regen-keyword". Patch by
  Victor Stinner.

* bpo-42874: Removed the grep -q and -E flags in the tzpath validation
  section of the configure script to better accommodate users of some
  platforms (specifically Solaris 10).

* bpo-31904: Add library search path by wr-cc in
  add_cross_compiling_paths() for VxWorks.

* bpo-42856: Add "--with-wheel-pkg-dir=PATH" option to the
  "./configure" script. If specified, the "ensurepip" module looks for
  "setuptools" and "pip" wheel packages in this directory: if both are
  present, these wheel packages are used instead of ensurepip bundled
  wheel packages.

  Some Linux distribution packaging policies recommend against
  bundling dependencies. For example, Fedora installs wheel packages
  in the "/usr/share/python-wheels/" directory and don’t install the
  "ensurepip._bundled" package.


Windows
-------

* bpo-41837: Updated Windows installer to include OpenSSL 1.1.1i

* bpo-42584: Upgrade Windows installer to use SQLite 3.34.0.


macOS
-----

* bpo-42504: Ensure that the value of
  sysconfig.get_config_var(‘MACOSX_DEPLOYMENT_TARGET’) is always a
  string, even in when the value is parsable as an integer.


IDLE
----

* bpo-43008: Make IDLE invoke "sys.excepthook()" in normal, 2-process
  mode. Patch by Ken Hilton.

* bpo-33065: Fix problem debugging user classes with __repr__ method.

* bpo-23544: Disable Debug=>Stack Viewer when user code is running or
  Debugger is active, to prevent hang or crash.  Patch by Zackery
  Spytz.

* bpo-32631: Finish zzdummy example extension module: make menu
  entries work; add docstrings and tests with 100% coverage.


C API
-----

* bpo-42979: When Python is built in debug mode (with C assertions),
  calling a type slot like "sq_length" ("__len__()" in Python) now
  fails with a fatal error if the slot succeeded with an exception
  set, or failed with no exception set. The error message contains the
  slot, the type name, and the current exception (if an exception is
  set). Patch by Victor Stinner.

* bpo-43030: Fixed a compiler warning in "Py_UNICODE_ISSPACE()" on
  platforms with signed "wchar_t".


Python 3.10.0 alpha 4
=====================

*Release date: 2021-01-04*


Core and Builtins
-----------------

* bpo-42814: Fix undefined behavior in "Objects/genericaliasobject.c".

* bpo-42806: Fix the column offsets for f-strings "ast" nodes
  surrounded by parentheses and for nodes that spawn multiple lines.
  Patch by Pablo Galindo.

* bpo-40631: Fix regression where a single parenthesized starred
  expression was a valid assignment target.

* bpo-27794: Improve the error message for failed writes/deletes to
  property objects. When possible, the attribute name is now shown.
  Patch provided by Yurii Karabas.

* bpo-42745: Make the type attribute lookup cache per-interpreter.
  Patch by Victor Stinner.

* bpo-42246: Jumps to jumps are not eliminated when it would break PEP
  626.

* bpo-42246: Make sure that the "f_lasti" and "f_lineno" attributes of
  a frame are set correctly when an exception is raised or re-raised.
  Required for PEP 626.

* bpo-32381: The coding cookie (ex: "# coding: latin1") is now ignored
  in the command passed to the "-c" command line option. Patch by
  Victor Stinner.

* bpo-30858: Improve error location in expressions that contain
  assignments. Patch by Pablo Galindo and Lysandros Nikolaou.

* bpo-42615: Remove jump commands made redundant by the deletion of
  unreachable bytecode blocks

* bpo-42639: Make the "atexit" module state per-interpreter. It is now
  safe have more than one "atexit" module instance. Patch by Dong-hee
  Na and Victor Stinner.

* bpo-32381: Fix encoding name when running a ".pyc" file on Windows:
  "PyRun_SimpleFileExFlags()" now uses the correct encoding to decode
  the filename.

* bpo-42195: The "__args__" of the parameterized generics for
  "typing.Callable" and "collections.abc.Callable" are now consistent.
  The "__args__" for "collections.abc.Callable" are now flattened
  while "typing.Callable"’s have not changed.  To allow this change,
  "types.GenericAlias" can now be subclassed and
  "collections.abc.Callable"’s "__class_getitem__" will now return a
  subclass of "types.GenericAlias".  Tests for typing were also
  updated to not subclass things like "Callable[..., T]" as that is
  not a valid base class.  Finally, both "Callable"s no longer
  validate their "argtypes", in "Callable[[argtypes], resulttype]" to
  prepare for **PEP 612**.  Patch by Ken Jin.

* bpo-40137: Convert functools module to use
  "PyType_FromModuleAndSpec()".

* bpo-40077: Convert "array" to use heap types, and establish module
  state for these.

* bpo-42008: Fix _random.Random() seeding.

* bpo-1635741: Port the "pyexpat" extension module to multi-phase
  initialization (**PEP 489**).

* bpo-40521: Make the Unicode dictionary of interned strings
  compatible with subinterpreters. Patch by Victor Stinner.

* bpo-39465: Make "_PyUnicode_FromId()" function compatible with
  subinterpreters. Each interpreter now has an array of identifier
  objects (interned strings decoded from UTF-8). Patch by Victor
  Stinner.


Library
-------

* bpo-42257: Handle empty string in variable executable in
  platform.libc_ver()

* bpo-42772: randrange() now raises a TypeError when step is specified
  without a stop argument.  Formerly, it silently ignored the step
  argument.

* bpo-42759: Fixed equality comparison of "tkinter.Variable" and
  "tkinter.font.Font". Objects which belong to different Tcl
  interpreters are now always different, even if they have the same
  name.

* bpo-42756: Configure LMTP Unix-domain socket to use socket global
  default timeout when a timeout is not explicitly provided.

* bpo-23328: Allow / character in username, password fields on _PROXY
  envars.

* bpo-42740: "typing.get_args()" and "typing.get_origin()" now support
  **PEP 604** union types and **PEP 612** additions to "Callable".

* bpo-42655: "subprocess" *extra_groups* is now correctly passed into
  setgroups() system call.

* bpo-42727: "EnumMeta.__prepare__" now accepts "**kwds" to properly
  support "__init_subclass__"

* bpo-38308: Add optional *weights* to *statistics.harmonic_mean()*.

* bpo-42721: When simple query dialogs ("tkinter.simpledialog"),
  message boxes ("tkinter.messagebox") or color choose dialog
  ("tkinter.colorchooser") are created without arguments *master* and
  *parent*, and the default root window is not yet created, and
  "NoDefaultRoot()" was not called, a new temporal hidden root window
  will be created automatically. It will not be set as the default
  root window and will be destroyed right after closing the dialog
  window. It will help to use these simple dialog windows in programs
  which do not need other GUI.

* bpo-25246: Optimized "collections.deque.remove()".

* bpo-35728: Added a root parameter to "tkinter.font.nametofont()".

* bpo-15303: "tkinter" supports now widgets with boolean value False.

* bpo-42681: Fixed range checks for color and pair numbers in
  "curses".

* bpo-42685: Improved placing of simple query windows in Tkinter (such
  as "tkinter.simpledialog.askinteger()"). They are now centered at
  the center of the parent window if it is specified and shown,
  otherwise at the center of the screen.

* bpo-9694: Argparse help no longer uses the confusing phrase,
  “optional arguments”. It uses “options” instead.

* bpo-1635741: Port the "_thread" extension module to the multiphase
  initialization API (**PEP 489**) and convert its static types to
  heap types.

* bpo-37961: Fix crash in "tracemalloc.Traceback.__repr__()"
  (regressed in Python 3.9).

* bpo-42630: "tkinter" functions and constructors which need a default
  root window raise now "RuntimeError" with descriptive message
  instead of obscure "AttributeError" or "NameError" if it is not
  created yet or cannot be created automatically.

* bpo-42639: "atexit._run_exitfuncs()" now logs callback exceptions
  using "sys.unraisablehook", rather than logging them directly into
  "sys.stderr" and raise the last exception.

* bpo-42644: "logging.disable" will now validate the types and value
  of its parameter. It also now accepts strings representing the
  levels (as does "loging.setLevel") instead of only the numerical
  values.

* bpo-42639: At Python exit, if a callback registered with
  "atexit.register()" fails, its exception is now logged. Previously,
  only some exceptions were logged, and the last exception was always
  silently ignored.

* bpo-36541: Fixed lib2to3.pgen2 to be able to parse PEP-570
  positional only argument syntax.

* bpo-42382: In "importlib.metadata": -  "EntryPoint" objects now
  expose a ".dist" object referencing the "Distribution" when
  constructed from a "Distribution". - Add support for package
  discovery under package normalization rules. - The object returned
  by "metadata()" now has a formally defined protocol called
  "PackageMetadata" with declared support for the ".get_all()" method.
  - Synced with importlib_metadata 3.3.

* bpo-41877: A check is added against misspellings of autospect,
  auto_spec and set_spec being passed as arguments to patch,
  patch.object and create_autospec.

* bpo-39717: [tarfile] update nested exception raising to use "from
  None" or "from e"

* bpo-41877: AttributeError for suspected misspellings of assertions
  on mocks are now pointing out that the cause are misspelled
  assertions and also what to do if the misspelling is actually an
  intended attribute name. The unittest.mock document is also updated
  to reflect the current set of recognised misspellings.

* bpo-41559: Implemented **PEP 612**: added "ParamSpec" and
  "Concatenate" to "typing".  Patch by Ken Jin.

* bpo-42385: StrEnum: fix _generate_next_value_ to return a str

* bpo-31904: Define THREAD_STACK_SIZE for VxWorks.

* bpo-34750: [Enum] "_EnumDict.update()" is now supported

* bpo-42517: Enum: private names do not become members / do not
  generate errors – they remain normal attributes

* bpo-42678: "Enum": call "__init_subclass__" after members have been
  added

* bpo-28964: "ast.literal_eval()" adds line number information (if
  available) in error message for malformed nodes.

* bpo-42470: "random.sample()" no longer warns on a sequence which is
  also a set.

* bpo-31904: "posixpath.expanduser()" returns the input *path*
  unchanged if user home directory is None on VxWorks.

* bpo-42388: Fix subprocess.check_output(…, input=None) behavior when
  text=True to be consistent with that of the documentation and
  universal_newlines=True.

* bpo-34463: Fixed discrepancy between "traceback" and the interpreter
  in formatting of SyntaxError with lineno not set ("traceback" was
  changed to match interpreter).

* bpo-42393: Raise "OverflowError" instead of silent truncation in
  "socket.ntohs()" and "socket.htons()".  Silent truncation was
  deprecated in Python 3.7. Patch by Erlend E. Aasland

* bpo-42222: Harmonized "random.randrange()" argument handling to
  match "range()".

  * The integer test and conversion in "randrange()" now uses
    "operator.index()".

  * Non-integer arguments to "randrange()" are deprecated.

  * The "ValueError" is deprecated in favor of a "TypeError".

  * It now runs a little faster than before.

  (Contributed by Raymond Hettinger and Serhiy Storchaka.)

* bpo-42163: Restore compatibility for "uname_result" around deepcopy
  and _replace.

* bpo-42090: "zipfile.Path.joinpath" now accepts arbitrary arguments,
  same as "pathlib.Path.joinpath".

* bpo-1635741: Port the _csv module to the multi-phase initialization
  API (**PEP 489**).

* bpo-42059: "typing.TypedDict" types created using the alternative
  call-style syntax now correctly respect the "total" keyword argument
  when setting their "__required_keys__" and "__optional_keys__" class
  attributes.

* bpo-41960: Add "globalns" and "localns" parameters to the
  "inspect.signature()" and "inspect.Signature.from_callable()".

* bpo-41907: fix "format()" behavior for "IntFlag"

* bpo-41891: Ensure asyncio.wait_for waits for task completion

* bpo-24792: Fixed bug where "zipimporter" sometimes reports an
  incorrect cause of import errors.

* bpo-31904: Fix site and sysconfig modules for VxWorks RTOS which has
  no home directories.

* bpo-41462: Add "os.set_blocking()" support for VxWorks RTOS.

* bpo-40219: Lowered "tkinter.ttk.LabeledScale" dummy widget to
  prevent hiding part of the content label.

* bpo-37193: Fixed memory leak in "socketserver.ThreadingMixIn"
  introduced in Python 3.7.

* bpo-39068: Fix initialization race condition in "a85encode()" and
  "b85encode()" in "base64". Patch by Brandon Stansbury.


Documentation
-------------

* bpo-17140: Add documentation for the
  "multiprocessing.pool.ThreadPool" class.

* bpo-34398: Prominently feature listings from the glossary in
  documentation search results. Patch by Ammar Askar.


Tests
-----

* bpo-42794: Update test_nntplib to use official group name of
  news.aioe.org for testing. Patch by Dong-hee Na.

* bpo-31904: Skip some asyncio tests on VxWorks.

* bpo-42641: Enhance "test_select.test_select()": it now takes 500 ms
  rather than 10 seconds. Use Python rather than a shell to make the
  test more portable.

* bpo-31904: Skip some tests in _test_all_chown_common() on VxWorks.

* bpo-42199: Fix bytecode helper assertNotInBytecode.

* bpo-41443: Add more attribute checking in test_posix.py

* bpo-31904: Disable os.popen and impacted tests on VxWorks

* bpo-41439: Port test_ssl and test_uuid to VxWorks RTOS.


Build
-----

* bpo-42692: Fix __builtin_available check on older compilers. Patch
  by Joshua Root.

* bpo-27640: Added "--disable-test-modules" option to the "configure"
  script: don’t build nor install test modules. Patch by Xavier de
  Gaye, Thomas Petazzoni and Peixing Xin.

* bpo-42604: Now all platforms use a value for the “EXT_SUFFIX” build
  variable derived from SOABI (for instance in freeBSD, “EXT_SUFFIX”
  is now “.cpython-310d.so” instead of “.so”). Previously only Linux,
  Mac and VxWorks were using a value for “EXT_SUFFIX” that included
  “SOABI”.

* bpo-42598: Fix implicit function declarations in configure which
  could have resulted in incorrect configuration checks.  Patch
  contributed by Joshua Root.

* bpo-31904: Enable libpython3.so for VxWorks.

* bpo-29076: Add fish shell support to macOS installer.


macOS
-----

* bpo-42361: Update macOS installer build to use Tcl/Tk 8.6.11 (rc2,
  expected to be final release).

* bpo-41837: Update macOS installer build to use OpenSSL 1.1.1i.

* bpo-42584: Update macOS installer to use SQLite 3.34.0.


Tools/Demos
-----------

* bpo-42726: Fixed Python 3 compatibility issue with gdb/libpython.py
  handling of attribute dictionaries.

* bpo-42613: Fix "freeze.py" tool to use the prope config and library
  directories. Patch by Victor Stinner.


C API
-----

* bpo-42591: Export the "Py_FrozenMain()" function: fix a Python 3.9.0
  regression. Python 3.9 uses "-fvisibility=hidden" and the function
  was not exported explicitly and so not exported.

* bpo-32381: Remove the private "_Py_fopen()" function which is no
  longer needed. Use "_Py_wfopen()" or "_Py_fopen_obj()" instead.
  Patch by Victor Stinner.

* bpo-1635741: Port "resource" extension module to module state

* bpo-42111: Update the "xxlimited" module to be a better example of
  how to use the limited C API.

* bpo-40052: Fix an alignment build warning/error in function
  "PyVectorcall_Function()". Patch by Andreas Schneider, Antoine
  Pitrou and Petr Viktorin.


Python 3.10.0 alpha 3
=====================

*Release date: 2020-12-07*


Security
--------

* bpo-40791: Add "volatile" to the accumulator variable in
  "hmac.compare_digest", making constant-time-defeating optimizations
  less likely.


Core and Builtins
-----------------

* bpo-42576: "types.GenericAlias" will now raise a "TypeError" when
  attempting to initialize with a keyword argument.  Previously, this
  would cause the interpreter to crash if the interpreter was compiled
  with debug symbols. This does not affect interpreters compiled for
  release.  Patch by Ken Jin.

* bpo-42536: Several built-in and standard library types now ensure
  that their internal result tuples are always tracked by the *garbage
  collector*:

  * "collections.OrderedDict.items()"

  * "dict.items()"

  * "enumerate()"

  * "functools.reduce()"

  * "itertools.combinations()"

  * "itertools.combinations_with_replacement()"

  * "itertools.permutations()"

  * "itertools.product()"

  * "itertools.zip_longest()"

  * "zip()"

  Previously, they could have become untracked by a prior garbage
  collection. Patch by Brandt Bucher.

* bpo-42500: Improve handling of exceptions near recursion limit.
  Converts a number of Fatal Errors in RecursionErrors.

* bpo-42246: PEP 626: After a return, the f_lineno attribute of a
  frame is always the last line executed.

* bpo-42435: Speed up comparison of bytes objects with non-bytes
  objects when option "-b" is specified. Speed up comparison of
  bytarray objects with non-buffer object.

* bpo-1635741: Port the "_warnings" extension module to the multi-
  phase initialization API (**PEP 489**). Patch by Victor Stinner.

* bpo-41686: On Windows, the "SIGINT" event, "_PyOS_SigintEvent()", is
  now created even if Python is configured to not install signal
  handlers (if "PyConfig.install_signal_handlers" equals to 0, or
  "Py_InitializeEx(0)").

* bpo-42381: Allow assignment expressions in set literals and set
  comprehensions as per PEP 572. Patch by Pablo Galindo.

* bpo-42202: Change function parameters annotations internal
  representation to tuple of strings. Patch provided by Yurii Karabas.

* bpo-42374: Fix a regression introduced by the new parser, where an
  unparenthesized walrus operator was not allowed within generator
  expressions.

* bpo-42316: Allow an unparenthesized walrus in subscript indexes.

* bpo-42349: Make sure that the compiler front-end produces a well-
  formed control flow graph. Be be more aggressive in the compiler
  back-end, as it is now safe to do so.

* bpo-42296: On Windows, fix a regression in signal handling which
  prevented to interrupt a program using CTRL+C. The signal handler
  can be run in a thread different than the Python thread, in which
  case the test deciding if the thread can handle signals is wrong.

* bpo-42332: "types.GenericAlias" objects can now be the targets of
  weakrefs.

* bpo-42282: Optimise constant subexpressions that appear as part of
  named expressions (previously the AST optimiser did not descend into
  named expressions). Patch by Nick Coghlan.

* bpo-42266: Fixed a bug with the LOAD_ATTR opcode cache that was not
  respecting monkey-patching a class-level attribute to make it a
  descriptor. Patch by Pablo Galindo.

* bpo-40077: Convert "queue" to use heap types.

* bpo-42246: Improved accuracy of line tracing events and f_lineno
  attribute of Frame objects. See PEP 626 for details.

* bpo-40077: Convert "mmap" to use heap types.

* bpo-42233: Allow "GenericAlias" objects to use union type
  expressions. This allows expressions like "list[int] | dict[float,
  str]" where previously a "TypeError" would have been thrown.  This
  also fixes union type expressions not de-duplicating "GenericAlias"
  objects. (Contributed by Ken Jin in bpo-42233.)

* bpo-26131: The import system triggers a "ImportWarning" when it
  falls back to using "load_module()".


Library
-------

* bpo-5054: CGIHTTPRequestHandler.run_cgi() HTTP_ACCEPT improperly
  parsed. Replace the special purpose getallmatchingheaders with
  generic get_all method and add relevant tests.

  Original Patch by Martin Panter. Modified by Senthil Kumaran.

* bpo-42562: Fix issue when dis failed to parse function that has no
  line numbers. Patch provided by Yurii Karabas.

* bpo-17735: "inspect.findsource()" now raises "OSError" instead of
  "IndexError" when "co_lineno" of a code object is greater than the
  file length. This can happen, for example, when a file is edited
  after it was imported.  PR by Irit Katriel.

* bpo-42116: Fix handling of trailing comments by
  "inspect.getsource()".

* bpo-42532: Remove unexpected call of "__bool__" when passing a
  "spec_arg" argument to a Mock.

* bpo-38200: Added itertools.pairwise()

* bpo-41818: Fix test_master_read() so that it succeeds on all
  platforms that either raise OSError or return b”” upon reading from
  master.

* bpo-42487: ChainMap.__iter__ no longer calls __getitem__ on
  underlying maps

* bpo-42482: "TracebackException" no longer holds a reference to the
  exception’s traceback object. Consequently, instances of
  TracebackException for equivalent but non-equal exceptions now
  compare as equal.

* bpo-41818: Make test_openpty() avoid unexpected success due to
  number of rows and/or number of columns being == 0.

* bpo-42392: Remove loop parameter from "asyncio.subprocess" and
  "asyncio.tasks" functions. Patch provided by Yurii Karabas.

* bpo-42392: Remove loop parameter from "asyncio.open_connection" and
  "asyncio.start_server" functions. Patch provided by Yurii Karabas.

* bpo-28468: Add "platform.freedesktop_os_release()" function to parse
  freedesktop.org "os-release" files.

* bpo-42299: Removed the "formatter" module, which was deprecated in
  Python 3.4. It is somewhat obsolete, little used, and not tested. It
  was originally scheduled to be removed in Python 3.6, but such
  removals were delayed until after Python 2.7 EOL. Existing users
  should copy whatever classes they use into their code. Patch by
  Dong-hee Na and and Terry J. Reedy.

* bpo-26131: Deprecate zipimport.zipimporter.load_module() in favour
  of exec_module().

* bpo-41818: Updated tests for the pty library. test_basic() has been
  changed to test_openpty(); this additionally checks if slave termios
  and slave winsize are being set properly by pty.openpty(). In order
  to add support for FreeBSD, NetBSD, OpenBSD, and Darwin, this also
  adds test_master_read(), which demonstrates that pty.spawn() should
  not depend on an OSError to exit from its copy loop.

* bpo-42392: Remove loop parameter from "__init__" in all
  "asyncio.locks" and "asyncio.Queue" classes. Patch provided by Yurii
  Karabas.

* bpo-15450: Make "filecmp.dircmp" respect subclassing. Now the
  "filecmp.dircmp.subdirs" behaves as expected when subclassing
  dircmp.

* bpo-42413: The exception "socket.timeout" is now an alias of
  "TimeoutError".

* bpo-31904: Support signal module on VxWorks.

* bpo-42406: We fixed an issue in "pickle.whichmodule" in which
  importing "multiprocessing" could change the how pickle identifies
  which module an object belongs to, potentially breaking the
  unpickling of those objects.

* bpo-42403: Simplify the "importlib" external bootstrap code:
  "importlib._bootstrap_external" now uses regular imports to import
  builtin modules. When it is imported, the builtin "__import__()"
  function is already fully working and so can be used to import
  builtin modules like "sys". Patch by Victor Stinner.

* bpo-1635741: Convert _sre module types to heap types (PEP 384).
  Patch by Erlend E. Aasland.

* bpo-42375: subprocess module update for DragonFlyBSD support.

* bpo-41713: Port the "_signal" extension module to the multi-phase
  initialization API (**PEP 489**). Patch by Victor Stinner and
  Mohamed Koubaa.

* bpo-37205: "time.time()", "time.perf_counter()" and
  "time.monotonic()" functions can no longer fail with a Python fatal
  error, instead raise a regular Python exception on failure.

* bpo-42328: Fixed "tkinter.ttk.Style.map()". The function accepts now
  the representation of the default state as empty sequence (as
  returned by "Style.map()"). The structure of the result is now the
  same on all platform and does not depend on the value of
  "wantobjects".

* bpo-42345: Fix various issues with "typing.Literal" parameter
  handling (flatten, deduplicate, use type to cache key). Patch
  provided by Yurii Karabas.

* bpo-37205: "time.perf_counter()" on Windows and "time.monotonic()"
  on macOS are now system-wide. Previously, they used an offset
  computed at startup to reduce the precision loss caused by the float
  type. Use "time.perf_counter_ns()" and "time.monotonic_ns()" added
  in Python 3.7 to avoid this precision loss.

* bpo-42318: Fixed support of non-BMP characters in "tkinter" on
  macOS.

* bpo-42350: Fix the "threading.Thread" class at fork: do nothing if
  the thread is already stopped (ex: fork called at Python exit).
  Previously, an error was logged in the child process.

* bpo-42333: Port _ssl extension module to heap types.

* bpo-42014: The "onerror" callback from "shutil.rmtree" now receives
  correct function when "os.open" fails.

* bpo-42237: Fix "os.sendfile()" on illumos.

* bpo-42308: Add "threading.__excepthook__" to allow retrieving the
  original value of "threading.excepthook()" in case it is set to a
  broken or a different value. Patch by Mario Corchero.

* bpo-42131: Implement PEP 451/spec methods on zipimport.zipimporter:
  find_spec(), create_module(), and exec_module().

  This also allows for the documented deprecation of find_loader(),
  find_module(), and load_module().

* bpo-41877: Mock objects which are not unsafe will now raise an
  AttributeError if an attribute with the prefix asert, aseert, or
  assrt is accessed, in addition to this already happening for the
  prefixes assert or assret.

* bpo-42264: "sqlite3.OptimizedUnicode" has been undocumented and
  obsolete since Python 3.3, when it was made an alias to "str".  It
  is now deprecated, scheduled for removal in Python 3.12.

* bpo-42251: Added "threading.gettrace()" and "threading.getprofile()"
  to retrieve the functions set by "threading.settrace()" and
  "threading.setprofile()" respectively. Patch by Mario Corchero.

* bpo-42249: Fixed writing binary Plist files larger than 4 GiB.

* bpo-42236: On Unix, the "os.device_encoding()" function now returns
  "'UTF-8'" rather than the device encoding if the Python UTF-8 Mode
  is enabled.

* bpo-41754: webbrowser: Ignore *NotADirectoryError* when calling
  "xdg-settings".

* bpo-42183: Fix a stack overflow error for asyncio Task or Future
  repr().

  The overflow occurs under some circumstances when a Task or Future
  recursively returns itself.

* bpo-42140: Improve asyncio.wait function to create the futures set
  just one time.

* bpo-42133: Update various modules in the stdlib to fall back on
  "__spec__.loader" when "__loader__" isn’t defined on a module.

* bpo-26131: The "load_module()" methods found in importlib now
  trigger a DeprecationWarning.

* bpo-39825: Windows: Change "sysconfig.get_config_var('EXT_SUFFIX')"
  to the expected full "platform_tag.extension" format. Previously it
  was hard-coded to ".pyd", now it is compatible with
  "distutils.sysconfig" and will result in something like
  ".cp38-win_amd64.pyd". This brings windows into conformance with the
  other platforms.

* bpo-26389: The "traceback.format_exception()",
  "traceback.format_exception_only()", and
  "traceback.print_exception()" functions can now take an exception
  object as a positional-only argument.

* bpo-41889: Enum: fix regression involving inheriting a multiply
  inherited enum

* bpo-41861: Convert "sqlite3" to use heap types (PEP 384). Patch by
  Erlend E. Aasland.

* bpo-40624: Added support for the XPath "!=" operator in xml.etree

* bpo-28850: Fix "pprint.PrettyPrinter.format()" overrides being
  ignored for contents of small containers. The "pprint._safe_repr()"
  function was removed.

* bpo-41625: Expose the "splice()" as "os.splice()" in the "os"
  module. Patch by Pablo Galindo

* bpo-34215: Clarify the error message for
  "asyncio.IncompleteReadError" when "expected" is "None".

* bpo-41543: Add async context manager support for
  contextlib.nullcontext.

* bpo-21041: "pathlib.PurePath.parents" now supports negative
  indexing. Patch contributed by Yaroslav Pankovych.

* bpo-41332: Added missing connect_accepted_socket() method to
  "asyncio.AbstractEventLoop".

* bpo-12800: Extracting a symlink from a tarball should succeed and
  overwrite the symlink if it already exists. The fix is to remove the
  existing file or symlink before extraction. Based on patch by Chris
  AtLee, Jeffrey Kintscher, and Senthil Kumaran.

* bpo-40968: "urllib.request" and "http.client" now send "http/1.1"
  ALPN extension during TLS handshake when no custom context is
  supplied.

* bpo-41001: Add func:"os.eventfd" to provide a low level interface
  for Linux’s event notification file descriptor.

* bpo-40816: Add AsyncContextDecorator to contextlib to support async
  context manager as a decorator.

* bpo-40550: Fix time-of-check/time-of-action issue in
  subprocess.Popen.send_signal.

* bpo-39411: Add an "is_async" identifier to "pyclbr"’s "Function"
  objects. Patch by Batuhan Taskaya

* bpo-35498: Add slice support to "pathlib.PurePath.parents".


Documentation
-------------

* bpo-42238: Tentative to deprecate "make suspicious" by first
  removing it from the CI and documentation builds, but keeping it
  around for manual uses.

* bpo-42153: Fix the URL for the IMAP protocol documents.

* bpo-41028: Language and version switchers, previously maintained in
  every cpython branches, are now handled by docsbuild-script.


Tests
-----

* bpo-41473: Re-enable test_gdb on gdb 9.2 and newer:
  https://bugzilla.redhat.com/show_bug.cgi?id=1866884 bug is fixed in
  gdb 10.1.

* bpo-42553: Fix "test_asyncio.test_call_later()" race condition:
  don’t measure asyncio performance in the "call_later()" unit test.
  The test failed randomly on the CI.

* bpo-31904: Fix test_netrc on VxWorks: create temporary directories
  using temp_cwd().

* bpo-31904: skip test_getaddrinfo_ipv6_scopeid_symbolic and
  test_getnameinfo_ipv6_scopeid_symbolic on VxWorks

* bpo-31904: skip test_test of test_mailcap on VxWorks

* bpo-31904: add shell requirement for test_pipes

* bpo-31904: skip some tests related to fifo on VxWorks

* bpo-31904: Fix test_doctest.py failures for VxWorks.

* bpo-40754: Include "_testinternalcapi" module in Windows installer
  for test suite

* bpo-41561: test_ssl: skip test_min_max_version_mismatch when TLS 1.0
  is not available

* bpo-31904: Fix os module failures for VxWorks RTOS.

* bpo-31904: Fix fifo test cases for VxWorks RTOS.


Build
-----

* bpo-31904: remove libnet dependency from detect_socket() for VxWorks

* bpo-42398: Fix a race condition in “make regen-all” when make -jN
  option is used to run jobs in parallel. The clinic.py script now
  only use atomic write to write files. Moveover, generated files are
  now left unchanged if the content does not change, to not change the
  file modification time.

* bpo-41617: Fix building "pycore_bitutils.h" internal header on old
  clang version without "__builtin_bswap16()" (ex: Xcode 4.6.3 on Mac
  OS X 10.7). Patch by Joshua Root and Victor Stinner.

* bpo-38823: It is no longer possible to build the "_ctypes" extension
  module without "wchar_t" type: remove "CTYPES_UNICODE" macro.
  Anyway, the "wchar_t" type is required to build Python. Patch by
  Victor Stinner.

* bpo-42087: Support was removed for AIX 5.3 and below. See bpo-40680.

* bpo-40998: Addressed three compiler warnings found by undefined
  behavior sanitizer (ubsan).


Windows
-------

* bpo-42120: Remove macro definition of "copysign" (to "_copysign") in
  headers.

* bpo-38506: The Windows launcher now properly handles Python 3.10
  when listing installed Python versions.


macOS
-----

* bpo-42504: Fix build on macOS Big Sur when
  MACOSX_DEPLOYMENT_TARGET=11

* bpo-41116: Ensure distutils.unixxcompiler.find_library_file can find
  system provided libraries on macOS 11.

* bpo-41100: Add support for macOS 11 and Apple Silicon systems.

  It is now possible to build “Universal 2” binaries using “–enable-
  universalsdk –with-universal-archs=universal2”.

  Binaries build on later macOS versions can be deployed back to older
  versions (tested up to macOS 10.9), when using the correct
  deployment target. This is tested using Xcode 11 and later.

* bpo-42232: Added Darwin specific madvise options to mmap module.

* bpo-38443: The "--enable-universalsdk" and "--with-universal-archs"
  options for the configure script now check that the specified
  architectures can be used.


IDLE
----

* bpo-42508: Keep IDLE running on macOS.  Remove obsolete workaround
  that prevented running files with shortcuts when using new
  universal2 installers built on macOS 11.

* bpo-42426: Fix reporting offset of the RE error in searchengine.

* bpo-42415: Get docstrings for IDLE calltips more often by using
  inspect.getdoc.


Tools/Demos
-----------

* bpo-42212: The smelly.py script now also checks the Python dynamic
  library and extension modules, not only the Python static library.
  Make also the script more verbose: explain what it does.

* bpo-36310: Allow "Tools/i18n/pygettext.py" to detect calls to
  "gettext" in f-strings.


C API
-----

* bpo-42423: The "PyType_FromSpecWithBases()" and
  "PyType_FromModuleAndSpec()" functions now accept a single class as
  the *bases* argument.

* bpo-1635741: Port "select" extension module to multiphase
  initialization (**PEP 489**).

* bpo-1635741: Port _posixsubprocess extension module to multiphase
  initialization (**PEP 489**).

* bpo-1635741: Port _posixshmem extension module to multiphase
  initialization (**PEP 489**)

* bpo-1635741: Port _struct extension module to multiphase
  initialization (**PEP 489**)

* bpo-1635741: Port "spwd" extension module to multiphase
  initialization (**PEP 489**)

* bpo-1635741: Port "gc" extension module to multiphase initialization
  (**PEP 489**)

* bpo-1635741: Port _queue extension module to multiphase
  initialization (**PEP 489**)

* bpo-39573: Convert "Py_TYPE()" and "Py_SIZE()" back to macros to
  allow using them as an l-value. Many third party C extension modules
  rely on the ability of using Py_TYPE() and Py_SIZE() to set an
  object type and size: "Py_TYPE(obj) = type;" and "Py_SIZE(obj) =
  size;".

* bpo-1635741: Port "symtable" extension module to multiphase
  initialization (**PEP 489**)

* bpo-1635741: Port "grp" and "pwd" extension modules to multiphase
  initialization (**PEP 489**)

* bpo-1635741: Port _random extension module to multiphase
  initialization (**PEP 489**)

* bpo-1635741: Port _hashlib extension module to multiphase
  initialization (**PEP 489**)

* bpo-41713: Removed the undocumented "PyOS_InitInterrupts()"
  function. Initializing Python already implicitly installs signal
  handlers: see "PyConfig.install_signal_handlers". Patch by Victor
  Stinner.

* bpo-40170: The "Py_TRASHCAN_BEGIN" macro no longer accesses
  PyTypeObject attributes, but now can get the condition by calling
  the new private "_PyTrash_cond()" function which hides
  implementation details.

* bpo-42260: "Py_GetPath()", "Py_GetPrefix()", "Py_GetExecPrefix()",
  "Py_GetProgramFullPath()", "Py_GetPythonHome()" and
  "Py_GetProgramName()" functions now return "NULL" if called before
  "Py_Initialize()" (before Python is initialized). Use the new Python
  Initialization Configuration API to get the Python Path
  Configuration.. Patch by Victor Stinner.

* bpo-42260: The "PyConfig_Read()" function now only parses
  "PyConfig.argv" arguments once: "PyConfig.parse_argv" is set to "2"
  after arguments are parsed. Since Python arguments are strippped
  from "PyConfig.argv", parsing arguments twice would parse the
  application options as Python options.

* bpo-42262: Added "Py_NewRef()" and "Py_XNewRef()" functions to
  increment the reference count of an object and return the object.
  Patch by Victor Stinner.

* bpo-42260: When "Py_Initialize()" is called twice, the second call
  now updates more "sys" attributes for the configuration, rather than
  only "sys.argv". Patch by Victor Stinner.

* bpo-41832: The "PyType_FromModuleAndSpec()" function now accepts
  NULL "tp_doc" slot.

* bpo-1635741: Added "PyModule_AddObjectRef()" function: similar to
  "PyModule_AddObject()" but don’t steal a reference to the value on
  success. Patch by Victor Stinner.

* bpo-42171: The "METH_FASTCALL" calling convention is added to the
  limited API. The functions  "PyModule_AddType()",
  "PyType_FromModuleAndSpec()", "PyType_GetModule()" and
  "PyType_GetModuleState()" are added to the limited API on Windows.

* bpo-42085: Add dedicated entry to PyAsyncMethods for sending values

* bpo-41073: "PyType_GetSlot()" can now accept static types.

* bpo-30459: "PyList_SET_ITEM()", "PyTuple_SET_ITEM()" and
  "PyCell_SET()" macros can no longer be used as l-value or r-value.
  For example, "x = PyList_SET_ITEM(a, b, c)" and "PyList_SET_ITEM(a,
  b, c) = x" now fail with a compiler error. It prevents bugs like "if
  (PyList_SET_ITEM (a, b, c) < 0) ..." test. Patch by Zackery Spytz
  and Victor Stinner.


Python 3.10.0 alpha 2
=====================

*Release date: 2020-11-03*


Security
--------

* bpo-42103: Prevented potential DoS attack via CPU and RAM exhaustion
  when processing malformed Apple Property List files in binary
  format.

* bpo-42051: The "plistlib" module no longer accepts entity
  declarations in XML plist files to avoid XML vulnerabilities. This
  should not affect users as entity declarations are not used in
  regular plist files.


Core and Builtins
-----------------

* bpo-42236: If the "nl_langinfo(CODESET)" function returns an empty
  string, Python now uses UTF-8 as the filesystem encoding. Patch by
  Victor Stinner.

* bpo-42218: Fixed a bug in the PEG parser that was causing crashes in
  debug mode. Now errors are checked in left-recursive rules to avoid
  cases where such errors do not get handled in time and appear as
  long-distance crashes in other places.

* bpo-42214: Fixed a possible crash in the PEG parser when checking
  for the ‘!=’ token in the "barry_as_flufl" rule. Patch by Pablo
  Galindo.

* bpo-42206: Propagate and raise the errors caused by
  "PyAST_Validate()" in the parser.

* bpo-41796: The "ast" module internal state is now per interpreter.
  Patch by Victor Stinner.

* bpo-42143: Fix handling of errors during creation of
  "PyFunctionObject", which resulted in operations on uninitialized
  memory. Patch by Yonatan Goldschmidt.

* bpo-41659: Fix a bug in the parser, where a curly brace following a
  "primary" didn’t fail immediately. This led to invalid expressions
  like "a {b}" to throw a "SyntaxError" with a wrong offset, or
  invalid expressions ending with a curly brace like "a {" to not fail
  immediately in the REPL.

* bpo-42150: Fix possible buffer overflow in the new parser when
  checking for continuation lines. Patch by Pablo Galindo.

* bpo-42123: Run the parser two times. On the first run, disable all
  the rules that only generate better error messages to gain
  performance. If there’s a parse failure, run the parser a second
  time with those enabled.

* bpo-42093: The "LOAD_ATTR" instruction now uses new “per opcode
  cache” mechanism and it is about 36% faster now. Patch by Pablo
  Galindo and Yury Selivanov.

* bpo-42030: Support for the legacy AIX-specific shared library
  loading support has been removed. All versions of AIX since 4.3 have
  supported and defaulted to using the common Unix mechanism instead.

* bpo-41984: The garbage collector now tracks all user-defined
  classes. Patch by Brandt Bucher.

* bpo-41993: Fixed potential issues with removing not completely
  initialized module from "sys.modules" when import fails.

* bpo-41979: Star-unpacking is now allowed for with item’s targets in
  the PEG parser.

* bpo-41974: Removed special methods "__int__", "__float__",
  "__floordiv__", "__mod__", "__divmod__", "__rfloordiv__", "__rmod__"
  and "__rdivmod__" of the "complex" class.  They always raised a
  "TypeError".

* bpo-41902: Micro optimization when compute "sq_item" and
  "mp_subscript" of "range". Patch by Dong-hee Na.

* bpo-41894: When loading a native module and a load failure occurs,
  prevent a possible UnicodeDecodeError when not running in a UTF-8
  locale by decoding the load error message using the current locale’s
  encoding.

* bpo-41902: Micro optimization for range.index if step is 1. Patch by
  Dong-hee Na.

* bpo-41435: Add "sys._current_exceptions()" function to retrieve a
  dictionary mapping each thread’s identifier to the topmost exception
  currently active in that thread at the time the function is called.

* bpo-38605: Enable "from __future__ import annotations" (**PEP 563**)
  by default. The values found in "__annotations__" dicts are now
  strings, e.g. "{"x": "int"}" instead of "{"x": int}".


Library
-------

* bpo-35455: On Solaris, "thread_time()" is now implemented with
  "gethrvtime()" because "clock_gettime(CLOCK_THREAD_CPUTIME_ID)" is
  not always available. Patch by Jakub Kulik.

* bpo-42233: The "repr()" of "typing" types containing Generic Alias
  Types previously did not show the parameterized types in the
  "GenericAlias".  They have now been changed to do so.

* bpo-29566: "binhex.binhex()" consistently writes macOS 9 line
  endings.

* bpo-26789: The "logging.FileHandler" class now keeps a reference to
  the builtin "open()" function to be able to open or reopen the file
  during Python finalization. Fix errors like: "NameError: name 'open'
  is not defined". Patch by Victor Stinner.

* bpo-42157: Removed the "unicodedata.ucnhash_CAPI" attribute which
  was an internal PyCapsule object. The related private
  "_PyUnicode_Name_CAPI" structure was moved to the internal C API.
  Patch by Victor Stinner.

* bpo-42157: Convert the "unicodedata" extension module to the
  multiphase initialization API (**PEP 489**) and convert the
  "unicodedata.UCD" static type to a heap type. Patch by Mohamed
  Koubaa and Victor Stinner.

* bpo-42146: Fix memory leak in "subprocess.Popen()" in case an uid
  (gid) specified in "user" ("group", "extra_groups") overflows
  "uid_t" ("gid_t").

* bpo-42103: "InvalidFileException" and "RecursionError" are now the
  only errors caused by loading malformed binary Plist file
  (previously ValueError and TypeError could be raised in some
  specific cases).

* bpo-41490: In "importlib.resources", ".path" method is more
  aggressive about releasing handles to zipfile objects early,
  enabling use-cases like certifi to leave the context open but delete
  the underlying zip file.

* bpo-41052: Pickling heap types implemented in C with protocols 0 and
  1 raises now an error instead of producing incorrect data.

* bpo-42089: In "importlib.metadata.PackageNotFoundError", make
  reference to the package metadata being missing to improve the user
  experience.

* bpo-41491: plistlib: fix parsing XML plists with hexadecimal integer
  values

* bpo-42065: Fix an incorrectly formatted error from
  "_codecs.charmap_decode()" when called with a mapped value outside
  the range of valid Unicode code points. PR by Max Bernstein.

* bpo-41966: Fix pickling pure Python "datetime.time" subclasses.
  Patch by Dean Inwood.

* bpo-19270: "sched.scheduler.cancel()" will now cancel the correct
  event, if two events with same priority are scheduled for the same
  time. Patch by Bar Harel.

* bpo-28660: "textwrap.wrap()" now attempts to break long words after
  hyphens when "break_long_words=True" and "break_on_hyphens=True".

* bpo-35823: Use "vfork()" instead of "fork()" for
  "subprocess.Popen()" on Linux to improve performance in cases where
  it is deemed safe.

* bpo-42043: Add support for "zipfile.Path" inheritance.
  "zipfile.Path.is_file()" now returns False for non-existent names.
  "zipfile.Path" objects now expose a ".filename" attribute and rely
  on that to resolve ".name" and ".parent" when the "Path" object is
  at the root of the zipfile.

* bpo-42021: Fix possible ref leaks in "sqlite3" module init.

* bpo-39101: Fixed tests using IsolatedAsyncioTestCase from hanging on
  BaseExceptions.

* bpo-41976: Fixed a bug that was causing "ctypes.util.find_library()"
  to return "None" when triying to locate a library in an environment
  when gcc>=9 is available and "ldconfig" is not. Patch by Pablo
  Galindo

* bpo-41943: Fix bug where TestCase.assertLogs doesn’t correctly
  filter messages by level.

* bpo-41923: Implement **PEP 613**, introducing "typing.TypeAlias"
  annotation.

* bpo-41905: A new function in abc: *update_abstractmethods* to re-
  calculate an abstract class’s abstract status. In addition,
  *dataclass* has been changed to call this function.

* bpo-23706: Added *newline* parameter to "pathlib.Path.write_text()".

* bpo-41876: Tkinter font class repr uses font name

* bpo-41831: "str()" for the "type" attribute of the "tkinter.Event"
  object always returns now the numeric code returned by Tk instead of
  the name of the event type.

* bpo-39337: "encodings.normalize_encoding()" now ignores non-ASCII
  characters.

* bpo-41747: Ensure all methods that generated from
  "dataclasses.dataclass()" objects now have the proper "__qualname__"
  attribute referring to the class they belong to. Patch by Batuhan
  Taskaya.

* bpo-30681: Handle exceptions caused by unparsable date headers when
  using email “default” policy.  Patch by Tim Bell, Georges Toth

* bpo-41586: Add F_SETPIPE_SZ and F_GETPIPE_SZ to fcntl module. Allow
  setting pipesize on subprocess.Popen.

* bpo-41229: Add "contextlib.aclosing" for deterministic cleanup of
  async generators which is analogous to "contextlib.closing" for non-
  async generators. Patch by Joongi Kim and John Belmonte.

* bpo-16396: Allow "ctypes.wintypes" to be imported on non-Windows
  systems.

* bpo-4356: Add a key function to the bisect module.

* bpo-40592: "shutil.which()" now ignores empty entries in "PATHEXT"
  instead of treating them as a match.

* bpo-40492: Fix "--outfile" for "cProfile" / "profile" not writing
  the output file in the original directory when the program being
  profiled changes the working directory.  PR by Anthony Sottile.

* bpo-34204: The "shelve" module now uses "pickle.DEFAULT_PROTOCOL" by
  default instead of "pickle" protocol "3".

* bpo-27321: Fixed KeyError exception when flattening an email to a
  string attempts to replace a non-existent Content-Transfer-Encoding
  header.

* bpo-38976: The "http.cookiejar" module now supports the parsing of
  cookies in CURL-style cookiejar files through MozillaCookieJar on
  all platforms. Previously, such cookie entries would be silently
  ignored when loading a cookiejar with such entries.

  Additionally, the HTTP Only attribute is persisted in the object,
  and will be correctly written to file if the MozillaCookieJar object
  is subsequently dumped.


Documentation
-------------

* bpo-42061: Document __format__ functionality for IP addresses.

* bpo-41910: Document the default implementation of "object.__eq__".

* bpo-42010: Clarify that subscription expressions are also valid for
  certain *classes* and *types* in the standard library, and for user-
  defined classes and types if the classmethod "__class_getitem__()"
  is provided.

* bpo-41805: Documented generic alias type and "types.GenericAlias".
  Also added an entry in glossary for *generic types*.

* bpo-39693: Fix tarfile’s extractfile documentation

* bpo-39416: Document some restrictions on the default string
  representations of numeric classes.


Tests
-----

* bpo-41739: Fix
  test_logging.test_race_between_set_target_and_flush(): the test now
  waits until all threads complete to avoid leaking running threads.

* bpo-41970: Avoid a test failure in "test_lib2to3" if the module has
  already imported at the time the test executes. Patch by Pablo
  Galindo.

* bpo-41944: Tests for CJK codecs no longer call "eval()" on content
  received via HTTP.

* bpo-41306: Fixed a failure in "test_tk.test_widgets.ScaleTest"
  happening when executing the test with Tk 8.6.10.


Build
-----

* bpo-38980: Add "-fno-semantic-interposition" to both the compile and
  link line when building with "--enable-optimizations". Patch by
  Victor Stinner and Pablo Galindo.


Windows
-------

* bpo-38439: Updates the icons for IDLE in the Windows Store package.

* bpo-38252: Use 8-byte step to detect ASCII sequence in 64-bit
  Windows build.

* bpo-39107: Update Tcl and Tk to 8.6.10 in Windows installer.

* bpo-41557: Update Windows installer to use SQLite 3.33.0.

* bpo-38324: Avoid Unicode errors when accessing certain locale data
  on Windows.


macOS
-----

* bpo-41471: Ignore invalid prefix lengths in system proxy excludes.


IDLE
----

* bpo-33987: Mostly finish using ttk widgets, mainly for editor,
  settings, and searches. Some patches by Mark Roseman.

* bpo-40511: Typing opening and closing parentheses inside the
  parentheses of a function call will no longer cause unnecessary
  “flashing” off and on of an existing open call-tip, e.g. when typed
  in a string literal.

* bpo-38439: Add a 256×256 pixel IDLE icon to the Windows .ico file.
  Created by Andrew Clover. Remove the low-color gif variations from
  the .ico file.


C API
-----

* bpo-42157: The private "_PyUnicode_Name_CAPI" structure of the
  PyCapsule API "unicodedata.ucnhash_CAPI" has been moved to the
  internal C API. Patch by Victor Stinner.

* bpo-42015: Fix potential crash in deallocating method objects when
  dynamically allocated "PyMethodDef"’s lifetime is managed through
  the "self" argument of a "PyCFunction".

* bpo-40423: The "subprocess" module and "os.closerange" will now use
  the "close_range(low, high, flags)" syscall when it is available for
  more efficient closing of ranges of descriptors.

* bpo-41845: "PyObject_GenericGetDict()" is available again in the
  limited API when targeting 3.10 or later.

* bpo-40422: Add "_Py_closerange" function to provide performant
  closing of a range of file descriptors.

* bpo-41986: "Py_FileSystemDefaultEncodeErrors" and "Py_UTF8Mode" are
  available again in limited API.

* bpo-41756: Add "PyIter_Send" function to allow sending value into
  generator/coroutine/iterator without raising StopIteration exception
  to signal return.

* bpo-41784: Added "PyUnicode_AsUTF8AndSize" to the limited C API.


Python 3.10.0 alpha 1
=====================

*Release date: 2020-10-05*


Security
--------

* bpo-41304: Fixes "python3x._pth" being ignored on Windows, caused by
  the fix for bpo-29778 (CVE-2020-15801).

* bpo-41162: Audit hooks are now cleared later during finalization to
  avoid missing events.

* bpo-29778: Ensure "python3.dll" is loaded from correct locations
  when Python is embedded (CVE-2020-15523).

* bpo-41004: The __hash__() methods of  ipaddress.IPv4Interface and
  ipaddress.IPv6Interface incorrectly generated constant hash values
  of 32 and 128 respectively. This resulted in always causing hash
  collisions. The fix uses hash() to generate hash values for the
  tuple of (address, mask length, network address).

* bpo-39603: Prevent http header injection by rejecting control
  characters in http.client.putrequest(…).


Core and Builtins
-----------------

* bpo-41909: Fixed stack overflow in "issubclass()" and "isinstance()"
  when getting the "__bases__" attribute leads to infinite recursion.

* bpo-41922: Speed up calls to "reversed()" by using the **PEP 590**
  "vectorcall" calling convention. Patch by Dong-hee Na.

* bpo-41873: Calls to "float()" are now faster due to the "vectorcall"
  calling convention. Patch by Dennis Sweeney.

* bpo-41870: Speed up calls to "bool()" by using the **PEP 590**
  "vectorcall" calling convention. Patch by Dong-hee Na.

* bpo-1635741: Port the "_bisect" module to the multi-phase
  initialization API (**PEP 489**).

* bpo-39934: Correctly count control blocks in ‘except’ in compiler.
  Ensures that a syntax error, rather a fatal error, occurs for deeply
  nested, named exception handlers.

* bpo-41780: Fix "__dir__()" of "types.GenericAlias". Patch by Batuhan
  Taskaya.

* bpo-1635741: Port the "_lsprof" extension module to multi-phase
  initialization (**PEP 489**).

* bpo-1635741: Port the "cmath" extension module to multi-phase
  initialization (**PEP 489**).

* bpo-1635741: Port the "_scproxy" extension module to multi-phase
  initialization (**PEP 489**).

* bpo-1635741: Port the "termios" extension module to multi-phase
  initialization (**PEP 489**).

* bpo-1635741: Convert the "_sha256" extension module types to heap
  types.

* bpo-41690: Fix a possible stack overflow in the parser when parsing
  functions and classes with a huge amount of arguments. Patch by
  Pablo Galindo.

* bpo-1635741: Port the "_overlapped" extension module to multi-phase
  initialization (**PEP 489**).

* bpo-1635741: Port the "_curses_panel" extension module to multi-
  phase initialization (**PEP 489**).

* bpo-1635741: Port the "_opcode" extension module to multi-phase
  initialization (**PEP 489**).

* bpo-41681: Fixes the wrong error description in the error raised by
  using 2 "," in format string in f-string and "str.format()".

* bpo-41675: The implementation of "signal.siginterrupt()" now uses
  "sigaction()" (if it is available in the system) instead of the
  deprecated "siginterrupt()". Patch by Pablo Galindo.

* bpo-41670: Prevent line trace being skipped on platforms not
  compiled with "USE_COMPUTED_GOTOS". Fixes issue where some lines
  nested within a try-except block were not being traced on Windows.

* bpo-41654: Fix a crash that occurred when destroying subclasses of
  "MemoryError". Patch by Pablo Galindo.

* bpo-1635741: Port the "zlib" extension module to multi-phase
  initialization (**PEP 489**).

* bpo-41631: The "_ast" module uses again a global state. Using a
  module state per module instance is causing subtle practical
  problems. For example, the Mercurial project replaces the
  "__import__()" function to implement lazy import, whereas Python
  expected that "import _ast" always return a fully initialized "_ast"
  module.

* bpo-40077: Convert "_operator" to use "PyType_FromSpec()".

* bpo-1653741: Port "_sha3" to multi-phase init.  Convert static types
  to heap types.

* bpo-1635741: Port the "_blake2" extension module to the multi-phase
  initialization API (**PEP 489**).

* bpo-41533: Free the stack allocated in "va_build_stack" if
  "do_mkstack" fails and the stack is not a "small_stack".

* bpo-41531: Fix a bug that was dropping keys when compiling dict
  literals with more than 0xFFFF elements. Patch by Pablo Galindo.

* bpo-41525: The output of "python --help" contains now only ASCII
  characters.

* bpo-1635741: Port the "_sha1", "_sha512", and "_md5" extension
  modules to multi-phase initialization API (**PEP 489**).

* bpo-41431: Optimize "dict_merge()" for copying dict (e.g. "dict(d)"
  and "{}.update(d)").

* bpo-41428: Implement PEP 604. This supports (int | str) etc. in
  place of Union[str, int].

* bpo-41340: Removed fallback implementation for "strdup".

* bpo-38156: Handle interrupts that come after EOF correctly in
  "PyOS_StdioReadline".

* bpo-41342: "round()" with integer argument is now faster (9–60%).

* bpo-41334: Constructors "str()", "bytes()" and "bytearray()" are now
  faster (around 30–40% for small objects).

* bpo-41295: Resolve a regression in CPython 3.8.4 where defining
  “__setattr__” in a multi-inheritance setup and calling up the
  hierarchy chain could fail if builtins/extension types were involved
  in the base types.

* bpo-41323: Bytecode optimizations are performed directly on the
  control flow graph. This will result in slightly more compact code
  objects in some circumstances.

* bpo-41247: Always cache the running loop holder when running
  "asyncio.set_running_loop".

* bpo-41252: Fix incorrect refcounting in _ssl.c’s
  "_servername_callback()".

* bpo-1635741: Port "multiprocessing" to multi-phase initialization

* bpo-1635741: Port "winapi" to multiphase initialization

* bpo-41215: Use non-NULL default values in the PEG parser keyword
  list to overcome a bug that was preventing Python from being
  properly compiled when using the XLC compiler. Patch by Pablo
  Galindo.

* bpo-41218: Python 3.8.3 had a regression where compiling with
  ast.PyCF_ALLOW_TOP_LEVEL_AWAIT would aggressively mark list
  comprehension with CO_COROUTINE. Now only list comprehension making
  use of async/await will tagged as so.

* bpo-1635741: Port "faulthandler" to multiphase initialization.

* bpo-1635741: Port "sha256" to multiphase initialization

* bpo-41175: Guard against a NULL pointer dereference within
  bytearrayobject triggered by the "bytearray() + bytearray()"
  operation.

* bpo-41100: add arm64 to the allowable Mac OS arches in mpdecimal.h

* bpo-41094: Fix decoding errors with audit when open files with non-
  ASCII names on non-UTF-8 locale.

* bpo-39960: The “hackcheck” that prevents sneaking around a type’s
  __setattr__() by calling the superclass method was rewritten to
  allow C implemented heap types.

* bpo-41084: Prefix the error message with ‘f-string: ‘, when parsing
  an f-string expression which throws a "SyntaxError".

* bpo-40521: Empty frozensets are no longer singletons.

* bpo-41076: Pre-feed the parser with the location of the f-string
  expression, not the f-string itself, which allows us to skip the
  shifting of the AST node locations after the parsing is completed.

* bpo-41056: Fixes a reference to deallocated stack space during
  startup when constructing sys.path involving a relative symlink when
  code was supplied via -c.  (discovered via Coverity)

* bpo-41061: Fix incorrect expressions and asserts in hashtable code
  and tests.

* bpo-41052: Opt out serialization/deserialization for _random.Random

* bpo-40939: Rename "PyPegen*" functions to "PyParser*", so that we
  can remove the old set of "PyParser*" functions that were using the
  old parser, but keep everything backwards-compatible.

* bpo-35975: Stefan Behnel reported that cf_feature_version is used
  even when PyCF_ONLY_AST is not set. This is against the intention
  and against the documented behavior, so it’s been fixed.

* bpo-40939: Remove the remaining files from the old parser and the
  "symbol" module.

* bpo-40077: Convert "_bz2" to use "PyType_FromSpec()".

* bpo-41006: The "encodings.latin_1" module is no longer imported at
  startup. Now it is only imported when it is the filesystem encoding
  or the stdio encoding.

* bpo-40636: "zip()" now supports **PEP 618**’s "strict" parameter,
  which raises a "ValueError" if the arguments are exhausted at
  different lengths. Patch by Brandt Bucher.

* bpo-1635741: Port "_gdbm" to multiphase initialization.

* bpo-40985: Fix a bug that caused the "SyntaxError" text to be empty
  when a file ends with a line ending in a line continuation character
  (i.e. backslash). The error text should contain the text of the last
  line.

* bpo-40958: Fix a possible buffer overflow in the PEG parser when
  gathering information for emitting syntax errors. Patch by Pablo
  Galindo.

* bpo-1635741: Port "_dbm" to multiphase initialization.

* bpo-40957: Fix refleak in _Py_fopen_obj() when PySys_Audit() fails

* bpo-40950: Add a state to the "nis" module (**PEP 3121**) and apply
  the multiphase initialization. Patch by Dong-hee Na.

* bpo-40947: The Python Path Configuration now takes
  "PyConfig.platlibdir" in account.

* bpo-40939: Remove the old parser, the "parser" module and all
  associated support code, command-line options and environment
  variables. Patch by Pablo Galindo.

* bpo-40847: Fix a bug where a line with only a line continuation
  character is not considered a blank line at tokenizer level. In such
  cases, more than a single "NEWLINE" token was emitted. The old
  parser was working around the issue, but the new parser threw a
  "SyntaxError" for valid input due to this. For example, an empty
  line following a line continuation character was interpreted as a
  "SyntaxError".

* bpo-40890: Each dictionary view now has a "mapping" attribute that
  provides a "types.MappingProxyType" wrapping the original
  dictionary.  Patch contributed by Dennis Sweeney.

* bpo-40889: Improved the performance of symmetric difference
  operations on dictionary item views.  Patch by Dennis Sweeney.

* bpo-40904: Fix possible segfault in the new PEG parser when parsing
  f-string containing yield statements with no value ("f"{yield}"").
  Patch by Pablo Galindo

* bpo-40903: Fixed a possible segfault in the new PEG parser when
  producing error messages for invalid assignments of the form "p=p=".
  Patch by Pablo Galindo

* bpo-40880: Fix invalid memory read in the new parser when checking
  newlines in string literals. Patch by Pablo Galindo.

* bpo-40883: Fix memory leak in when parsing f-strings in the new
  parser. Patch by Pablo Galindo

* bpo-40870: Raise "ValueError" when validating custom AST’s where the
  constants "True", "False" and "None" are used within a "ast.Name"
  node.

* bpo-40854: Allow overriding "sys.platlibdir" via a new
  "PYTHONPLATLIBDIR" environment variable.

* bpo-40826: Fix GIL usage in "PyOS_Readline()": lock the GIL to set
  an exception and pass the Python thread state when checking if there
  is a pending signal.

* bpo-1635741: Port "fcntl" to multiphase initialization.

* bpo-19468: Delete unnecessary instance check in importlib.reload().
  Patch by Furkan Önder.

* bpo-40824: Unexpected errors in calling the "__iter__" method are no
  longer masked by "TypeError" in the "in" operator and functions
  "contains()", "indexOf()" and "countOf()" of the "operator" module.

* bpo-40792: Attributes "start", "stop" and "step" of the "range"
  object now always has exact type "int".  Previously, they could have
  been an instance of a subclass of "int".

* bpo-40780: Fix a corner case where g-style string formatting of a
  float failed to remove trailing zeros.

* bpo-38964: When there’s a "SyntaxError" in the expression part of an
  fstring, the filename attribute of the "SyntaxError" gets correctly
  set to the name of the file the fstring resides in.

* bpo-40750: Support the “-d” debug flag in the new PEG parser. Patch
  by Pablo Galindo

* bpo-40217: Instances of types created with
  "PyType_FromSpecWithBases()" will no longer automatically visit
  their class object when traversing references in the garbage
  collector. The user is expected to manually visit the object’s
  class. Patch by Pablo Galindo.

* bpo-39573: "Py_TYPE()" is changed to the inline static function.
  Patch by Dong-hee Na.

* bpo-40696: Fix a hang that can arise after "generator.throw()" due
  to a cycle in the exception context chain.

* bpo-40521: Each interpreter now its has own free lists, singletons
  and caches:

  * Free lists: float, tuple, list, dict, frame, context, asynchronous
    generator, MemoryError.

  * Singletons: empty tuple, empty bytes string, empty Unicode string,
    single byte character, single Unicode (latin1) character.

  * Slice cache.

  They are no longer shared by all interpreters.

* bpo-40679: Certain "TypeError" messages about missing or extra
  arguments now include the function’s *qualified name*.  Patch by
  Dennis Sweeney.

* bpo-29590: Make the stack trace correct after calling
  "generator.throw()" on a generator that has yielded from a "yield
  from".

* bpo-4022: Improve performance of generators by not raising internal
  StopIteration.

* bpo-1635741: Port "mmap" to multiphase initialization.

* bpo-1635741: Port "_lzma" to multiphase initialization.

* bpo-37999: Builtin and extension functions that take integer
  arguments no longer accept "Decimal"s, "Fraction"s and other objects
  that can be converted to integers only with a loss (e.g. that have
  the "__int__()" method but do not have the "__index__()" method).

* bpo-29882: Add "int.bit_count()", counting the number of ones in the
  binary representation of an integer. Patch by Niklas Fiekas.

* bpo-36982: Use ncurses extended color functions when available to
  support terminals with 256 colors, and add the new function
  "curses.has_extended_color_support()" to indicate whether extended
  color support is provided by the underlying ncurses library.

* bpo-19569: Add the private macros "_Py_COMP_DIAG_PUSH",
  "_Py_COMP_DIAG_IGNORE_DEPR_DECLS", and "_Py_COMP_DIAG_POP".

* bpo-26680: The int type now supports the x.is_integer() method for
  compatibility with float.


Library
-------

* bpo-41900: C14N 2.0 serialisation in xml.etree.ElementTree failed
  for unprefixed attributes when a default namespace was defined.

* bpo-41887: Strip leading spaces and tabs on "ast.literal_eval()".
  Also document stripping of spaces and tabs for "eval()".

* bpo-41773: Note in documentation that "random.choices()" doesn’t
  support non-finite weights, raise "ValueError" when given non-finite
  weights.

* bpo-41840: Fix a bug in the "symtable" module that was causing
  module-scope global variables to not be reported as both local and
  global. Patch by Pablo Galindo.

* bpo-41842: Add "codecs.unregister()" function to unregister a codec
  search function.

* bpo-40564: In "zipfile.Path", mutate the passed ZipFile object type
  instead of making a copy. Prevents issues when both the local copy
  and the caller’s copy attempt to close the same file handle.

* bpo-40670: More reliable validation of statements in "timeit.Timer".
  It now accepts “empty” statements (only whitespaces and comments)
  and rejects misindentent statements.

* bpo-41833: The "threading.Thread" constructor now uses the target
  name if the *target* argument is specified but the *name* argument
  is omitted.

* bpo-41817: fix "tkinter.EventType" Enum so all members are strings,
  and none are tuples

* bpo-41810: "types.EllipsisType", "types.NotImplementedType" and
  "types.NoneType" have been reintroduced, providing a new set of
  types readily interpretable by static type checkers.

* bpo-41815: Fix SQLite3 segfault when backing up closed database.
  Patch contributed by Peter David McCormick.

* bpo-41816: StrEnum added: it ensures that all members are already
  strings or string candidates

* bpo-41517: fix bug allowing Enums to be extended via multiple
  inheritance

* bpo-39587: use the correct mix-in data type when constructing Enums

* bpo-41792: Add is_typeddict function to typing.py to check if a type
  is a TypedDict class

  Previously there was no way to check that without using private API.
  See the "relevant issue in python/typing"

* bpo-41789: Honor "object" overrides in "Enum" class creation
  (specifically, "__str__", "__repr__", "__format__", and
  "__reduce_ex__").

* bpo-32218: "enum.Flag" and "enum.IntFlag" members are now iterable

* bpo-39651: Fix a race condition in the "call_soon_threadsafe()"
  method of "asyncio.ProactorEventLoop": do nothing if the self-pipe
  socket has been closed.

* bpo-1635741: Port the "mashal" extension module to the multi-phase
  initialization API (**PEP 489**).

* bpo-1635741: Port the "_string" extension module to the multi-phase
  initialization API (**PEP 489**).

* bpo-41732: Added an *iterator* to "memoryview".

* bpo-41720: Fixed "turtle.Vec2D.__rmul__()" for arguments which are
  not int or float.

* bpo-41696: Fix handling of debug mode in "asyncio.run()". This
  allows setting "PYTHONASYNCIODEBUG" or "-X dev" to enable asyncio
  debug mode when using "asyncio.run()".

* bpo-41687: Fix implementation of sendfile to be compatible with
  Solaris.

* bpo-41662: No longer override exceptions raised in "__len__()" of a
  sequence of parameters in "sqlite3" with "ProgrammingError".

* bpo-39010: Restarting a "ProactorEventLoop" on Windows no longer
  logs spurious "ConnectionResetErrors".

* bpo-41638: "ProgrammingError" message for absent parameter in
  "sqlite3" contains now the name of the parameter instead of its
  index when parameters are supplied as a dict.

* bpo-41662: Fixed crash when mutate list of parameters during
  iteration in "sqlite3".

* bpo-41513: Improved the accuracy of math.hypot().  Internally, each
  step is computed with extra precision so that the result is now
  almost always correctly rounded.

* bpo-41609: The pdb whatis command correctly reports instance methods
  as ‘Method’ rather than ‘Function’.

* bpo-39994: Fixed pprint’s handling of dict subclasses that override
  __repr__.

* bpo-32751: When cancelling the task due to a timeout,
  "asyncio.wait_for()" will now wait until the cancellation is
  complete also in the case when *timeout* is <= 0, like it does with
  positive timeouts.

* bpo-37658: "asyncio.wait_for()" now properly handles races between
  cancellation of itself and the completion of the wrapped awaitable.

* bpo-40782: Change the method
  asyncio.AbstractEventLoop.run_in_executor to not be a coroutine.

* bpo-41520: Fix "codeop" regression that prevented turning compile
  warnings into errors.

* bpo-41528: turtle uses math module functions to convert degrees to
  radians and vice versa and to calculate vector norm

* bpo-41513: Minor algorithmic improvement to math.hypot() and
  math.dist() giving small gains in speed and accuracy.

* bpo-41503: Fixed a race between setTarget and flush in
  logging.handlers.MemoryHandler.

* bpo-41497: Fix potential UnicodeDecodeError in dis module.

* bpo-41467: On Windows, fix asyncio "recv_into()" return value when
  the socket/pipe is closed ("BrokenPipeError"): return "0" rather
  than an empty byte string ("b''").

* bpo-41425: Make tkinter doc example runnable.

* bpo-41421: Make an algebraic simplification to
  random.paretovariate().  It now is slightly less subject to round-
  off error and is slightly faster. Inputs that used to cause
  ZeroDivisionError now cause an OverflowError instead.

* bpo-41440: Add "os.cpu_count()" support for VxWorks RTOS.

* bpo-41316: Fix the "tarfile" module to write only basename of TAR
  file to GZIP compression header.

* bpo-41384: Raise TclError instead of TypeError when an unknown
  option is passed to tkinter.OptionMenu.

* bpo-41317: Use add_done_callback() in asyncio.loop.sock_accept() to
  unsubscribe reader early on cancellation.

* bpo-41364: Reduce import overhead of "uuid".

* bpo-35328: Set the environment variable "VIRTUAL_ENV_PROMPT" at
  "venv" activation.

* bpo-41341: Recursive evaluation of "typing.ForwardRef" in
  "get_type_hints".

* bpo-41344: Prevent creating "shared_memory.SharedMemory" objects
  with "size=0".

* bpo-41333: "collections.OrderedDict.pop()" is now 2 times faster.

* bpo-41288: Unpickling invalid NEWOBJ_EX opcode with the C
  implementation raises now UnpicklingError instead of crashing.

* bpo-39017: Avoid infinite loop when reading specially crafted TAR
  files using the tarfile module (CVE-2019-20907).

* bpo-41273: Speed up any transport using "_ProactorReadPipeTransport"
  by calling "recv_into" instead of "recv", thus not creating a new
  buffer for each "recv" call in the transport’s read loop.

* bpo-41235: Fix the error handling in
  "ssl.SSLContext.load_dh_params()".

* bpo-41207: In distutils.spawn, restore expectation that
  DistutilsExecError is raised when the command is not found.

* bpo-29727: Register "array.array" as a "MutableSequence". Patch by
  Pablo Galindo.

* bpo-39168: Remove the "__new__" method of "typing.Generic".

* bpo-41194: Fix a crash in the "_ast" module: it can no longer be
  loaded more than once. It now uses a global state rather than a
  module state.

* bpo-41195: Add read-only ssl.SSLContext.security_level attribute to
  retrieve the context’s security level.

* bpo-41193: The "write_history()" atexit function of the readline
  completer now ignores any "OSError" to ignore error if the
  filesystem is read-only, instead of only ignoring
  "FileNotFoundError" and "PermissionError".

* bpo-41182: selector: use DefaultSelector based upon implementation

* bpo-41161: The decimal module now requires libmpdec-2.5.0. Users of
  –with-system-libmpdec should update their system library.

* bpo-40874: The decimal module now requires libmpdec-2.5.0.

* bpo-41138: Fixed the "trace" module CLI for Python source files with
  non-UTF-8 encoding.

* bpo-31082: Use the term “iterable” in the docstring for
  "functools.reduce()".

* bpo-40521: Remove freelist from collections.deque().

* bpo-31938: Fix default-value signatures of several functions in the
  "select" module - by Anthony Sottile.

* bpo-41068: Fixed reading files with non-ASCII names from ZIP archive
  directly after writing them.

* bpo-41058: "pdb.find_function()" now correctly determines the source
  file encoding.

* bpo-41056: Invalid file descriptor values are now prevented from
  being passed to os.fpathconf. (discovered by Coverity)

* bpo-41056: Fix a NULL pointer dereference within the ssl module
  during a MemoryError in the keylog callback. (discovered by
  Coverity)

* bpo-41056: Fixed an instance where a MemoryError within the zoneinfo
  module might not be reported or not reported at its source. (found
  by Coverity)

* bpo-41048: "mimetypes.read_mime_types()" function reads the rule
  file using UTF-8 encoding, not the locale encoding. Patch by
  Srinivas Reddy Thatiparthy.

* bpo-41043: Fixed the use of "glob()" in the stdlib: literal part of
  the path is now always correctly escaped.

* bpo-41025: Fixed an issue preventing the C implementation of
  "zoneinfo.ZoneInfo" from being subclassed.

* bpo-35018: Add the "xml.sax.handler.LexicalHandler" class that is
  present in other SAX XML implementations.

* bpo-41002: Improve performance of HTTPResponse.read with a given
  amount. Patch by Bruce Merry.

* bpo-40448: "ensurepip" now disables the use of "pip" cache when
  installing the bundled versions of "pip" and "setuptools".  Patch by
  Krzysztof Konopko.

* bpo-40967: Removed "asyncio.Task.current_task()" and
  "asyncio.Task.all_tasks()". Patch contributed by Rémi Lapeyre.

* bpo-40924: Ensure "importlib.resources.path" returns an extant path
  for the SourceFileLoader’s resource reader. Avoids the regression
  identified in master while a long-term solution is devised.

* bpo-40955: Fix a minor memory leak in "subprocess" module when
  extra_groups was specified.

* bpo-40855: The standard deviation and variance functions in the
  statistics module were ignoring their mu and xbar arguments.

* bpo-40939: Use the new PEG parser when generating the stdlib
  "keyword" module.

* bpo-23427: Add "sys.orig_argv" attribute: the list of the original
  command line arguments passed to the Python executable.

* bpo-33689: Ignore empty or whitespace-only lines in .pth files. This
  matches the documentated behavior. Before, empty lines caused the
  site-packages dir to appear multiple times in sys.path. By Ido
  Michael, contributors Malcolm Smith and Tal Einat.

* bpo-40884: Added a "defaults" parameter to "logging.Formatter", to
  allow specifying default values for custom fields. Patch by Asaf
  Alon and Bar Harel.

* bpo-40876: Clarify error message in the "csv" module.

* bpo-39791: Refresh importlib.metadata from importlib_metadata 1.6.1.

* bpo-40807: Stop codeop._maybe_compile, used by
  code.InteractiveInterpreter (and IDLE). from emitting each warning
  three times.

* bpo-32604: Fix reference leak in the "select" module when the module
  is imported in a subinterpreter.

* bpo-39791: Built-in loaders (SourceFileLoader and ZipImporter) now
  supply "TraversableResources" implementations for "ResourceReader",
  and the fallback function has been removed.

* bpo-39314: "rlcompleter.Completer" and the standard Python shell now
  close the parenthesis for functions that take no arguments. Patch
  contributed by Rémi Lapeyre.

* bpo-17005: The topological sort functionality that was introduced
  initially in the "functools" module has been moved to a new
  "graphlib" module to better accommodate the new tools and keep the
  original scope of the "functools" module. Patch by Pablo Galindo

* bpo-40834: Fix truncate when sending str object
  with_xxsubinterpreters.channel_send.

* bpo-40755: Add rich comparisons to collections.Counter().

* bpo-26407: Unexpected errors in calling the "__iter__" method are no
  longer masked by "TypeError" in "csv.reader()",
  "csv.writer.writerow()" and "csv.writer.writerows()".

* bpo-39384: Fixed email.contentmanager to allow set_content() to set
  a null string.

* bpo-40744: The "sqlite3" module uses SQLite API functions that
  require SQLite v3.7.3 or higher.  This patch removes support for
  older SQLite versions, and explicitly requires SQLite 3.7.3 both at
  build, compile and runtime.  Patch by Sergey Fedoseev and Erlend E.
  Aasland.

* bpo-40777: Initialize PyDateTime_IsoCalendarDateType.tp_base at run-
  time to avoid errors on some compilers.

* bpo-38488: Update ensurepip to install pip 20.1.1 and setuptools
  47.1.0.

* bpo-40792: The result of "operator.index()" now always has exact
  type "int". Previously, the result could have been an instance of a
  subclass of "int".

* bpo-40767: "webbrowser" now properly finds the default browser in
  pure Wayland systems by checking the WAYLAND_DISPLAY environment
  variable. Patch contributed by Jérémy Attali.

* bpo-40791: "hashlib.compare_digest()" uses OpenSSL’s
  "CRYPTO_memcmp()" function when OpenSSL is available.

* bpo-40795: "ctypes" module: If ctypes fails to convert the result of
  a callback or if a ctypes callback function raises an exception,
  sys.unraisablehook is now called with an exception set. Previously,
  the error was logged into stderr by "PyErr_Print()".

* bpo-16995: Add "base64.b32hexencode()" and "base64.b32hexdecode()"
  to support the Base32 Encoding with Extended Hex Alphabet.

* bpo-30008: Fix "ssl" code to be compatible with OpenSSL 1.1.x builds
  that use "no-deprecated" and "--api=1.1.0".

* bpo-30064: Fix asyncio "loop.sock_*" race condition issue

* bpo-40759: Deprecate the "symbol" module.

* bpo-40756: The second argument (extra) of "LoggerAdapter.__init__"
  now defaults to None.

* bpo-37129: Add a new "os.RWF_APPEND" flag for "os.pwritev()".

* bpo-40737: Fix possible reference leak for "sqlite3" initialization.

* bpo-40726: Handle cases where the "end_lineno" is "None" on
  "ast.increment_lineno()".

* bpo-40698: "distutils" upload creates SHA2-256 and Blake2b-256
  digests. MD5 digests is skipped if platform blocks MD5.

* bpo-40695: "hashlib" no longer falls back to builtin hash
  implementations when OpenSSL provides a hash digest and the
  algorithm is blocked by security policy.

* bpo-9216: func:"hashlib.new" passed "usedforsecurity" to OpenSSL EVP
  constructor "_hashlib.new()". test_hashlib and test_smtplib handle
  strict security policy better.

* bpo-40614: "ast.parse()" will not parse self documenting expressions
  in f-strings when passed "feature_version" is less than "(3, 8)".

* bpo-40626: Add h5 file extension as MIME Type application/x-hdf5, as
  per HDF Group recommendation for HDF5 formatted data files. Patch
  contributed by Mark Schwab.

* bpo-25920: On macOS, when building Python for macOS 10.4 and older,
  which wasn’t the case for python.org macOS installer,
  "socket.getaddrinfo()" no longer uses an internal lock to prevent
  race conditions when calling "getaddrinfo()" which is thread-safe
  since macOS 10.5. Python 3.9 requires macOS 10.6 or newer. The
  internal lock caused random hang on fork when another thread was
  calling "socket.getaddrinfo()". The lock was also used on FreeBSD
  older than 5.3, OpenBSD older than 201311 and NetBSD older than 4.

* bpo-40671: Prepare "_hashlib" for **PEP 489** and use
  "PyModule_AddType()".

* bpo-32309: Added a new *coroutine* "asyncio.to_thread()". It is
  mainly used for running IO-bound functions in a separate thread to
  avoid blocking the event loop, and essentially works as a high-level
  version of "run_in_executor()" that can directly take keyword
  arguments.

* bpo-36543: Restored the deprecated "xml.etree.cElementTree" module.

* bpo-40611: "MAP_POPULATE" constant has now been added to the list of
  exported "mmap" module flags.

* bpo-39881: PEP 554 for use in the test suite. (Patch By Joannah
  Nanjekye)

* bpo-13097: "ctypes" now raises an "ArgumentError" when a callback is
  invoked with more than 1024 arguments.

* bpo-39385: A new test assertion context-manager,
  "unittest.assertNoLogs()" will ensure a given block of code emits no
  log messages using the logging module. Contributed by Kit Yan Choi.

* bpo-23082: Updated the error message and docs of
  PurePath.relative_to() to better reflect the function behaviour.

* bpo-40318: Use SQLite3 trace v2 API, if it is available.

* bpo-40105: ZipFile truncates files to avoid corruption when a
  shorter comment is provided in append (“a”) mode. Patch by Jan
  Mazur.

* bpo-40084: Fix "Enum.__dir__": dir(Enum.member) now includes
  attributes as well as methods.

* bpo-31122: ssl.wrap_socket() now raises ssl.SSLEOFError rather than
  OSError when peer closes connection during TLS negotiation

* bpo-39728: fix default "_missing_" so a duplicate "ValueError" is
  not set as the "__context__" of the original "ValueError"

* bpo-39244: Fixed "multiprocessing.context.get_all_start_methods" to
  properly return the default method first on macOS.

* bpo-39040: Fix parsing of invalid mime headers parameters by
  collapsing whitespace between encoded words in a bare-quote-string.

* bpo-38731: Add "--quiet" option to command-line interface of
  "py_compile". Patch by Gregory Schevchenko.

* bpo-35714: "struct.error" is now raised if there is a null character
  in a "struct" format string.

* bpo-38144: Added the *root_dir* and *dir_fd* parameters in
  "glob.glob()".

* bpo-26543: Fix "IMAP4.noop()" when debug mode is enabled (ex:
  "imaplib.Debug = 3").

* bpo-12178: "csv.writer()" now correctly escapes *escapechar* when
  input contains *escapechar*.  Patch by Catalin Iacob, Berker Peksag,
  and Itay Elbirt.

* bpo-36290: AST nodes are now raising "TypeError" on conflicting
  keyword arguments. Patch contributed by Rémi Lapeyre.

* bpo-33944: Added site.py site-packages tracing in verbose mode.

* bpo-35078: Refactor formatweekday, formatmonthname methods in
  LocaleHTMLCalendar and LocaleTextCalendar classes in calendar module
  to call the base class methods.This enables customizable CSS classes
  for LocaleHTMLCalendar. Patch by Srinivas Reddy Thatiparthy

* bpo-29620: "assertWarns()" no longer raises a "RuntimeException"
  when accessing a module’s "__warningregistry__" causes importation
  of a new module, or when a new module is imported in another thread.
  Patch by Kernc.

* bpo-31844: Remove "ParserBase.error()" method from the private and
  undocumented "_markupbase" module.  "html.parser.HTMLParser" is the
  only subclass of "ParserBase" and its "error()" implementation was
  deprecated in Python 3.4 and removed in Python 3.5.

* bpo-34226: Fix "cgi.parse_multipart" without content_length. Patch
  by Roger Duran

* bpo-33660: Fix pathlib.PosixPath to resolve a relative path located
  on the root directory properly.

* bpo-28557: Improve the error message for a misbehaving
  "rawio.readinto"

* bpo-26680: The d.is_integer() method is added to the Decimal type,
  for compatibility with other number types.

* bpo-26680: The x.is_integer() method is incorporated into the
  abstract types of the numeric tower, Real, Rational and Integral,
  with appropriate default implementations.


Documentation
-------------

* bpo-41428: Add documentation for **PEP 604** (Allow writing union
  types as "X | Y").

* bpo-41774: In Programming FAQ “Sequences (Tuples/Lists)” section,
  add “How do you remove multiple items from a list”.

* bpo-35293: Fix RemovedInSphinx40Warning when building the
  documentation. Patch by Dong-hee Na.

* bpo-37149: Change Shipman tkinter doc link from archive.org to
  TkDocs. (The doc has been removed from the NMT server.)  The new
  link responds much faster and includes a short explanatory note.

* bpo-41726: Update the refcounts info of "PyType_FromModuleAndSpec".

* bpo-41624: Fix the signature of "typing.Coroutine".

* bpo-40204: Enable Sphinx 3.2 "c_allow_pre_v3" option and disable
  "c_warn_on_allowed_pre_v3" option to make the documentation
  compatible with Sphinx 2 and Sphinx 3.

* bpo-41045: Add documentation for debug feature of f-strings.

* bpo-41314: Changed the release when "from __future__ import
  annotations" becomes the default from "4.0" to "3.10" (following a
  change in PEP 563).

* bpo-40979: Refactored typing.rst, arranging more than 70 classes,
  functions, and decorators into new sub-sections.

* bpo-40552: Fix in tutorial section 4.2. Code snippet is now correct.

* bpo-39883: Make code, examples, and recipes in the Python
  documentation be licensed under the more permissive BSD0 license in
  addition to the existing Python 2.0 license.

* bpo-37703: Updated Documentation to comprehensively elaborate on the
  behaviour of gather.cancel()


Tests
-----

* bpo-41939: Fix test_site.test_license_exists_at_url(): call
  "urllib.request.urlcleanup()" to reset the global
  "urllib.request._opener". Patch by Victor Stinner.

* bpo-41731: Make test_cmd_line_script pass with option ‘-vv’.

* bpo-41602: Add tests for SIGINT handling in the runpy module.

* bpo-41521: "test.support": Rename "blacklist" parameter of
  "check__all__()" to "not_exported".

* bpo-41477: Make ctypes optional in test_genericalias.

* bpo-41085: Fix integer overflow in the "array.array.index()" method
  on 64-bit Windows for index larger than "2**31".

* bpo-41069: "test.support.TESTFN" and the current directory for tests
  when run via "test.regrtest" contain now non-ascii characters if
  possible.

* bpo-38377: On Linux, skip tests using multiprocessing if the current
  user cannot create a file in "/dev/shm/" directory. Add the
  "skip_if_broken_multiprocessing_synchronize()" function to the
  "test.support" module.

* bpo-41009: Fix use of
  "support.require_{linux|mac|freebsd}_version()" decorators as class
  decorator.

* bpo-41003: Fix "test_copyreg" when "numpy" is installed:
  "test.pickletester" now saves/restores warnings filters when
  importing "numpy", to ignore filters installed by "numpy".

* bpo-40964: Disable remote "imaplib" tests, host cyrus.andrew.cmu.edu
  is blocking incoming connections.

* bpo-40927: Fix test_binhex when run twice: it now uses
  import_fresh_module() to ensure that it raises DeprecationWarning
  each time.

* bpo-17258: Skip some "multiprocessing" tests when MD5 hash digest is
  blocked.

* bpo-31904: Increase LOOPBACK_TIMEOUT to 10 for VxWorks RTOS.

* bpo-38169: Increase code coverage for SharedMemory and ShareableList

* bpo-34401: Make test_gdb properly run on HP-UX. Patch by Michael
  Osipov.


Build
-----

* bpo-38249: Update "Py_UNREACHABLE" to use __builtin_unreachable() if
  only the compiler is able to use it. Patch by Dong-hee Na.

* bpo-41617: Fix "pycore_bitutils.h" header file to support old clang
  versions: "__builtin_bswap16()" is not available in LLVM clang 3.0.

* bpo-40204: Pin Sphinx version to 2.3.1 in "Doc/Makefile".

* bpo-36020: The C99 functions "snprintf()" and "vsnprintf()" are now
  required to build Python.

* bpo-40684: "make install" now uses the "PLATLIBDIR" variable for the
  destination "lib-dynload/" directory when "./configure --with-
  platlibdir" is used.

* bpo-40683: Fixed an issue where the "zoneinfo" module and its tests
  were not included when Python is installed with "make".


Windows
-------

* bpo-41744: Fixes automatic import of props file when using the Nuget
  package.

* bpo-41627: The user site directory for 32-bit now includes a "-32"
  suffix to distinguish it from the 64-bit interpreter’s directory.

* bpo-41526: Fixed layout of final page of the installer by removing
  the special thanks to Mark Hammond (with his permission).

* bpo-41492: Fixes the description that appears in UAC prompts.

* bpo-40948: Improve post-install message to direct people to the “py”
  command.

* bpo-41412: The installer will now fail to install on Windows 7 and
  Windows 8. Further, the UCRT dependency is now always downloaded on
  demand.

* bpo-40741: Update Windows release to include SQLite 3.32.3.

* bpo-41142: "msilib" now supports creating CAB files with non-ASCII
  file path and adding files with non-ASCII file path to them.

* bpo-41074: Fixed support of non-ASCII names in functions
  "msilib.OpenDatabase()" and "msilib.init_database()" and non-ASCII
  SQL in method "msilib.Database.OpenView()".

* bpo-41039: Stable ABI redirection DLL (python3.dll) now uses
  "#pragma comment(linker)" for re-exporting.

* bpo-40164: Updates Windows OpenSSL to 1.1.1g

* bpo-39631: Changes the registered MIME type for ".py" files on
  Windows to "text/x-python" instead of "text/plain".

* bpo-40677: Manually define IO_REPARSE_TAG_APPEXECLINK in case some
  old Windows SDK doesn’t have it.

* bpo-37556: Extend py.exe help to mention overrides via venv,
  shebang, environmental variables & ini files.


macOS
-----

* bpo-41557: Update macOS installer to use SQLite 3.33.0.

* bpo-39580: Avoid opening Finder window if running installer from the
  command line. Patch contributed by Rick Heil.

* bpo-41100: Fix configure error when building on macOS 11. Note that
  the current Python release was released shortly after the first
  developer preview of macOS 11 (Big Sur); there are other known
  issues with building and running on the developer preview. Big Sur
  is expected to be fully supported in a future bugfix release of
  Python 3.8.x and with 3.9.0.

* bpo-40741: Update macOS installer to use SQLite 3.32.3.

* bpo-41005: fixed an XDG settings issue not allowing macos to open
  browser in webbrowser.py

* bpo-40741: Update macOS installer to use SQLite 3.32.2.


IDLE
----

* bpo-41775: Use ‘IDLE Shell’ as shell title

* bpo-35764: Rewrite the Calltips doc section.

* bpo-40181: In calltips, stop reminding that ‘/’ marks the end of
  positional-only arguments.

* bpo-41468: Improve IDLE run crash error message (which users should
  never see).

* bpo-41373: Save files loaded with no line ending, as when blank, or
  different line endings, by setting its line ending to the system
  default. Fix regression in 3.8.4 and 3.9.0b4.

* bpo-41300: Save files with non-ascii chars. Fix regression released
  in 3.9.0b4 and 3.8.4.

* bpo-37765: Add keywords to module name completion list.  Rewrite
  Completions section of IDLE doc.

* bpo-41152: The encoding of "stdin", "stdout" and "stderr" in IDLE is
  now always UTF-8.

* bpo-41144: Make Open Module open a special module such as os.path.

* bpo-39885: Make context menu Cut and Copy work again when right-
  clicking within a selection.

* bpo-40723: Make test_idle pass when run after import.


C API
-----

* bpo-41936: Removed undocumented macros "Py_ALLOW_RECURSION" and
  "Py_END_ALLOW_RECURSION" and the "recursion_critical" field of the
  "PyInterpreterState" structure.

* bpo-41692: The "PyUnicode_InternImmortal()" function is now
  deprecated and will be removed in Python 3.12: use
  "PyUnicode_InternInPlace()" instead. Patch by Victor Stinner.

* bpo-41842: Add "PyCodec_Unregister()" function to unregister a codec
  search function.

* bpo-41834: Remove the "_Py_CheckRecursionLimit" variable: it has
  been replaced by "ceval.recursion_limit" of the "PyInterpreterState"
  structure. Patch by Victor Stinner.

* bpo-41689: Types created with "PyType_FromSpec()" now make any
  signature in their "tp_doc" slot accessible from
  "__text_signature__".

* bpo-41524: Fix bug in PyOS_mystrnicmp and PyOS_mystricmp that
  incremented pointers beyond the end of a string.

* bpo-41324: Add a minimal decimal capsule API.  The API supports fast
  conversions between Decimals up to 38 digits and their triple
  representation as a C struct.

* bpo-30155: Add "PyDateTime_DATE_GET_TZINFO()" and
  "PyDateTime_TIME_GET_TZINFO()" macros for accessing the "tzinfo"
  attributes of "datetime.datetime" and "datetime.time" objects.

* bpo-40170: Revert "PyType_HasFeature()" change: it reads again
  directly the "PyTypeObject.tp_flags" member when the limited C API
  is not used, rather than always calling "PyType_GetFlags()" which
  hides implementation details.

* bpo-41123: Remove "PyUnicode_AsUnicodeCopy".

* bpo-41123: Removed "PyLong_FromUnicode()".

* bpo-41123: Removed "PyUnicode_GetMax()".

* bpo-41123: Removed "Py_UNICODE_str*" functions manipulating
  "Py_UNICODE*" strings.

* bpo-41103: "PyObject_AsCharBuffer()", "PyObject_AsReadBuffer()",
  "PyObject_CheckReadBuffer()", and "PyObject_AsWriteBuffer()" are
  removed. Please migrate to new buffer protocol;
  "PyObject_GetBuffer()" and "PyBuffer_Release()".

* bpo-36346: Raises DeprecationWarning for
  "PyUnicode_FromUnicode(NULL, size)" and
  "PyUnicode_FromStringAndSize(NULL, size)" with "size > 0".

* bpo-36346: Mark "Py_UNICODE_COPY", "Py_UNICODE_FILL",
  "PyUnicode_WSTR_LENGTH", "PyUnicode_FromUnicode",
  "PyUnicode_AsUnicode", and "PyUnicode_AsUnicodeAndSize" as
  deprecated in C. Remove "Py_UNICODE_MATCH" which was deprecated and
  broken since Python 3.3.

* bpo-40989: The "PyObject_INIT()" and "PyObject_INIT_VAR()" macros
  become aliases to, respectively, "PyObject_Init()" and
  "PyObject_InitVar()" functions.

* bpo-36020: On Windows, "#include "pyerrors.h"" no longer defines
  "snprintf" and "vsnprintf" macros.

* bpo-40943: The "PY_SSIZE_T_CLEAN" macro must now be defined to use
  "PyArg_ParseTuple()" and "Py_BuildValue()" formats which use "#":
  "es#", "et#", "s#", "u#", "y#", "z#", "U#" and "Z#". See Parsing
  arguments and building values and the **PEP 353**.

* bpo-40910: Export explicitly the "Py_GetArgcArgv()" function to the
  C API and document the function. Previously, it was exported
  implicitly which no longer works since Python is built with
  "-fvisibility=hidden".

* bpo-40724: Allow defining buffer slots in type specs.

* bpo-40679: Fix a "_PyEval_EvalCode()" crash if *qualname* argument
  is NULL.

* bpo-40839: Calling "PyDict_GetItem()" without *GIL* held had been
  allowed for historical reason. It is no longer allowed.

* bpo-40826: "PyOS_InterruptOccurred()" now fails with a fatal error
  if it is called with the GIL released.

* bpo-40792: The result of "PyNumber_Index()" now always has exact
  type "int". Previously, the result could have been an instance of a
  subclass of "int".

* bpo-39573: Convert "Py_REFCNT()" and "Py_SIZE()" macros to static
  inline functions. They cannot be used as l-value anymore: use
  "Py_SET_REFCNT()" and "Py_SET_SIZE()" to set an object reference
  count and size. This change is backward incompatible on purpose, to
  prepare the C API for an opaque "PyObject" structure.

* bpo-40703: The PyType_FromSpec*() functions no longer overwrite the
  type’s “__module__” attribute if it is set via “Py_tp_members” or
  “Py_tp_getset”.

* bpo-39583: Remove superfluous “extern C” declarations from
  "Include/cpython/*.h".


Python 3.9.0 beta 1
===================

*Release date: 2020-05-19*


Security
--------

* bpo-40501: "uuid" no longer uses "ctypes" to load "libuuid" or
  "rpcrt4.dll" at runtime.


Core and Builtins
-----------------

* bpo-40663: Correctly generate annotations where parentheses are
  omitted but required (e.g: "Type[(str, int, *other))]".

* bpo-40596: Fixed "str.isidentifier()" for non-canonicalized strings
  containing non-BMP characters on Windows.

* bpo-40593: Improved syntax errors for invalid characters in source
  code.

* bpo-40585: Fixed a bug when using "codeop.compile_command()" that
  was causing exceptions to be swallowed with the new parser. Patch by
  Pablo Galindo

* bpo-40566: Apply **PEP 573** to "abc".

* bpo-40502: Initialize "n->n_col_offset". (Patch by Joannah Nanjekye)

* bpo-40527: Fix command line argument parsing: no longer write errors
  multiple times into stderr.

* bpo-1635741: Port "errno" to multiphase initialization (**PEP
  489**).

* bpo-40523: Add pass-throughs for "hash()" and "reversed()" to
  "weakref.proxy" objects. Patch by Pablo Galindo.

* bpo-1635741: Port "syslog" to multiphase initialization (**PEP
  489**).

* bpo-40246: Reporting a specialised error message for invalid string
  prefixes, which was introduced in bpo-40246, is being reverted due
  to backwards compatibility concerns for strings that immediately
  follow a reserved keyword without whitespace between them.
  Constructs like "bg="#d00" if clear else"#fca"" were failing to
  parse, which is not an acceptable breakage on such short notice.

* bpo-40417: Fix imp module deprecation warning when
  PyImport_ReloadModule is called. Patch by Robert Rouhani.

* bpo-40408: Fixed support of nested type variables in GenericAlias
  (e.g. "list[list[T]]").

* bpo-1635741: Port _stat module to multiphase initialization (**PEP
  489**).

* bpo-29587: Enable implicit exception chaining when calling
  "generator.throw()".

* bpo-40328: Add tools for generating mappings headers for CJKCodecs.

* bpo-40228: Setting frame.f_lineno is now robust w.r.t. changes in
  the source-to-bytecode compiler

* bpo-38880: Added the ability to list interpreters associated with
  channel ends in the internal subinterpreters module.

* bpo-37986: Improve performance of "PyLong_FromDouble()" for values
  that fit into "long".


Library
-------

* bpo-40662: Fixed "ast.get_source_segment()" for ast nodes that have
  incomplete location information. Patch by Irit Katriel.

* bpo-40665: Convert "bisect" to use Argument Clinic.

* bpo-40536: Added the "available_timezones()" function to the
  "zoneinfo" module. Patch by Paul Ganssle.

* bpo-40645: The "hmac.HMAC" exposes internal implementation details.
  The attributes "digest_cons", "inner", and "outer" are deprecated
  and will be removed in the future.

* bpo-40645: The internal module "_hashlib" wraps and exposes
  OpenSSL’s HMAC API. The new code will be used in Python 3.10 after
  the internal implementation details of the pure Python HMAC module
  are no longer part of the public API.

* bpo-40637: Builtin hash modules can now be disabled or selectively
  enabled with "configure --with-builtin-hashlib-hashes=sha3,blake1"
  or "--without-builtin-hashlib-hashes".

* bpo-37630: The "hashlib" module can now use SHA3 hashes and SHAKE
  XOF from OpenSSL when available.

* bpo-40479: The "hashlib" now compiles with OpenSSL 3.0.0-alpha2.

* bpo-40257: Revert changes to "inspect.getdoc()".

* bpo-40607: When cancelling a task due to timeout,
  "asyncio.wait_for()" will now propagate the exception if an error
  happens during cancellation. Patch by Roman Skurikhin.

* bpo-40612: Fix edge cases in SyntaxError formatting. If the offset
  is <= 0, no caret is printed. If the offset is > line length, the
  caret is printed pointing just after the last character.

* bpo-40597: If text content lines are longer than
  policy.max_line_length, always use a content-encoding to make sure
  they are wrapped.

* bpo-40571: Added functools.cache() as a simpler, more discoverable
  way to access the unbounded cache variant of
  lru_cache(maxsize=None).

* bpo-40503: **PEP 615**, the "zoneinfo" module. Adds support for the
  IANA time zone database.

* bpo-40397: Removed attributes "__args__" and "__parameters__" from
  special generic aliases like "typing.List" (not subscripted).

* bpo-40549: Convert posixmodule.c (“posix” or “nt” module) to the
  multiphase initialization (PEP 489).

* bpo-31033: Add a "msg" argument to "Future.cancel()" and
  "Task.cancel()".

* bpo-40541: Added an optional *counts* parameter to random.sample().

* bpo-40515: The "ssl" and "hashlib" modules now actively check that
  OpenSSL is build with thread support. Python 3.7.0 made thread
  support mandatory and no longer works safely with a no-thread
  builds.

* bpo-31033: When a "asyncio.Task" is cancelled, the exception
  traceback now chains all the way back to where the task was first
  interrupted.

* bpo-40504: "functools.lru_cache()" objects can now be the targets of
  weakrefs.

* bpo-40559: Fix possible memory leak in the C implementation of
  "asyncio.Task".

* bpo-40480: "fnmatch.fnmatch()" could take exponential time in the
  presence of multiple "*" pattern characters.  This was repaired by
  generating more elaborate regular expressions to avoid futile
  backtracking.

* bpo-40495: "compileall" is now able to use hardlinks to prevent
  duplicates in a case when ".pyc" files for different optimization
  levels have the same content.

* bpo-40457: The ssl module now support OpenSSL builds without TLS 1.0
  and 1.1 methods.

* bpo-40355: Improve error reporting in "ast.literal_eval()" in the
  presence of malformed "ast.Dict" nodes instead of silently ignoring
  any non-conforming elements. Patch by Curtis Bucher.

* bpo-40465: Deprecated the optional *random* argument to
  *random.shuffle()*.

* bpo-40459: "platform.win32_ver()" now produces correct *ptype*
  strings instead of empty strings.

* bpo-39435: The first argument of "pickle.loads()" is now positional-
  only.

* bpo-39305: Update "nntplib" to merge "nntplib.NNTP" and
  "nntplib._NNTPBase". Patch by Dong-hee Na.

* bpo-32494: Update "dbm.gnu" to use gdbm_count if possible when
  calling "len()". Patch by Dong-hee Na.

* bpo-40453: Add "isolated=True" keyword-only parameter to
  "_xxsubinterpreters.create()". An isolated subinterpreter cannot
  spawn threads, spawn a child process or call "os.fork()".

* bpo-40286: Remove "_random.Random.randbytes()": the C implementation
  of "randbytes()". Implement the method in Python to ease
  subclassing: "randbytes()" now directly reuses "getrandbits()".

* bpo-40394: Added default arguments to
  "difflib.SequenceMatcher.find_longest_match()".

* bpo-39995: Fix a race condition in concurrent.futures._ThreadWakeup:
  access to _ThreadWakeup is now protected with the shutdown lock.

* bpo-30966: "Process.shutdown(wait=True)" of "concurrent.futures" now
  closes explicitly the result queue.

* bpo-30966: Add a new "close()" method to the "SimpleQueue" class to
  explicitly close the queue.

* bpo-39966: Revert bpo-25597. "unittest.mock.MagicMock" with wraps’
  set uses default return values for magic methods.

* bpo-39791: Added "files()" function to importlib.resources with
  support for subdirectories in package data, matching backport in
  importlib_resources 1.5.

* bpo-40375: "imaplib.IMAP4.unselect()" is added. Patch by Dong-hee
  Na.

* bpo-40389: "repr()" now returns "typing.Optional[T]" when called for
  "typing.Union" of two types, one of which is "NoneType".

* bpo-40291: Add support for CAN_J1939 sockets (available on Linux
  5.4+)

* bpo-40273: "types.MappingProxyType" is now reversible.

* bpo-39075: The repr for "types.SimpleNamespace" is now insertion
  ordered rather than alphabetical.

* bpo-40192: On AIX, "thread_time()" is now implemented with
  "thread_cputime()" which has nanosecond resolution, rather than
  "clock_gettime(CLOCK_THREAD_CPUTIME_ID)" which has a resolution of
  10 ms. Patch by Batuhan Taskaya.

* bpo-40025: Raise TypeError when _generate_next_value_ is defined
  after members. Patch by Ethan Onstott.

* bpo-39058: In the argparse module, the repr for Namespace() and
  other argument holders now displayed in the order attributes were
  added. Formerly, it displayed in alphabetical order even though
  argument order is preserved the user visible parts of the module.

* bpo-24416: The "isocalendar()" methods of "datetime.date" and
  "datetime.datetime" now return a *named tuple* instead of a "tuple".


Documentation
-------------

* bpo-34790: Add version of removal for explicit passing of coros to
  "asyncio.wait()"’s documentation

* bpo-40561: Provide docstrings for webbrowser open functions.

* bpo-40499: Mention that "asyncio.wait()" requires a non-empty set of
  awaitables.

* bpo-39705: Tutorial example for sorted() in the Loop Techniques
  section is given a better explanation. Also a new example is
  included to explain sorted()’s basic behavior.

* bpo-39435: Fix an incorrect signature for "pickle.loads()" in the
  docs


Tests
-----

* bpo-40055: distutils.tests now saves/restores warnings filters to
  leave them unchanged. Importing tests imports docutils which imports
  pkg_resources which adds a warnings filter.

* bpo-40436: test_gdb and test.pythoninfo now check gdb command exit
  code.


Build
-----

* bpo-40653: Move _dirnameW out of HAVE_SYMLINK to fix a potential
  compiling issue.

* bpo-40514: Add "--with-experimental-isolated-subinterpreters" build
  option to "configure": better isolate subinterpreters, experimental
  build mode.


Windows
-------

* bpo-40650: Include winsock2.h in pytime.c for timeval.

* bpo-40458: Increase reserved stack space to prevent overflow crash
  on Windows.

* bpo-39148: Add IPv6 support to "asyncio" datagram endpoints in
  ProactorEventLoop. Change the raised exception for unknown address
  families to ValueError as it’s not coming from Windows API.


macOS
-----

* bpo-34956: When building Python on macOS from source, "_tkinter" now
  links with non-system Tcl and Tk frameworks if they are installed in
  "/Library/Frameworks", as had been the case on older releases of
  macOS. If a macOS SDK is explicitly configured, by using "--enable-
  universalsdk=" or "-isysroot", only the SDK itself is searched. The
  default behavior can still be overridden with "--with-tcltk-
  includes" and "--with-tcltk-libs".

* bpo-35569: Expose RFC 3542 IPv6 socket options.


Tools/Demos
-----------

* bpo-40479: Update multissltest helper to test with latest OpenSSL
  1.0.2, 1.1.0, 1.1.1, and 3.0.0-alpha.

* bpo-40431: Fix a syntax typo in "turtledemo" that now raises a
  "SyntaxError".

* bpo-40163: Fix multissltest tool. OpenSSL has changed download URL
  for old releases. The multissltest tool now tries to download from
  current and old download URLs.


C API
-----

* bpo-39465: Remove the "_PyUnicode_ClearStaticStrings()" function
  from the C API.

* bpo-38787: Add PyCFunction_CheckExact() macro for exact type checks
  now that we allow subtypes of PyCFunction, as well as
  PyCMethod_CheckExact() and PyCMethod_Check() for the new PyCMethod
  subtype.

* bpo-40545: Declare "_PyErr_GetTopmostException()" with
  "PyAPI_FUNC()" to properly export the function in the C API. The
  function remains private ("_Py") prefix.

* bpo-40412: Nullify inittab_copy during finalization, preventing
  future interpreter initializations in an embedded situation from
  crashing. Patch by Gregory Szorc.

* bpo-40429: The "PyThreadState_GetFrame()" function now returns a
  strong reference to the frame.

* bpo-40428: Remove the following functions from the C API. Call
  "PyGC_Collect()" explicitly to free all free lists.

  * "PyAsyncGen_ClearFreeLists()"

  * "PyContext_ClearFreeList()"

  * "PyDict_ClearFreeList()"

  * "PyFloat_ClearFreeList()"

  * "PyFrame_ClearFreeList()"

  * "PyList_ClearFreeList()"

  * "PySet_ClearFreeList()"

  * "PyTuple_ClearFreeList()"

* bpo-40421: New "PyFrame_GetBack()" function: get the frame next
  outer frame.

* bpo-40421: New "PyFrame_GetCode()" function: return a borrowed
  reference to the frame code.

* bpo-40217: Ensure that instances of types created with
  "PyType_FromSpecWithBases()" will visit its class object when
  traversing references in the garbage collector (implemented as an
  extension of the provided "tp_traverse"). Patch by Pablo Galindo.

* bpo-38787: Module C state is now accessible from C-defined heap type
  methods (**PEP 573**). Patch by Marcel Plch and Petr Viktorin.


Python 3.9.0 alpha 6
====================

*Release date: 2020-04-27*


Security
--------

* bpo-40121: Fixes audit events raised on creating a new socket.

* bpo-39073: Disallow CR or LF in email.headerregistry.Address
  arguments to guard against header injection attacks.

* bpo-39503: CVE-2020-8492: The "AbstractBasicAuthHandler" class of
  the "urllib.request" module uses an inefficient regular expression
  which can be exploited by an attacker to cause a denial of service.
  Fix the regex to prevent the catastrophic backtracking.
  Vulnerability reported by Ben Caller and Matt Schwager.


Core and Builtins
-----------------

* bpo-40313: Improve the performance of bytes.hex().

* bpo-40334: Switch to a new parser, based on PEG.  For more details
  see PEP 617. To temporarily switch back to the old parser, use "-X
  oldparser" or "PYTHONOLDPARSER=1".  In Python 3.10 we will remove
  the old parser completely, including the "parser" module (already
  deprecated) and anything that depends on it.

* bpo-40267: Fix the tokenizer to display the correct error message,
  when there is a SyntaxError on the last input character and no
  newline follows. It used to be "unexpected EOF while parsing", while
  it should be "invalid syntax".

* bpo-39522: Correctly unparse explicit "u" prefix for strings when
  postponed evaluation for annotations activated. Patch by Batuhan
  Taskaya.

* bpo-40246: Report a specialized error message, "invalid string
  prefix", when the tokenizer encounters a string with an invalid
  prefix.

* bpo-40082: Fix the signal handler: it now always uses the main
  interpreter, rather than trying to get the current Python thread
  state.

* bpo-37388: str.encode() and str.decode() no longer check the
  encoding and errors in development mode or in debug mode during
  Python finalization. The codecs machinery can no longer work on very
  late calls to str.encode() and str.decode().

* bpo-40077: Fix possible refleaks in "_json", memo of PyScannerObject
  should be traversed.

* bpo-37207: Speed up calls to "dict()" by using the **PEP 590**
  "vectorcall" calling convention.

* bpo-40141: Add column and line information to "ast.keyword" nodes.
  Patch by Pablo Galindo.

* bpo-1635741: Port "resource" to multiphase initialization (**PEP
  489**).

* bpo-1635741: Port "math" to multiphase initialization (**PEP 489**).

* bpo-1635741: Port _uuid module to multiphase initialization (**PEP
  489**).

* bpo-40077: Convert json module to use "PyType_FromSpec()".

* bpo-40067: Improve the error message for multiple star expressions
  in an assignment. Patch by Furkan Onder

* bpo-1635741: Port _functools module to multiphase initialization
  (PEP 489). Patch by Paulo Henrique Silva.

* bpo-1635741: Port operator module to multiphase initialization (PEP
  489). Patch by Paulo Henrique Silva.

* bpo-20526: Fix "PyThreadState_Clear()". "PyThreadState.frame" is a
  borrowed reference, not a strong reference: "PyThreadState_Clear()"
  must not call "Py_CLEAR(tstate->frame)".

* bpo-1635741: Port time module to multiphase initialization (**PEP
  489**). Patch by Paulo Henrique Silva.

* bpo-1635741: Port _weakref extension module to multiphase
  initialization (**PEP 489**).

* bpo-40020: Fix a leak and subsequent crash in parsetok.c caused by
  realloc misuse on a rare codepath.

* bpo-39939: Added str.removeprefix and str.removesuffix methods and
  corresponding bytes, bytearray, and collections.UserString methods
  to remove affixes from a string if present. See **PEP 616** for a
  full description. Patch by Dennis Sweeney.

* bpo-39481: Implement PEP 585. This supports list[int], tuple[str, …]
  etc.

* bpo-32894: Support unparsing of infinity numbers in postponed
  annotations. Patch by Batuhan Taşkaya.

* bpo-37207: Speed up calls to "list()" by using the **PEP 590**
  "vectorcall" calling convention. Patch by Mark Shannon.


Library
-------

* bpo-40398: "typing.get_args()" now always returns an empty tuple for
  special generic aliases.

* bpo-40396: Functions "typing.get_origin()", "typing.get_args()" and
  "typing.get_type_hints()" support now generic aliases like
  "list[int]".

* bpo-38061: Optimize the "subprocess" module on FreeBSD using
  "closefrom()". A single "close(fd)" syscall is cheap, but when
  "sysconf(_SC_OPEN_MAX)" is high, the loop calling "close(fd)" on
  each file descriptor can take several milliseconds.

  The workaround on FreeBSD to improve performance was to load and
  mount the fdescfs kernel module, but this is not enabled by default.

  Initial patch by Ed Maste (emaste), Conrad Meyer (cem), Kyle Evans
  (kevans) and Kubilay Kocak (koobs):
  https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=242274

* bpo-38061: On FreeBSD, "os.closerange(fd_low, fd_high)" now calls
  "closefrom(fd_low)" if *fd_high* is greater than or equal to
  "sysconf(_SC_OPEN_MAX)".

  Initial patch by Ed Maste (emaste), Conrad Meyer (cem), Kyle Evans
  (kevans) and Kubilay Kocak (koobs):
  https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=242274

* bpo-40360: The "lib2to3" module is pending deprecation due to **PEP
  617**.

* bpo-40138: Fix the Windows implementation of "os.waitpid()" for exit
  code larger than "INT_MAX >> 8". The exit status is now interpreted
  as an unsigned number.

* bpo-39942: Set “__main__” as the default module name when “__name__”
  is missing in "typing.TypeVar". Patch by Weipeng Hong.

* bpo-40275: The "logging" package is now imported lazily in
  "unittest" only when the "assertLogs()" assertion is used.

* bpo-40275: The "asyncio" package is now imported lazily in
  "unittest" only when the "IsolatedAsyncioTestCase" class is used.

* bpo-40330: In "ShareableList.__setitem__()", check the size of a new
  string item after encoding it to utf-8, not before.

* bpo-40148: Added "pathlib.Path.with_stem()" to create a new Path
  with the stem replaced.

* bpo-40325: Deprecated support for set objects in random.sample().

* bpo-40257: Improved help for the "typing" module. Docstrings are now
  shown for all special forms and special generic aliases (like
  "Union" and "List"). Using "help()" with generic alias like
  "List[int]" will show the help for the correspondent concrete type
  ("list" in this case).

* bpo-40257: func:"inspect.getdoc" no longer returns docstring
  inherited from the type of the object or from parent class if it is
  a class if it is not defined in the object itself. In "pydoc" the
  documentation string is now shown not only for class, function,
  method etc, but for any object that has its own "__doc__" attribute.

* bpo-40287: Fixed "SpooledTemporaryFile.seek()" to return the
  position.

* bpo-40290: Added zscore() to statistics.NormalDist().

* bpo-40282: Allow "random.getrandbits(0)" to succeed and to return 0.

* bpo-40286: Add "random.randbytes()" function and
  "random.Random.randbytes()" method to generate random bytes.

* bpo-40277: "collections.namedtuple()" now provides a human-readable
  repr for its field accessors.

* bpo-40270: The included copy of sqlite3 on Windows is now compiled
  with the json extension. This allows the use of functions such as
  "json_object".

* bpo-29255: Wait in "KqueueSelector.select" when no fds are
  registered

* bpo-40260: Ensure "modulefinder" uses "io.open_code()" and respects
  coding comments.

* bpo-40234: Allow again to spawn daemon threads in subinterpreters
  (revert change which denied them).

* bpo-39207: Workers in "ProcessPoolExecutor" are now spawned on
  demand, only when there are no available idle workers to reuse. This
  optimizes startup overhead and reduces the amount of lost CPU time
  to idle workers. Patch by Kyle Stanley.

* bpo-40091: Fix a hang at fork in the logging module: the new private
  _at_fork_reinit() method is now used to reinitialize locks at fork
  in the child process.

* bpo-40149: Implement traverse and clear slots in _abc._abc_data
  type.

* bpo-40208: Remove deprecated "symtable.SymbolTable.has_exec()".

* bpo-40196: Fix a bug in the "symtable" module that was causing
  incorrectly report global variables as local. Patch by Pablo
  Galindo.

* bpo-40190: Add support for "_SC_AIX_REALMEM" to "posix.sysconf()".

* bpo-40182: Removed the "_field_types" attribute of the
  "typing.NamedTuple" class.

* bpo-36517: Multiple inheritance with "typing.NamedTuple" now raises
  an error instead of silently ignoring other types.

* bpo-40126: Fixed reverting multiple patches in unittest.mock.
  Patcher’s "__exit__()" is now never called if its "__enter__()" is
  failed. Returning true from "__exit__()" silences now the exception.

* bpo-40094: CGIHTTPRequestHandler of http.server now logs the CGI
  script exit code, rather than the CGI script exit status of
  os.waitpid(). For example, if the script is killed by signal 11, it
  now logs: “CGI script exit code -11.”

* bpo-40108: Improve the error message when triying to import a module
  using "runpy" and incorrently use the “.py” extension at the end of
  the module name. Patch by Pablo Galindo.

* bpo-40094: Add "os.waitstatus_to_exitcode()" function: convert a
  wait status to an exit code.

* bpo-40089: Fix threading._after_fork(): if fork was not called by a
  thread spawned by threading.Thread, threading._after_fork() now
  creates a _MainThread instance for _main_thread, instead of a
  _DummyThread instance.

* bpo-40089: Add a private "_at_fork_reinit()" method to
  "_thread.Lock", "_thread.RLock", "threading.RLock" and
  "threading.Condition" classes: reinitialize the lock at fork in the
  child process, reset the lock to the unlocked state. Rename also the
  private "_reset_internal_locks()" method of "threading.Event" to
  "_at_fork_reinit()".

* bpo-25780: Expose "CAN_RAW_JOIN_FILTERS" in the "socket" module.

* bpo-39503: "AbstractBasicAuthHandler" of "urllib.request" now parses
  all WWW-Authenticate HTTP headers and accepts multiple challenges
  per header: use the realm of the first Basic challenge.

* bpo-39812: Removed daemon threads from "concurrent.futures" by
  adding an internal "threading._register_atexit()", which calls
  registered functions prior to joining all non-daemon threads. This
  allows for compatibility with subinterpreters, which don’t support
  daemon threads.

* bpo-40050: Fix "importlib._bootstrap_external": avoid creating a new
  "winreg" builtin module if it’s already available in "sys.modules",
  and remove redundant imports.

* bpo-40014: Fix "os.getgrouplist()": if "getgrouplist()" function
  fails because the group list is too small, retry with a larger group
  list. On failure, the glibc implementation of "getgrouplist()" sets
  "ngroups" to the total number of groups. For other implementations,
  double the group list size.

* bpo-40017: Add "time.CLOCK_TAI" constant if the operating system
  support it.

* bpo-40016: In re docstring, clarify the relationship between inline
  and argument compile flags.

* bpo-39953: Update internal table of OpenSSL error codes in the "ssl"
  module.

* bpo-36144: Added **PEP 584** operators to
  "weakref.WeakValueDictionary".

* bpo-36144: Added **PEP 584** operators to
  "weakref.WeakKeyDictionary".

* bpo-38891: Fix linear runtime behaviour of the "__getitem__" and
  "__setitem__" methods in
  "multiprocessing.shared_memory.ShareableList". This avoids quadratic
  performance when iterating a "ShareableList". Patch by Thomas
  Krennwallner.

* bpo-39682: Remove undocumented support for *closing* a
  "pathlib.Path" object via its context manager. The context manager
  magic methods remain, but they are now a no-op, making "Path"
  objects immutable.

* bpo-36144: Added **PEP 584** operators ("|" and "|=") to
  "collections.ChainMap".

* bpo-39011: Normalization of line endings in ElementTree attributes
  was removed, as line endings which were replaced by entity numbers
  should be preserved in original form.

* bpo-38410: Properly handle "sys.audit()" failures in
  "sys.set_asyncgen_hooks()".

* bpo-36541: lib2to3 now recognizes named assignment expressions (the
  walrus operator, ":=")

* bpo-35967: In platform, delay the invocation of ‘uname -p’ until the
  processor attribute is requested.

* bpo-35113: "inspect.getsource()" now returns correct source code for
  inner class with same name as module level class. Decorators are
  also returned as part of source of the class. Patch by Karthikeyan
  Singaravelan.

* bpo-33262: Deprecate passing None as an argument for
  "shlex.split()"’s "s" parameter.  Patch by Zackery Spytz.

* bpo-31758: Prevent crashes when using an uninitialized
  "_elementtree.XMLParser" object. Patch by Oren Milman.


Documentation
-------------

* bpo-27635: The pickle documentation incorrectly claimed that
  "__new__" isn’t called by default when unpickling.

* bpo-39879: Updated Data model docs to include "dict()" insertion
  order preservation. Patch by Furkan Onder and Samy Lahfa.

* bpo-38387: Document "PyDoc_STRVAR" macro in the C-API reference.

* bpo-13743: Some methods within xml.dom.minidom.Element class are now
  better documented.


Tests
-----

* bpo-31904: Set expected default encoding in
  test_c_locale_coercion.py for VxWorks RTOS.

* bpo-40162: Update Travis CI configuration to OpenSSL 1.1.1f.

* bpo-40146: Update OpenSSL to 1.1.1f in Azure Pipelines.

* bpo-40094: Add "test.support.wait_process()" function.

* bpo-40003: "test.bisect_cmd" now copies Python command line options
  like "-O" or "-W". Moreover, emit a warning if "test.bisect_cmd" is
  used with "-w"/"--verbose2" option.

* bpo-39380: Add the encoding in "ftplib.FTP" and "ftplib.FTP_TLS" to
  the constructor as keyword-only and change the default from
  "latin-1" to "utf-8" to follow **RFC 2640**.

* bpo-39793: Use the same domain when testing "make_msgid". Patch by
  Batuhan Taskaya.

* bpo-1812: Fix newline handling in doctest.testfile when loading from
  a package whose loader has a get_data method. Patch by Peter Donis.


Build
-----

* bpo-38360: Support single-argument form of macOS -isysroot flag.

* bpo-40158: Fix CPython MSBuild Properties in NuGet Package
  (build/native/python.props)

* bpo-38527: Fix configure check on Solaris for “float word ordering”:
  sometimes, the correct “grep” command was not being used. Patch by
  Arnon Yaari.


Windows
-------

* bpo-40164: Updates Windows to OpenSSL 1.1.1f

* bpo-8901: Ignore the Windows registry when the "-E" option is used.


macOS
-----

* bpo-38329: python.org macOS installers now update the Current
  version symlink of /Library/Frameworks/Python.framework/Versions for
  3.9 installs. Previously, Current was only updated for Python 2.x
  installs. This should make it easier to embed Python 3 into other
  macOS applications.

* bpo-40164: Update macOS installer builds to use OpenSSL 1.1.1g.


IDLE
----

* bpo-38439: Add a 256×256 pixel IDLE icon to support more modern
  environments. Created by Andrew Clover. Delete the unused macOS
  idle.icns icon file.

* bpo-38689: IDLE will no longer freeze when inspect.signature fails
  when fetching a calltip.


Tools/Demos
-----------

* bpo-40385: Removed the checkpyc.py tool. Please see compileall
  without force mode as a potential alternative.

* bpo-40179: Fixed translation of "#elif" in Argument Clinic.

* bpo-40094: Fix "which.py" script exit code: it now uses
  "os.waitstatus_to_exitcode()" to convert "os.system()" exit status
  into an exit code.


C API
-----

* bpo-40241: Move the "PyGC_Head" structure to the internal C API.

* bpo-40170: Convert "PyObject_IS_GC()" macro to a function to hide
  implementation details.

* bpo-40241: Add the functions "PyObject_GC_IsTracked()" and
  "PyObject_GC_IsFinalized()" to the public API to allow to query if
  Python objects are being currently tracked or have been already
  finalized by the garbage collector respectively. Patch by Pablo
  Galindo.

* bpo-40170: The "PyObject_NEW()" macro becomes an alias to the
  "PyObject_New()" macro, and the "PyObject_NEW_VAR()" macro becomes
  an alias to the "PyObject_NewVar()" macro, to hide implementation
  details. They no longer access directly the
  "PyTypeObject.tp_basicsize" member.

* bpo-40170: "PyType_HasFeature()" now always calls
  "PyType_GetFlags()" to hide implementation details. Previously, it
  accessed directly the "PyTypeObject.tp_flags" member when the
  limited C API was not used.

* bpo-40170: Convert the "PyObject_GET_WEAKREFS_LISTPTR()" macro to a
  function to hide implementation details: the macro accessed directly
  to the "PyTypeObject.tp_weaklistoffset" member.

* bpo-40170: Convert "PyObject_CheckBuffer()" macro to a function to
  hide implementation details: the macro accessed directly the
  "PyTypeObject.tp_as_buffer" member.

* bpo-40170: Always declare "PyIndex_Check()" as an opaque function to
  hide implementation details: remove "PyIndex_Check()" macro. The
  macro accessed directly the "PyTypeObject.tp_as_number" member.

* bpo-39947: Add "PyThreadState_GetID()" function: get the unique
  identifier of a Python thread state.


Python 3.9.0 alpha 5
====================

*Release date: 2020-03-23*


Security
--------

* bpo-38576: Disallow control characters in hostnames in http.client,
  addressing CVE-2019-18348. Such potentially malicious header
  injection URLs now cause a InvalidURL to be raised.


Core and Builtins
-----------------

* bpo-40010: Optimize pending calls in multithreaded applications. If
  a thread different than the main thread schedules a pending call
  ("Py_AddPendingCall()"), the bytecode evaluation loop is no longer
  interrupted at each bytecode instruction to check for pending calls
  which cannot be executed. Only the main thread can execute pending
  calls.

  Previously, the bytecode evaluation loop was interrupted at each
  instruction until the main thread executes pending calls.

* bpo-1635741: Port _weakref extension module to multiphase
  initialization (**PEP 489**).

* bpo-1635741: Port _collections module to multiphase initialization
  (**PEP 489**).

* bpo-40010: Optimize signal handling in multithreaded applications.
  If a thread different than the main thread gets a signal, the
  bytecode evaluation loop is no longer interrupted at each bytecode
  instruction to check for pending signals which cannot be handled.
  Only the main thread of the main interpreter can handle signals.

  Previously, the bytecode evaluation loop was interrupted at each
  instruction until the main thread handles signals.

* bpo-39984: If "Py_AddPendingCall()" is called in a subinterpreter,
  the function is now scheduled to be called from the subinterpreter,
  rather than being called from the main interpreter. Each
  subinterpreter now has its own list of scheduled calls.

* bpo-1635741: Port _heapq module to multiphase initialization.

* bpo-1635741: Port itertools module to multiphase initialization
  (**PEP 489**).

* bpo-37207: Speed up calls to "frozenset()" by using the **PEP 590**
  "vectorcall" calling convention. Patch by Dong-hee Na.

* bpo-39984: subinterpreters: Move
  "_PyRuntimeState.ceval.tracing_possible" to
  "PyInterpreterState.ceval.tracing_possible": each interpreter now
  has its own variable.

* bpo-37207: Speed up calls to "set()" by using the **PEP 590**
  "vectorcall" calling convention. Patch by Dong-hee Na.

* bpo-1635741: Port _statistics module to multiphase initialization
  (**PEP 489**).

* bpo-39968: Use inline function to replace extension modules’
  get_module_state macros.

* bpo-39965: Correctly raise "SyntaxError" if *await* is used inside
  non-async functions and "PyCF_ALLOW_TOP_LEVEL_AWAIT" is set (like in
  the asyncio REPL). Patch by Pablo Galindo.

* bpo-39562: Allow executing asynchronous comprehensions on the top
  level when the "PyCF_ALLOW_TOP_LEVEL_AWAIT" flag is given. Patch by
  Batuhan Taskaya.

* bpo-37207: Speed up calls to "tuple()" by using the **PEP 590**
  "vectorcall" calling convention. Patch by Dong-hee Na.

* bpo-38373: Changed list overallocation strategy. It no longer
  overallocates if the new size is closer to overallocated size than
  to the old size and adds padding.

* bpo-39926: Update Unicode database to Unicode version 13.0.0.

* bpo-19466: Clear the frames of daemon threads earlier during the
  Python shutdown to call objects destructors. So “unclosed file”
  resource warnings are now emitted for daemon threads in a more
  reliable way.

* bpo-38894: Fix a bug that was causing incomplete results when
  calling "pathlib.Path.glob" in the presence of symlinks that point
  to files where the user does not have read access. Patch by Pablo
  Galindo and Matt Wozniski.

* bpo-39877: Fix "PyEval_RestoreThread()" random crash at exit with
  daemon threads. It now accesses the "_PyRuntime" variable directly
  instead of using "tstate->interp->runtime", since "tstate" can be a
  dangling pointer after "Py_Finalize()" has been called. Moreover,
  the daemon thread now exits before trying to take the GIL.

* bpo-39871: Fix a possible "SystemError" in
  "math.{atan2,copysign,remainder}()" when the first argument cannot
  be converted to a "float". Patch by Zackery Spytz.

* bpo-39776: Fix race condition where threads created by
  PyGILState_Ensure() could get a duplicate id.

  This affects consumers of tstate->id like the contextvar caching
  machinery, which could return invalid cached objects under heavy
  thread load (observed in embedded scenarios).

* bpo-39778: Fixed a crash due to incorrect handling of weak
  references in "collections.OrderedDict" classes. Patch by Pablo
  Galindo.

* bpo-1635741: Port audioop extension module to multiphase
  initialization (**PEP 489**).

* bpo-39702: Relax *decorator* grammar restrictions to allow any valid
  expression (**PEP 614**).

* bpo-38091: Tweak import deadlock detection code to not deadlock
  itself.

* bpo-1635741: Port _locale extension module to multiphase
  initialization (**PEP 489**).

* bpo-39087: Optimize "PyUnicode_AsUTF8()" and
  "PyUnicode_AsUTF8AndSize()" slightly when they need to create
  internal UTF-8 cache.

* bpo-39520: Fix unparsing of ext slices with no items ("foo[:,]").
  Patch by Batuhan Taskaya.

* bpo-39220: Do not optimize annotations if ‘from __future__ import
  annotations’ is used. Patch by Pablo Galindo.

* bpo-35712: Using "NotImplemented" in a boolean context has been
  deprecated. Patch contributed by Josh Rosenberg.

* bpo-22490: Don’t leak environment variable "__PYVENV_LAUNCHER__"
  into the interpreter session on macOS.


Library
-------

* bpo-39830: Add "zipfile.Path" to "__all__" in the "zipfile" module.

* bpo-40000: Improved error messages for validation of "ast.Constant"
  nodes. Patch by Batuhan Taskaya.

* bpo-39999: "__module__" of the AST node classes is now set to “ast”
  instead of “_ast”. Added docstrings for dummy AST node classes and
  deprecated attributes.

* bpo-39991: "uuid.getnode()" now skips IPv6 addresses with the same
  string length than a MAC address (17 characters): only use MAC
  addresses.

* bpo-39988: Deprecated "ast.AugLoad" and "ast.AugStore" node classes
  because they are no longer used.

* bpo-39656: Ensure "bin/python3.#" is always present in virtual
  environments on POSIX platforms - by Anthony Sottile.

* bpo-39969: Deprecated "ast.Param" node class because it’s no longer
  used. Patch by Batuhan Taskaya.

* bpo-39360: Ensure all workers exit when finalizing a
  "multiprocessing.Pool" implicitly via the module finalization
  handlers of multiprocessing. This fixes a deadlock situation that
  can be experienced when the Pool is not properly finalized via the
  context manager or a call to "multiprocessing.Pool.terminate". Patch
  by Batuhan Taskaya and Pablo Galindo.

* bpo-35370: sys.settrace(), sys.setprofile() and
  _lsprof.Profiler.enable() now properly report "PySys_Audit()" error
  if “sys.setprofile” or “sys.settrace” audit event is denied.

* bpo-39936: AIX: Fix _aix_support module when the subprocess is not
  available, when building Python from scratch. It now uses new
  private _bootsubprocess module, rather than having two
  implementations depending if subprocess is available or not. So
  _aix_support.aix_platform() result is now the same if subprocess is
  available or not.

* bpo-36144: "collections.OrderedDict" now implements "|" and "|="
  (**PEP 584**).

* bpo-39652: The column name found in "sqlite3.Cursor.description" is
  now truncated on the first ‘[’ only if the PARSE_COLNAMES option is
  set.

* bpo-39915: Ensure "unittest.mock.AsyncMock.await_args_list" has call
  objects in the order of awaited arguments instead of using
  "unittest.mock.Mock.call_args" which has the last value of the call.
  Patch by Karthikeyan Singaravelan.

* bpo-36144: Updated "os.environ" and "os.environb" to support **PEP
  584**’s merge ("|") and update ("|=") operators.

* bpo-38662: The "ensurepip" module now invokes "pip" via the "runpy"
  module. Hence it is no longer tightly coupled with the internal API
  of the bundled "pip" version, allowing easier updates to a newer
  "pip" version both internally and for distributors.

* bpo-38075: Fix the "random.Random.seed()" method when a "bool" is
  passed as the seed.

* bpo-39916: More reliable use of "os.scandir()" in "Path.glob()". It
  no longer emits a ResourceWarning when interrupted.

* bpo-39850: "multiprocessing" now supports abstract socket addresses
  (if abstract sockets are supported in the running platform). When
  creating arbitrary addresses (like when default-constructing
  "multiprocessing.connection.Listener" objects) abstract sockets are
  preferred to avoid the case when the temporary-file-generated
  address is too large for an AF_UNIX socket address. Patch by Pablo
  Galindo.

* bpo-36287: "ast.dump()" no longer outputs optional fields and
  attributes with default values. The default values for optional
  fields and attributes of AST nodes are now set as class attributes
  (e.g. "Constant.kind" is set to "None").

* bpo-39889: Fixed "ast.unparse()" for extended slices containing a
  single element (e.g. "a[i:j,]"). Remove redundant tuples when index
  with a tuple (e.g. "a[i, j]").

* bpo-39828: Fix "json.tool" to catch "BrokenPipeError". Patch by
  Dong-hee Na.

* bpo-13487: Avoid a possible *“RuntimeError: dictionary changed size
  during iteration”* from "inspect.getmodule()" when it tried to loop
  through "sys.modules".

* bpo-39674: Revert “bpo-37330: open() no longer accept ‘U’ in file
  mode”. The “U” mode of open() is kept in Python 3.9 to ease
  transition from Python 2.7, but will be removed in Python 3.10.

* bpo-28577: The hosts method on 32-bit prefix length IPv4Networks and
  128-bit prefix IPv6Networks now returns a list containing the single
  Address instead of an empty list.

* bpo-39826: Add getConnection method to logging HTTPHandler to enable
  custom connections.

* bpo-39763: Reimplement "distutils.spawn.spawn()" function with the
  "subprocess" module.

* bpo-39794: Add –without-decimal-contextvar build option.  This
  enables a thread-local rather than a coroutine local context.

* bpo-36144: "collections.defaultdict" now implements "|" (**PEP
  584**).

* bpo-39517: Fix runpy.run_path() when using pathlike objects

* bpo-39775: Change "inspect.Signature.parameters" back to
  "collections.OrderedDict". This was changed to "dict" in Python
  3.9.0a4.

* bpo-39678: Refactor queue_manager in
  "concurrent.futures.ProcessPoolExecutor" to make it easier to
  maintain.

* bpo-39764: Fix AttributeError when calling get_stack on a
  PyAsyncGenObject Task

* bpo-39769: The "compileall.compile_dir()" function’s *ddir*
  parameter and the compileall command line flag "-d" no longer write
  the wrong pathname to the generated pyc file for submodules beneath
  the root of the directory tree being compiled.  This fixes a
  regression introduced with Python 3.5.

* bpo-36144: "types.MappingProxyType" objects now support the merge
  ("|") operator from **PEP 584**.

* bpo-38691: The "importlib" module now ignores the "PYTHONCASEOK"
  environment variable when the "-E" or "-I" command line options are
  being used.

* bpo-39719: Remove "tempfile.SpooledTemporaryFile.softspace()" as
  files no longer have the "softspace" attribute in Python 3. Patch by
  Shantanu.

* bpo-39667: Improve pathlib.Path compatibility on zipfile.Path and
  correct performance degradation as found in zipp 3.0.

* bpo-39638: Keep ASDL signatures in the docstrings for "AST" nodes.
  Patch by Batuhan Taskaya

* bpo-39639: Deprecated "ast.Suite" node class because it’s no longer
  used. Patch by Batuhan Taskaya.

* bpo-39609: Add thread_name_prefix to default asyncio executor

* bpo-39548: Fix handling of header in
  "urllib.request.AbstractDigestAuthHandler" when the optional "qop"
  parameter is not present.

* bpo-39509: HTTP status codes "103 EARLY_HINTS" and "425 TOO_EARLY"
  are added to "http.HTTPStatus". Patch by Dong-hee Na.

* bpo-39507: Adding HTTP status 418 “I’m a Teapot” to HTTPStatus in
  http library. Patch by Ross Rhodes.

* bpo-39495: Remove default value from *attrs* parameter of
  "xml.etree.ElementTree.TreeBuilder.start()" for consistency between
  Python and C implementations.

* bpo-38971: Open issue in the BPO indicated a desire to make the
  implementation of codecs.open() at parity with io.open(), which
  implements a try/except to assure file stream gets closed before an
  exception is raised.

* bpo-38641: Added starred expressions support to "return" and "yield"
  statements for "lib2to3". Patch by Vlad Emelianov.

* bpo-37534: When using minidom module to generate XML documents the
  ability to add Standalone Document Declaration is added. All the
  changes are made to generate a document in compliance with
  Extensible Markup Language (XML) 1.0 (Fifth Edition) W3C
  Recommendation (available here: https://www.w3.org/TR/xml/#sec-
  prolog-dtd).

* bpo-34788: Add support for scoped IPv6 addresses to "ipaddress".
  Patch by Oleksandr Pavliuk.

* bpo-34822: Simplified AST for subscription. Simple indices are now
  represented by their value, extended slices are represented as
  tuples. "ast" classes "Index" and "ExtSlice" are considered
  deprecated and will be removed in future Python versions. In the
  meantime, "Index(value)" now returns a "value" itself,
  "ExtSlice(slices)" returns "Tuple(slices, Load())".


Documentation
-------------

* bpo-39868: Updated the Language Reference for **PEP 572**.

* bpo-13790: Change ‘string’ to ‘specification’ in format doc.

* bpo-17422: The language reference no longer restricts default class
  namespaces to dicts only.

* bpo-39530: Fix misleading documentation about mixed-type numeric
  comparisons.

* bpo-39718: Update "token" documentation to reflect additions in
  Python 3.8

* bpo-39677: Changed operand name of **MAKE_FUNCTION** from *argc* to
  *flags* for module "dis"


Tests
-----

* bpo-40019: test_gdb now skips tests if it detects that gdb failed to
  read debug information because the Python binary is optimized.

* bpo-27807: "test_site.test_startup_imports()" is now skipped if a
  path of "sys.path" contains a ".pth" file.

* bpo-26067: Do not fail test_shutil test_chown test when uid or gid
  of user cannot be resolved to a name.

* bpo-39855: test_subprocess.test_user() now skips the test on an user
  name if the user name doesn’t exist. For example, skip the test if
  the user “nobody” doesn’t exist on Linux.


Build
-----

* bpo-39761: Fix build with DTrace but without additional DFLAGS.

* bpo-39763: setup.py now uses a basic implementation of the
  "subprocess" module if the "subprocess" module is not available:
  before required C extension modules are built.

* bpo-1294959: Add "--with-platlibdir" option to the configure script:
  name of the platform-specific library directory, stored in the new
  "sys.platlibdir" attribute. It is used to build the path of
  platform-specific extension modules and the path of the standard
  library. It is equal to ""lib"" on most platforms. On Fedora and
  SuSE, it is equal to ""lib64"" on 64-bit platforms. Patch by Jan
  Matějek, Matěj Cepl, Charalampos Stratakis and Victor Stinner.


Windows
-------

* bpo-39930: Ensures the required "vcruntime140.dll" is included in
  install packages.

* bpo-39847: Avoid hang when computer is hibernated whilst waiting for
  a mutex (for lock-related objects from "threading") around 49-day
  uptime.

* bpo-38597: "distutils" will no longer statically link
  "vcruntime140.dll" when a redistributable version is unavailable.
  All future releases of CPython will include a copy of this DLL to
  ensure distributed extensions can continue to load.

* bpo-38380: Update Windows builds to use SQLite 3.31.1

* bpo-39789: Update Windows release build machines to Visual Studio
  2019 (MSVC 14.2).

* bpo-34803: Package for nuget.org now includes repository reference
  and bundled icon image.


macOS
-----

* bpo-38380: Update macOS builds to use SQLite 3.31.1


IDLE
----

* bpo-27115: For ‘Go to Line’, use a Query box subclass with IDLE
  standard behavior and improved error checking.

* bpo-39885: Since clicking to get an IDLE context menu moves the
  cursor, any text selection should be and now is cleared.

* bpo-39852: Edit “Go to line” now clears any selection, preventing
  accidental deletion. It also updates Ln and Col on the status bar.

* bpo-39781: Selecting code context lines no longer causes a jump.


Tools/Demos
-----------

* bpo-36184: Port python-gdb.py to FreeBSD. python-gdb.py now checks
  for “take_gil” function name to check if a frame tries to acquire
  the GIL, instead of checking for “pthread_cond_timedwait” which is
  specific to Linux and can be a different condition than the GIL.

* bpo-38080: Added support to fix "getproxies" in the
  "lib2to3.fixes.fix_urllib" module. Patch by José Roberto Meza
  Cabrera.


C API
-----

* bpo-40024: Add "PyModule_AddType()" helper function: add a type to a
  module. Patch by Dong-hee Na.

* bpo-39946: Remove "_PyRuntime.getframe" hook and remove
  "_PyThreadState_GetFrame" macro which was an alias to
  "_PyRuntime.getframe". They were only exposed by the internal C API.
  Remove also "PyThreadFrameGetter" type.

* bpo-39947: Add "PyThreadState_GetFrame()" function: get the current
  frame of a Python thread state.

* bpo-37207: Add _PyArg_NoKwnames helper function. Patch by Dong-hee
  Na.

* bpo-39947: Add "PyThreadState_GetInterpreter()": get the interpreter
  of a Python thread state.

* bpo-39947: Add "PyInterpreterState_Get()" function to the limited C
  API.

* bpo-35370: If "PySys_Audit()" fails in "PyEval_SetProfile()" or
  "PyEval_SetTrace()", log the error as an unraisable exception.

* bpo-39947: Move the static inline function flavor of
  Py_EnterRecursiveCall() and Py_LeaveRecursiveCall() to the internal
  C API: they access PyThreadState attributes. The limited C API
  provides regular functions which hide implementation details.

* bpo-39947: Py_TRASHCAN_BEGIN_CONDITION and Py_TRASHCAN_END macro no
  longer access PyThreadState attributes, but call new private
  _PyTrash_begin() and _PyTrash_end() functions which hide
  implementation details.

* bpo-39884: "PyDescr_NewMethod()" and "PyCFunction_NewEx()" now
  include the method name in the SystemError “bad call flags” error
  message to ease debug.

* bpo-39877: Deprecated "PyEval_InitThreads()" and
  "PyEval_ThreadsInitialized()". Calling "PyEval_InitThreads()" now
  does nothing.

* bpo-38249: "Py_UNREACHABLE" is now implemented with
  "__builtin_unreachable()" and analogs in release mode.

* bpo-38643: "PyNumber_ToBase()" now raises a "SystemError" instead of
  crashing when called with invalid base.

* bpo-39882: The "Py_FatalError()" function is replaced with a macro
  which logs automatically the name of the current function, unless
  the "Py_LIMITED_API" macro is defined.

* bpo-39824: Extension modules: "m_traverse", "m_clear" and "m_free"
  functions of "PyModuleDef" are no longer called if the module state
  was requested but is not allocated yet. This is the case immediately
  after the module is created and before the module is executed
  ("Py_mod_exec" function). More precisely, these functions are not
  called if "m_size" is greater than 0 and the module state (as
  returned by "PyModule_GetState()") is "NULL".

  Extension modules without module state ("m_size <= 0") are not
  affected.

* bpo-38913: Fixed segfault in "Py_BuildValue()" called with a format
  containing “#” and undefined PY_SSIZE_T_CLEAN whwn an exception is
  set.

* bpo-38500: Add a private API to get and set the frame evaluation
  function: add "_PyInterpreterState_GetEvalFrameFunc()" and
  "_PyInterpreterState_SetEvalFrameFunc()" C functions. The
  "_PyFrameEvalFunction" function type now takes a *tstate* parameter.


Python 3.9.0 alpha 4
====================

*Release date: 2020-02-25*


Security
--------

* bpo-39184: Add audit events to functions in "fcntl", "msvcrt", "os",
  "resource", "shutil", "signal" and "syslog".

* bpo-39401: Avoid unsafe DLL load at startup on Windows 7 and
  earlier.

* bpo-39184: Add audit events to command execution functions in os and
  pty modules.


Core and Builtins
-----------------

* bpo-39382: Fix a use-after-free in the single inheritance path of
  "issubclass()", when the "__bases__" of an object has a single
  reference, and so does its first item. Patch by Yonatan Goldschmidt.

* bpo-39573: Update clinic tool to use "Py_IS_TYPE()". Patch by Dong-
  hee Na.

* bpo-39619: Enable use of "os.chroot()" on HP-UX systems.

* bpo-39573: Add "Py_IS_TYPE()" static inline function to check
  whether the object *o* type is *type*.

* bpo-39606: Fix regression caused by fix for bpo-39386, that
  prevented calling "aclose" on an async generator that had already
  been closed or exhausted.

* bpo-39579: Change the ending column offset of "Attribute" nodes
  constructed in "ast_for_dotted_name" to point at the end of the
  current node and not at the end of the last "NAME" node.

* bpo-1635741: Port _crypt extension module to multiphase
  initialization (**PEP 489**).

* bpo-1635741: Port _contextvars extension module to multiphase
  initialization (**PEP 489**).

* bpo-39510: Fix segfault in "readinto()" method on closed
  BufferedReader.

* bpo-39502: Fix "time.localtime()" on 64-bit AIX  to support years
  before 1902 and after 2038. Patch by M Felt.

* bpo-39492: Fix a reference cycle in the C Pickler that was
  preventing the garbage collection of deleted, pickled objects.

* bpo-39453: Fixed a possible crash in "list.__contains__()" when a
  list is changed during comparing items. Patch by Dong-hee Na.

* bpo-39434: *floor division* of float operation now has a better
  performance. Also the message of "ZeroDivisionError" for this
  operation is updated. Patch by Dong-hee Na.

* bpo-1635741: Port _codecs extension module to multiphase
  initialization (**PEP 489**).

* bpo-1635741: Port _bz2 extension module to multiphase initialization
  (**PEP 489**).

* bpo-1635741: Port _abc extension module to multiphase initialization
  (**PEP 489**).

* bpo-39320: Replace two complex bytecodes for building dicts with two
  simpler ones. The new bytecodes "DICT_MERGE" and "DICT_UPDATE" have
  been added The old bytecodes "BUILD_MAP_UNPACK" and
  "BUILD_MAP_UNPACK_WITH_CALL" have been removed.

* bpo-39219: Syntax errors raised in the tokenizer now always set
  correct “text” and “offset” attributes.

* bpo-36051: Drop the GIL during large "bytes.join" operations. Patch
  by Bruce Merry.

* bpo-38960: Fix DTrace build issues on FreeBSD. Patch by David
  Carlier.

* bpo-37207: Speed up calls to "range()" by about 30%, by using the
  PEP 590 "vectorcall" calling convention. Patch by Mark Shannon.

* bpo-36144: "dict" (and "collections.UserDict") objects now support
  PEP 584’s merge ("|") and update ("|=") operators. Patch by Brandt
  Bucher.

* bpo-32856: Optimized the idiom for assignment a temporary variable
  in comprehensions. Now "for y in [expr]" in comprehensions is as
  fast as a simple assignment "y = expr".


Library
-------

* bpo-30566: Fix "IndexError" when trying to decode an invalid string
  with punycode codec.

* bpo-39649: Remove obsolete check for "__args__" in
  bdb.Bdb.format_stack_entry.

* bpo-39648: Expanded "math.gcd()" and "math.lcm()" to handle multiple
  arguments.

* bpo-39681: Fix a regression where the C pickle module wouldn’t allow
  unpickling from a file-like object that doesn’t expose a readinto()
  method.

* bpo-35950: Raise "io.UnsupportedOperation" in
  "io.BufferedReader.truncate()" when it is called on a read-only
  "io.BufferedReader" instance.

* bpo-39479: Add "math.lcm()" function: least common multiple.

* bpo-39674: Revert “Do not expose abstract collection classes in the
  collections module” change (bpo-25988). Aliases to ABC like
  collections.Mapping are kept in Python 3.9 to ease transition from
  Python 2.7, but will be removed in Python 3.10.

* bpo-39104: Fix hanging ProcessPoolExcutor on "shutdown(wait=False)"
  when a task has failed pickling.

* bpo-39627: Fixed TypedDict totality check for inherited keys.

* bpo-39474: Fixed starting position of AST for expressions like
  "(a)(b)", "(a)[b]" and "(a).b".

* bpo-21016: The "pydoc" and "trace" modules now use the "sysconfig"
  module to get the path to the Python standard library, to support
  uncommon installation path like "/usr/lib64/python3.9/" on Fedora.
  Patch by Jan Matějek.

* bpo-39590: Collections.deque now holds strong references during
  deque.__contains__ and deque.count, fixing crashes.

* bpo-39586: The distutils "bdist_msi" command is deprecated in Python
  3.9, use "bdist_wheel" (wheel packages) instead.

* bpo-39595: Improved performance of zipfile.Path for files with a
  large number of entries. Also improved performance and fixed minor
  issue as published with importlib_metadata 1.5.

* bpo-39350: Fix regression in "fractions.Fraction" if the numerator
  and/or the denominator is an "int" subclass. The "math.gcd()"
  function is now used to normalize the *numerator* and *denominator*.
  "math.gcd()" always return a "int" type. Previously, the GCD type
  depended on *numerator* and *denominator*.

* bpo-39567: Added audit for "os.walk()", "os.fwalk()",
  "pathlib.Path.glob()" and "pathlib.Path.rglob()".

* bpo-39559: Remove unused, undocumented argument "getters" from
  "uuid.getnode()"

* bpo-38149: "sys.audit()" is now called only once per call of
  "glob.glob()" and "glob.iglob()".

* bpo-39546: Fix a regression in "ArgumentParser" where
  "allow_abbrev=False" was ignored for long options that used a prefix
  character other than “-“.

* bpo-39450: Striped whitespace from docstring before returning it
  from "unittest.case.shortDescription()".

* bpo-12915: A new function "resolve_name" has been added to the
  "pkgutil" module. This resolves a string of the form "'a.b.c.d'" or
  "'a.b:c.d'" to an object. In the example, "a.b" is a package/module
  and "c.d" is an object within that package/module reached via
  recursive attribute access.

* bpo-39353: The "binascii.crc_hqx()" function is no longer
  deprecated.

* bpo-39493: Mark "typing.IO.closed" as a property

* bpo-39491: Add "typing.Annotated" and "include_extras" parameter to
  "typing.get_type_hints()" as part of **PEP 593**. Patch by Till
  Varoquaux, documentation by Till Varoquaux and Konstantin Kashin.

* bpo-39485: Fix a bug in "unittest.mock.create_autospec()" that would
  complain about the wrong number of arguments for custom descriptors
  defined in an extension module returning functions.

* bpo-38932: Mock fully resets child objects on reset_mock(). Patch by
  Vegard Stikbakke

* bpo-39082: Allow AsyncMock to correctly patch static/class methods

* bpo-39432: Implement PEP-489 algorithm for non-ascii “PyInit_…”
  symbol names in distutils to make it export the correct init symbol
  also on Windows.

* bpo-18819: Omit "devmajor" and "devminor" fields for non-device
  files in "tarfile" archives, enabling bit-for-bit compatibility with
  GNU "tar(1)".

* bpo-39349: Added a new *cancel_futures* parameter to
  "concurrent.futures.Executor.shutdown()" that cancels all pending
  futures which have not started running, instead of waiting for them
  to complete before shutting down the executor.

* bpo-39274: "bool(fraction.Fraction)" now returns a boolean even if
  (numerator != 0) does not return a boolean (ex: numpy number).

* bpo-34793: Remove support for "with (await asyncio.lock):" and "with
  (yield from asyncio.lock):".  The same is correct for
  "asyncio.Condition" and "asyncio.Semaphore".

* bpo-25597: Ensure, if "wraps" is supplied to
  "unittest.mock.MagicMock", it is used to calculate return values for
  the magic methods instead of using the default return values. Patch
  by Karthikeyan Singaravelan.

* bpo-36350: "inspect.Signature.parameters" and
  "inspect.BoundArguments.arguments" are now dicts instead of
  OrderedDicts. Patch contributed by Rémi Lapeyre.

* bpo-35727: Fix sys.exit() and sys.exit(None) exit code propagation
  when used in multiprocessing.Process.

* bpo-32173: * Add "lazycache" function to "__all__". * Use
  "dict.clear" to clear the cache. * Refactoring "getline" function
  and "checkcache" function.


Documentation
-------------

* bpo-17422: The language reference now specifies restrictions on
  class namespaces. Adapted from a patch by Ethan Furman.

* bpo-39572: Updated documentation of "total" flag of "TypedDict".

* bpo-39654: In pyclbr doc, update ‘class’ to ‘module’ where
  appropriate and add readmodule comment. Patch by Hakan Çelik.

* bpo-39153: Clarify refcounting semantics for the following
  functions: - PyObject_SetItem - PyMapping_SetItemString -
  PyDict_SetItem - PyDict_SetItemString

* bpo-39392: Explain that when filling with turtle, overlap regions
  may be left unfilled.

* bpo-39369: Update mmap readline method description. The fact that
  the readline method does update the file position should not be
  ignored since this might give the impression for the programmer that
  it doesn’t update it.

* bpo-9056: Include subsection in TOC for PDF version of docs.


Tests
-----

* bpo-38325: Skip tests on non-BMP characters of test_winconsoleio.

* bpo-39502: Skip test_zipfile.test_add_file_after_2107() if
  "time.localtime()" fails with "OverflowError". It is the case on AIX
  6.1 for example.


Build
-----

* bpo-39489: Remove "COUNT_ALLOCS" special build.


Windows
-------

* bpo-39553: Delete unused code related to SxS manifests.

* bpo-39439: Honor the Python path when a virtualenv is active on
  Windows.

* bpo-39393: Improve the error message when attempting to load a DLL
  with unresolved dependencies.

* bpo-38883: "home()" and "expanduser()" on Windows now prefer
  "USERPROFILE" and no longer use "HOME", which is not normally set
  for regular user accounts. This makes them again behave like
  "os.path.expanduser()", which was changed to ignore "HOME" in 3.8,
  see bpo-36264.

* bpo-39185: The build.bat script has additional options for very-
  quiet output (-q) and very-verbose output (-vv)


IDLE
----

* bpo-39663: Add tests for pyparse find_good_parse_start().

* bpo-39600: In the font configuration window, remove duplicated font
  names.

* bpo-30780: Add remaining configdialog tests for buttons and
  highlights and keys tabs.

* bpo-39388: IDLE Settings Cancel button now cancels pending changes

* bpo-38792: Close an IDLE shell calltip if a "KeyboardInterrupt" or
  shell restart occurs.  Patch by Zackery Spytz.


C API
-----

* bpo-35081: Move the "bytes_methods.h" header file to the internal C
  API as "pycore_bytes_methods.h": it only contains private symbols
  (prefixed by "_Py"), except of the "PyDoc_STRVAR_shared()" macro.

* bpo-35081: Move the "dtoa.h" header file to the internal C API as
  "pycore_dtoa.h": it only contains private functions (prefixed by
  "_Py"). The "math" and "cmath" modules must now be compiled with the
  "Py_BUILD_CORE" macro defined.

* bpo-39573: Add "Py_SET_SIZE()" function to set the size of an
  object.

* bpo-39500: "PyUnicode_IsIdentifier()" does not call
  "Py_FatalError()" anymore if the string is not ready.

* bpo-39573: Add "Py_SET_TYPE()" function to set the type of an
  object.

* bpo-39573: Add a "Py_SET_REFCNT()" function to set the reference
  counter of an object.

* bpo-39542: Convert "PyType_HasFeature()", "PyType_Check()" and
  "PyType_CheckExact()" macros to static inline functions.

* bpo-39542: In the limited C API, "PyObject_INIT()" and
  "PyObject_INIT_VAR()" are now defined as aliases to
  "PyObject_Init()" and "PyObject_InitVar()" to make their
  implementation opaque. It avoids to leak implementation details in
  the limited C API. Exclude the following functions from the limited
  C API: "_Py_NewReference()", "_Py_ForgetReference()",
  "_PyTraceMalloc_NewReference()" and "_Py_GetRefTotal()".

* bpo-39542: Exclude trashcan mechanism from the limited C API: it
  requires access to PyTypeObject and PyThreadState structure fields,
  whereas these structures are opaque in the limited C API.

* bpo-39511: The "PyThreadState_Clear()" function now calls the
  "PyThreadState.on_delete" callback. Previously, that happened in
  "PyThreadState_Delete()".

* bpo-38076: Fix to clear the interpreter state only after clearing
  module globals to guarantee module state access from C Extensions
  during runtime destruction

* bpo-39245: The Vectorcall API (PEP 590) was made public, adding the
  functions "PyObject_Vectorcall", "PyObject_VectorcallMethod",
  "PyVectorcall_Function", "PyObject_CallOneArg",
  "PyObject_CallMethodNoArgs", "PyObject_CallMethodOneArg",
  "PyObject_FastCallDict", and the flag "Py_TPFLAGS_HAVE_VECTORCALL".


Python 3.9.0 alpha 3
====================

*Release date: 2020-01-24*


Core and Builtins
-----------------

* bpo-39427: Document all possibilities for the "-X" options in the
  command line help section. Patch by Pablo Galindo.

* bpo-39421: Fix possible crashes when operating with the functions in
  the "heapq" module and custom comparison operators.

* bpo-39386: Prevent double awaiting of async iterator.

* bpo-17005: Add "functools.TopologicalSorter" to the "functools"
  module to offers functionality to perform topological sorting of
  graphs. Patch by Pablo Galindo, Tim Peters and Larry Hastings.

* bpo-39320: Replace four complex bytecodes for building sequences
  with three simpler ones.

  The following four bytecodes have been removed:

  * BUILD_LIST_UNPACK

  * BUILD_TUPLE_UNPACK

  * BUILD_SET_UNPACK

  * BUILD_TUPLE_UNPACK_WITH_CALL

  The following three bytecodes have been added:

  * LIST_TO_TUPLE

  * LIST_EXTEND

  * SET_UPDATE

* bpo-39336: Import loaders which publish immutable module objects can
  now publish immutable packages in addition to individual modules.

* bpo-39322: Added a new function "gc.is_finalized()" to check if an
  object has been finalized by the garbage collector. Patch by Pablo
  Galindo.

* bpo-39048: Improve the displayed error message when incorrect types
  are passed to "async with" statements by looking up the
  "__aenter__()" special method before the "__aexit__()" special
  method when entering an asynchronous context manager. Patch by Géry
  Ogam.

* bpo-39235: Fix AST end location for lone generator expression in
  function call, e.g. f(i for i in a).

* bpo-39209: Correctly handle multi-line tokens in interactive mode.
  Patch by Pablo Galindo.

* bpo-1635741: Port _json extension module to multiphase
  initialization (**PEP 489**).

* bpo-39216: Fix constant folding optimization for positional only
  arguments - by Anthony Sottile.

* bpo-39215: Fix "SystemError" when nested function has annotation on
  positional-only argument - by Anthony Sottile.

* bpo-39200: Correct the error message when calling the "min()" or
  "max()" with no arguments. Patch by Dong-hee Na.

* bpo-39200: Correct the error message when trying to construct
  "range" objects with no arguments. Patch by Pablo Galindo.

* bpo-39166: Fix incorrect line execution reporting in trace functions
  when tracing the last iteration of asynchronous for loops. Patch by
  Pablo Galindo.

* bpo-39114: Fix incorrect line execution reporting in trace functions
  when tracing exception handlers with name binding. Patch by Pablo
  Galindo.

* bpo-39156: Split the COMPARE_OP bytecode instruction into four
  distinct instructions.

  * COMPARE_OP for rich comparisons

  * IS_OP for ‘is’ and ‘is not’ tests

  * CONTAINS_OP for ‘in’ and ‘is not’ tests

  * JUMP_IF_NOT_EXC_MATCH for checking exceptions in ‘try-except’
    statements.

  This improves the clarity of the interpreter and should provide a
  modest speedup.

* bpo-38588: Fix possible crashes in dict and list when calling
  "PyObject_RichCompareBool()".

* bpo-13601: By default, "sys.stderr" is line-buffered now, even if
  "stderr" is redirected to a file. You can still make "sys.stderr"
  unbuffered by passing the "-u" command-line option or setting the
  "PYTHONUNBUFFERED" environment variable.

  (Contributed by Jendrik Seipp in bpo-13601.)

* bpo-38610: Fix possible crashes in several list methods by holding
  strong references to list elements when calling
  "PyObject_RichCompareBool()".

* bpo-32021: Include brotli .br encoding in mimetypes encodings_map


Library
-------

* bpo-39430: Fixed race condition in lazy imports in "tarfile".

* bpo-39413: The "os.unsetenv()" function is now also available on
  Windows.

* bpo-39390: Fixed a regression with the "ignore" callback of
  "shutil.copytree()". The argument types are now str and List[str]
  again.

* bpo-39395: The "os.putenv()" and "os.unsetenv()" functions are now
  always available.

* bpo-39406: If "setenv()" C function is available, "os.putenv()" is
  now implemented with "setenv()" instead of "putenv()", so Python
  doesn’t have to handle the environment variable memory.

* bpo-39396: Fix "math.nextafter(-0.0, +0.0)" on AIX 7.1.

* bpo-29435: Allow "tarfile.is_tarfile()" to be used with file and
  file-like objects, like "zipfile.is_zipfile()". Patch by William
  Woodruff.

* bpo-39377: Removed "encoding" option from "json.loads()".  It has
  been deprecated since Python 3.1.

* bpo-39389: Write accurate compression level metadata in "gzip"
  archives, rather than always signaling maximum compression.

* bpo-39366: The previously deprecated "xpath()" and "xgtitle()"
  methods of "nntplib.NNTP" have been removed.

* bpo-39357: Remove the *buffering* parameter of "bz2.BZ2File". Since
  Python 3.0, it was ignored and using it was emitting
  "DeprecationWarning". Pass an open file object, to control how the
  file is opened. The *compresslevel* parameter becomes keyword-only.

* bpo-39353: Deprecate binhex4 and hexbin4 standards. Deprecate the
  "binhex" module and the following "binascii" functions: "b2a_hqx()",
  "a2b_hqx()", "rlecode_hqx()", "rledecode_hqx()", "crc_hqx()".

* bpo-39351: Remove "base64.encodestring()" and
  "base64.decodestring()", aliases deprecated since Python 3.1: use
  "base64.encodebytes()" and "base64.decodebytes()" instead.

* bpo-39350: Remove "fractions.gcd()" function, deprecated since
  Python 3.5 (bpo-22486): use "math.gcd()" instead.

* bpo-39329: "LMTP" constructor now has an optional *timeout*
  parameter. Patch by Dong-hee Na.

* bpo-39313: Add a new "exec_function" option (*–exec-function* in the
  CLI) to "RefactoringTool" for making "exec" a function. Patch by
  Batuhan Taskaya.

* bpo-39259: "FTP_TLS" and "FTP_TLS" now raise a "ValueError" if the
  given timeout for their constructor is zero to prevent the creation
  of a non-blocking socket. Patch by Dong-hee Na.

* bpo-39259: "SMTP" and "SMTP_SSL" now raise a "ValueError" if the
  given timeout for their constructor is zero to prevent the creation
  of a non-blocking socket. Patch by Dong-hee Na.

* bpo-39310: Add "math.ulp()": return the value of the least
  significant bit of a float.

* bpo-39297: Improved performance of importlib.metadata distribution
  discovery and resilients to inaccessible sys.path entries
  (importlib_metadata v1.4.0).

* bpo-39259: "NNTP" and "NNTP_SSL" now raise a "ValueError" if the
  given timeout for their constructor is zero to prevent the creation
  of a non-blocking socket. Patch by Dong-hee Na.

* bpo-38901: When you specify prompt=’.’ or equivalently python -m
  venv –prompt . … the basename of the current directory is used to
  set the created venv’s prompt when it’s activated.

* bpo-39288: Add "math.nextafter()": return the next floating-point
  value after *x* towards *y*.

* bpo-39259: "POP3" and "POP3_SSL" now raise a "ValueError" if the
  given timeout for their constructor is zero to prevent the creation
  of a non-blocking socket. Patch by Dong-hee Na.

* bpo-39242: Updated the Gmane domain from news.gmane.org to
  news.gmane.io which is used for examples of "NNTP" news reader
  server and nntplib tests.

* bpo-35292: Proxy the "SimpleHTTPRequestHandler.guess_type" to
  "mimetypes.guess_type" so the "mimetypes.init" is called lazily to
  avoid unnecessary costs when "http.server" module is imported.

* bpo-39239: The "select.epoll.unregister()" method no longer ignores
  the "EBADF" error.

* bpo-38907: In http.server script, restore binding to IPv4 on
  Windows.

* bpo-39152: Fix ttk.Scale.configure([name]) to return configuration
  tuple for name or all options.  Giovanni Lombardo contributed part
  of the patch.

* bpo-39198: If an exception were to be thrown in
  "Logger.isEnabledFor" (say, by asyncio timeouts or stopit) , the
  "logging" global lock may not be released appropriately, resulting
  in deadlock.  This change wraps that block of code with
  "try...finally" to ensure the lock is released.

* bpo-39191: Perform a check for running loop before starting a new
  task in "loop.run_until_complete()" to fail fast; it prevents the
  side effect of new task spawning before exception raising.

* bpo-38871: Correctly parenthesize filter-based statements that
  contain lambda expressions in mod:"lib2to3". Patch by Dong-hee Na.

* bpo-39142: A change was made to logging.config.dictConfig to avoid
  converting instances of named tuples to ConvertingTuple. It’s
  assumed that named tuples are too specialised to be treated like
  ordinary tuples; if a user of named tuples requires ConvertingTuple
  functionality, they will have to implement that themselves in their
  named tuple class.

* bpo-39158: ast.literal_eval() now supports empty sets.

* bpo-39129: Fix import path for "asyncio.TimeoutError"

* bpo-39057: "urllib.request.proxy_bypass_environment()" now ignores
  leading dots and no longer ignores a trailing newline.

* bpo-39056: Fixed handling invalid warning category in the -W option.
  No longer import the re module if it is not needed.

* bpo-39055: "base64.b64decode()" with "validate=True" raises now a
  binascii.Error if the input ends with a single "\n".

* bpo-21600: Fix "mock.patch.stopall()" to stop active patches that
  were created with "mock.patch.dict()".

* bpo-39019: Implement dummy "__class_getitem__" for
  "tempfile.SpooledTemporaryFile".

* bpo-39019: Implement dummy "__class_getitem__" for
  "subprocess.Popen", "subprocess.CompletedProcess"

* bpo-38914: Adjusted the wording of the warning issued by distutils’
  "check" command when the "author" and "maintainer" fields are
  supplied but no corresponding e-mail field ("author_email" or
  "maintainer_email") is found. The wording now reflects the fact that
  these fields are suggested, but not required. Patch by Juergen
  Gmach.

* bpo-38878: Fixed __subclasshook__ of "os.PathLike" to return a
  correct result upon inheritance. Patch by Bar Harel.

* bpo-38615: "IMAP4" and "IMAP4_SSL" now have an optional *timeout*
  parameter for their constructors. Also, the "open()" method now has
  an optional *timeout* parameter with this change. The overridden
  methods of "IMAP4_SSL" and "IMAP4_stream" were applied to this
  change. Patch by Dong-hee Na.

* bpo-35182: Fixed "Popen.communicate()" subsequent call crash when
  the child process has already closed any piped standard stream, but
  still continues to be running. Patch by Andriy Maletsky.

* bpo-38630: On Unix, "subprocess.Popen.send_signal()" now polls the
  process status. Polling reduces the risk of sending a signal to the
  wrong process if the process completed, the
  "subprocess.Popen.returncode" attribute is still "None", and the pid
  has been reassigned (recycled) to a new different process.

* bpo-38536: Removes trailing space in formatted currency with
  "international=True" and a locale with symbol following value. E.g.
  "locale.currency(12.34, international=True)" returned "'12,34 EUR '"
  instead of "'12,34 EUR'".

* bpo-38473: Use signature from inner mock for autospecced methods
  attached with "unittest.mock.attach_mock()". Patch by Karthikeyan
  Singaravelan.

* bpo-38361: Fixed an issue where "ident" could include a leading path
  separator when "syslog.openlog()" was called without arguments.

* bpo-38293: Add "copy.copy()" and "copy.deepcopy()" support to
  "property()" objects.

* bpo-37958: Added the pstats.Stats.get_profile_dict() method to
  return the profile data as a StatsProfile instance.

* bpo-28367: Termios magic constants for the following baud rates:   -
  B500000   - B576000   - B921600   - B1000000   - B1152000   -
  B1500000   - B2000000   - B2500000   - B3000000   - B3500000   -
  B4000000 Patch by Andrey Smirnov


Documentation
-------------

* bpo-39381: Mention in docs that "asyncio.get_event_loop()"
  implicitly creates new event loop only if called from the main
  thread.

* bpo-38918: Add an entry for "__module__" in the “function” &
  “method” sections of the "inspect" docs’ Types and members table.

* bpo-3530: In the "ast" module documentation, fix a misleading
  "NodeTransformer" example and add advice on when to use the
  "fix_missing_locations" function.


Build
-----

* bpo-39395: On non-Windows platforms, the "setenv()" and "unsetenv()"
  functions are now required to build Python.

* bpo-39160: Updated the documentation in "/configure --help" to show
  default values, reference documentation where required and add
  additional explanation where needed.

* bpo-39144: The ctags and etags build targets both include
  Modules/_ctypes and Python standard library source files.


IDLE
----

* bpo-39050: Make IDLE Settings dialog Help button work again.

* bpo-34118: Tag memoryview, range, and tuple as classes, the same as
  list, etcetera, in the library manual built-in functions list.

* bpo-32989: Add tests for editor newline_and_indent_event method.
  Remove dead code from pyparse find_good_parse_start method.


C API
-----

* bpo-39372: Clean header files of interfaces defined but with no
  implementation. The public API symbols being removed are:
  "_PyBytes_InsertThousandsGroupingLocale",
  "_PyBytes_InsertThousandsGrouping", "_Py_InitializeFromArgs",
  "_Py_InitializeFromWideArgs", "_PyFloat_Repr", "_PyFloat_Digits",
  "_PyFloat_DigitsInit", "PyFrame_ExtendStack",
  "_PyAIterWrapper_Type", "PyNullImporter_Type", "PyCmpWrapper_Type",
  "PySortWrapper_Type", "PyNoArgsFunction".

* bpo-39164: Add a private "_PyErr_GetExcInfo()" function to retrieve
  exception information of the specified Python thread state.


Python 3.9.0 alpha 2
====================

*Release date: 2019-12-18*


Security
--------

* bpo-38945: Newline characters have been escaped when performing uu
  encoding to prevent them from overflowing into to content section of
  the encoded file. This prevents malicious or accidental modification
  of data during the decoding process.

* bpo-37228: Due to significant security concerns, the *reuse_address*
  parameter of "asyncio.loop.create_datagram_endpoint()" is no longer
  supported. This is because of the behavior of "SO_REUSEADDR" in UDP.
  For more details, see the documentation for
  "loop.create_datagram_endpoint()". (Contributed by Kyle Stanley,
  Antoine Pitrou, and Yury Selivanov in bpo-37228.)

* bpo-38804: Fixes a ReDoS vulnerability in "http.cookiejar". Patch by
  Ben Caller.


Core and Builtins
-----------------

* bpo-39028: Slightly improve the speed of keyword argument parsing
  with many kwargs by strengthening the assumption that kwargs are
  interned strings.

* bpo-39080: Fix the value of *end_col_offset* for Starred Expression
  AST nodes when they are among the elements in the *args* attribute
  of Call AST nodes.

* bpo-39031: When parsing an “elif” node, lineno and col_offset of the
  node now point to the “elif” keyword and not to its condition,
  making it consistent with the “if” node. Patch by Lysandros
  Nikolaou.

* bpo-20443: In Python 3.9.0a1, sys.argv[0] was made an absolute path
  if a filename was specified on the command line. Revert this change,
  since most users expect sys.argv to be unmodified.

* bpo-39008: "PySys_Audit()" now requires "Py_ssize_t" to be used for
  size arguments in the format string, regardless of whether
  "PY_SSIZE_T_CLEAN" was defined at include time.

* bpo-38673: In REPL mode, don’t switch to PS2 if the line starts with
  comment or whitespace. Based on work by Batuhan Taşkaya.

* bpo-38922: Calling "replace" on a code object now raises the
  "code.__new__" audit event.

* bpo-38920: Add audit hooks for when "sys.excepthook()" and
  "sys.unraisablehook()" are invoked.

* bpo-38892: Improve documentation for audit events table and
  functions.

* bpo-38852: Set the thread stack size to 8 Mb for debug builds on
  android platforms.

* bpo-38858: Each Python subinterpreter now has its own “small integer
  singletons”: numbers in [-5; 257] range. It is no longer possible to
  change the number of small integers at build time by overriding
  "NSMALLNEGINTS" and "NSMALLPOSINTS" macros: macros should now be
  modified manually in "pycore_pystate.h" header file.

* bpo-36854: The garbage collector state becomes per interpreter
  ("PyInterpreterState.gc"), rather than being global
  ("_PyRuntimeState.gc").

* bpo-38835: The "PyFPE_START_PROTECT()" and "PyFPE_END_PROTECT()"
  macros are empty: they have been doing nothing for the last year, so
  stop using them.

* bpo-38328: Sped up the creation time of constant "list" and "set"
  displays. Patch by Brandt Bucher.

* bpo-38707: "MainThread.native_id" is now correctly reset in child
  processes spawned using "multiprocessing.Process", instead of
  retaining the parent’s value.

* bpo-38629: Added "__floor__" and "__ceil__" methods to float object.
  Patch by Batuhan Taşkaya.

* bpo-27145: int + int and int - int operators can now return small
  integer singletons. Patch by hongweipeng.

* bpo-38021: Provide a platform tag for AIX that is sufficient for
  PEP425 binary distribution identification. Patch by Michael Felt.

* bpo-35409: Ignore GeneratorExit exceptions when throwing an
  exception into the aclose coroutine of an asynchronous generator.

* bpo-33387: Removed WITH_CLEANUP_START, WITH_CLEANUP_FINISH,
  BEGIN_FINALLY, END_FINALLY, CALL_FINALLY and POP_FINALLY bytecodes.
  Replaced with RERAISE and WITH_EXCEPT_START bytecodes. The compiler
  now generates different code for exceptional and non-exceptional
  branches for ‘with’ and ‘try-except’ statements. For ‘try-finally’
  statements the ‘finally’ block is replicated for each exit from the
  ‘try’ body.


Library
-------

* bpo-39033: Fix "NameError" in "zipimport". Patch by Karthikeyan
  Singaravelan.

* bpo-39022: Update importlib.metadata to include improvements from
  importlib_metadata 1.3 including better serialization of EntryPoints
  and improved documentation for custom finders.

* bpo-39006: Fix asyncio when the ssl module is missing: only check
  for ssl.SSLSocket instance if the ssl module is available.

* bpo-38708: Fix a potential IndexError in email parser when parsing
  an empty msg-id.

* bpo-38698: Add a new "InvalidMessageID" token to email parser to
  represent invalid Message-ID headers.  Also, add defects when there
  is remaining value after parsing the header.

* bpo-38994: Implement "__class_getitem__" for "os.PathLike",
  "pathlib.Path".

* bpo-38979: Return class from "ContextVar.__class_getitem__" to
  simplify subclassing.

* bpo-38978: Implement "__class_getitem__" on asyncio objects (Future,
  Task, Queue). Patch by Batuhan Taskaya.

* bpo-38916: "array.array": Remove "tostring()" and "fromstring()"
  methods. They were aliases to "tobytes()" and "frombytes()",
  deprecated since Python 3.2.

* bpo-38986: Make repr of C accelerated TaskWakeupMethWrapper the same
  as of pure Python version.

* bpo-38982: Fix asyncio "PidfdChildWatcher": handle "waitpid()"
  error. If "waitpid()" is called elsewhere, "waitpid()" call fails
  with "ChildProcessError": use return code 255 in this case, and log
  a warning. It ensures that the pidfd file descriptor is closed if
  this error occurs.

* bpo-38529: Drop too noisy asyncio warning about deletion of a stream
  without explicit ".close()" call.

* bpo-27413: Added ability to pass through "ensure_ascii" options to
  json.dumps in the "json.tool" command-line interface.

* bpo-38634: The "readline" module now detects if Python is linked to
  libedit at runtime on all platforms.  Previously, the check was only
  done on macOS.

* bpo-33684: Fix "json.tool" failed to read a JSON file with non-ASCII
  characters when locale encoding is not UTF-8.

* bpo-38698: Prevent UnboundLocalError to pop up in parse_message_id.

  parse_message_id() was improperly using a token defined inside an
  exception handler, which was raising "UnboundLocalError" on parsing
  an invalid value. Patch by Claudiu Popa.

* bpo-38927: Use "python -m pip" instead of "pip" to upgrade
  dependencies in venv.

* bpo-26730: Fix "SpooledTemporaryFile.rollover()" might corrupt the
  file when it is in text mode. Patch by Serhiy Storchaka.

* bpo-38881: random.choices() now raises a ValueError when all the
  weights are zero.

* bpo-38876: Raise pickle.UnpicklingError when loading an item from
  memo for invalid input.

  The previous code was raising a "KeyError" for both the Python and C
  implementation. This was caused by the specified index of an invalid
  input which did not exist in the memo structure, where the pickle
  stores what objects it has seen. The malformed input would have
  caused either a "BINGET" or "LONG_BINGET" load from the memo,
  leading to a "KeyError" as the determined index was bogus. Patch by
  Claudiu Popa

* bpo-38688: Calling func:"shutil.copytree" to copy a directory tree
  from one directory to another subdirectory resulted in an endless
  loop and a RecursionError. A fix was added to consume an iterator
  and create the list of the entries to be copied, avoiding the
  recursion for newly created directories. Patch by Bruno P.
  Kinoshita.

* bpo-38863: Improve "is_cgi()" function in "http.server", which
  enables processing the case that cgi directory is a child of another
  directory other than root.

* bpo-37838: "typing.get_type_hints()" properly handles functions
  decorated with "functools.wraps()".

* bpo-38870: Expose "ast.unparse()" as a function of the "ast" module
  that can be used to unparse an "ast.AST" object and produce a string
  with code that would produce an equivalent "ast.AST" object when
  parsed. Patch by Pablo Galindo and Batuhan Taskaya.

* bpo-38859: AsyncMock now returns StopAsyncIteration on the
  exhaustion of a side_effects iterable. Since PEP-479 its Impossible
  to raise a StopIteration exception from a coroutine.

* bpo-38857: AsyncMock fix for return values that are awaitable types.
  This also covers side_effect iterable values that happened to be
  awaitable, and wraps callables that return an awaitable type. Before
  these awaitables were being awaited instead of being returned as is.

* bpo-38834: "typing.TypedDict" subclasses now track which keys are
  optional using the "__required_keys__" and "__optional_keys__"
  attributes, to enable runtime validation by downstream projects.
  Patch by Zac Hatfield-Dodds.

* bpo-38821: Fix unhandled exceptions in "argparse" when
  internationalizing error messages for arguments with "nargs" set to
  special (non-integer) values. Patch by Federico Bond.

* bpo-38820: Make Python compatible with OpenSSL 3.0.0.
  "ssl.SSLSocket.getpeercert()" no longer returns IPv6 addresses with
  a trailing new line.

* bpo-38811: Fix an unhandled exception in "pathlib" when "os.link()"
  is missing. Patch by Toke Høiland-Jørgensen.

* bpo-38686: Added support for multiple "qop" values in
  "urllib.request.AbstractDigestAuthHandler".

* bpo-38712: Add the Linux-specific "signal.pidfd_send_signal()"
  function, which allows sending a signal to a process identified by a
  file descriptor rather than a pid.

* bpo-38348: Add "-i" and "--indent" (indentation level), and "--no-
  type-comments" (type comments) command line options to ast parsing
  tool.

* bpo-37523: Change "zipfile.ZipExtFile" to raise "ValueError" when
  trying to access the underlying file object after it has been
  closed. This new behavior is consistent with how accessing closed
  files is handled in other parts of Python.

* bpo-38045: Improve the performance of "enum._decompose()" in "enum".
  Patch by hongweipeng.

* bpo-36820: Break cycle generated when saving an exception in
  socket.py, codeop.py and dyld.py as they keep alive not only the
  exception but user objects through the "__traceback__" attribute.
  Patch by Mario Corchero.

* bpo-36406: Handle namespace packages in "doctest". Patch by
  Karthikeyan Singaravelan.

* bpo-34776: Fix dataclasses to support forward references in type
  annotations

* bpo-20928: ElementTree supports recursive XInclude processing.
  Patch by Stefan Behnel.

* bpo-29636: Add whitespace options for formatting JSON with the
  "json.tool" CLI. The following mutually exclusive options are now
  supported: "--indent" for setting the indent level in spaces; "--
  tab" for indenting with tabs; "--no-indent" for suppressing
  newlines; and "--compact" for suppressing all whitespace. The
  default behavior remains the same as "--indent=4".


Documentation
-------------

* bpo-38928: Correct when venv’s "upgrade_dependencies()" and "--
  upgrade-deps" are added.

* bpo-38899: Update documentation to state that to activate virtual
  environments under fish one should use "source", not "" as
  documented at
  https://fishshell.com/docs/current/commands.html#source.

* bpo-22377: Improves documentation of the values that
  "datetime.datetime.strptime()" accepts for "%Z". Patch by Karl
  Dubost.


Tests
-----

* bpo-38546: Fix test_ressources_gced_in_workers() of
  test_concurrent_futures: explicitly stop the manager to prevent
  leaking a child process running in the background after the test
  completes.

* bpo-38546: Multiprocessing and concurrent.futures tests now stop the
  resource tracker process when tests complete.

* bpo-38614: Replace hardcoded timeout constants in tests with new
  "test.support" constants: "LOOPBACK_TIMEOUT", "INTERNET_TIMEOUT",
  "SHORT_TIMEOUT" and "LONG_TIMEOUT". It becomes easier to adjust
  these four timeout constants for all tests at once, rather than
  having to adjust every single test file.

* bpo-38547: Fix test_pty: if the process is the session leader,
  closing the master file descriptor raises a SIGHUP signal: simply
  ignore SIGHUP when running the tests.

* bpo-38992: Fix a test for "math.fsum()" that was failing due to
  constant folding.

* bpo-38991: "test.support": "run_python_until_end()",
  "assert_python_ok()" and "assert_python_failure()" functions no
  longer strip whitespaces from stderr. Remove
  "test.support.strip_python_stderr()" function.

* bpo-38965: Fix test_faulthandler on GCC 10. Use the “volatile”
  keyword in "faulthandler._stack_overflow()" to prevent tail call
  optimization on any compiler, rather than relying on compiler
  specific pragma.

* bpo-38875: test_capi: trashcan tests now require the test “cpu”
  resource.

* bpo-38841: Skip asyncio
  test_create_datagram_endpoint_existing_sock_unix on platforms
  lacking a functional bind() for named unix domain sockets.

* bpo-38692: Skip the test_posix.test_pidfd_open() test if
  "os.pidfd_open()" fails with a "PermissionError". This situation can
  happen in a Linux sandbox using a syscall whitelist which doesn’t
  allow the "pidfd_open()" syscall yet.

* bpo-38839: Fix some unused functions in tests. Patch by Adam
  Johnson.

* bpo-38669: Raise "TypeError" when passing target as a string with
  "unittest.mock.patch.object()".

* bpo-37957: test.regrtest now can receive a list of test patterns to
  ignore (using the -i/–ignore argument) or a file with a list of
  patterns to ignore (using the –ignore-file argument). Patch by Pablo
  Galindo.


Build
-----

* bpo-37404: "asyncio" now raises "TyperError" when calling
  incompatible methods with an "ssl.SSLSocket" socket.  Patch by Ido
  Michael.

* bpo-36500: Added an optional “regen” project to the Visual Studio
  solution that will regenerate all grammar, tokens, and opcodes.


Windows
-------

* bpo-39007: Add auditing events to functions in "winreg".

* bpo-33125: Add support for building and releasing Windows ARM64
  packages.


macOS
-----

* bpo-37931: Fixed a crash on OSX dynamic builds that occurred when
  re-initializing the posix module after a Py_Finalize if the
  environment had changed since the previous "import posix". Patch by
  Benoît Hudson.


IDLE
----

* bpo-38944: Escape key now closes IDLE completion windows.  Patch by
  Johnny Najera.

* bpo-38943: Fix IDLE autocomplete windows not always appearing on
  some systems. Patch by Johnny Najera.

* bpo-38862: ‘Strip Trailing Whitespace’ on the Format menu removes
  extra newlines at the end of non-shell files.

* bpo-38636: Fix IDLE Format menu tab toggle and file indent width.
  These functions (default shortcuts Alt-T and Alt-U) were mistakenly
  disabled in 3.7.5 and 3.8.0.


C API
-----

* bpo-38896: Remove "PyUnicode_ClearFreeList()" function: the Unicode
  free list has been removed in Python 3.3.

* bpo-37340: Remove "PyMethod_ClearFreeList()" and
  "PyCFunction_ClearFreeList()" functions: the free lists of bound
  method objects have been removed.

* bpo-38835: Exclude "PyFPE_START_PROTECT()" and "PyFPE_END_PROTECT()"
  macros of "pyfpe.h" from "Py_LIMITED_API" (stable API).


Python 3.9.0 alpha 1
====================

*Release date: 2019-11-19*


Security
--------

* bpo-38722: "runpy" now uses "io.open_code()" to open code files.
  Patch by Jason Killen.

* bpo-38622: Add additional audit events for the "ctypes" module.

* bpo-38418: Fixes audit event for "os.system()" to be named
  "os.system".

* bpo-38243: Escape the server title of
  "xmlrpc.server.DocXMLRPCServer" when rendering the document page as
  HTML. (Contributed by Dong-hee Na in bpo-38243.)

* bpo-38174: Update vendorized expat library version to 2.2.8, which
  resolves CVE-2019-15903.

* bpo-37764: Fixes email._header_value_parser.get_unstructured going
  into an infinite loop for a specific case in which the email header
  does not have trailing whitespace, and the case in which it contains
  an invalid encoded word. Patch by Ashwin Ramaswami.

* bpo-37461: Fix an infinite loop when parsing specially crafted email
  headers. Patch by Abhilash Raj.

* bpo-37363: Adds audit events for the range of supported run commands
  (see Command line and environment).

* bpo-37463: ssl.match_hostname() no longer accepts IPv4 addresses
  with additional text after the address and only quad-dotted notation
  without trailing whitespaces. Some inet_aton() implementations
  ignore whitespace and all data after whitespace, e.g. ‘127.0.0.1
  whatever’.

* bpo-37363: Adds audit events for "ensurepip", "ftplib", "glob",
  "imaplib", "nntplib", "pdb", "poplib", "shutil", "smtplib",
  "sqlite3", "subprocess", "telnetlib", "tempfile" and "webbrowser",
  as well as "os.listdir()", "os.scandir()" and "breakpoint()".

* bpo-37364: "io.open_code()" is now used when reading ".pth" files.

* bpo-34631: Updated OpenSSL to 1.1.1c in Windows installer

* bpo-34155: Fix parsing of invalid email addresses with more than one
  "@" (e.g. a@b@c.com.) to not return the part before 2nd "@" as valid
  email address. Patch by maxking & jpic.


Core and Builtins
-----------------

* bpo-38631: Replace "Py_FatalError()" call with a regular
  "RuntimeError" exception in "float.__getformat__()".

* bpo-38639: Optimized "math.floor()", "math.ceil()" and
  "math.trunc()" for floats.

* bpo-38640: Fixed a bug in the compiler that was causing to raise in
  the presence of break statements and continue statements inside
  always false while loops. Patch by Pablo Galindo.

* bpo-38613: Optimized some set operations (e.g. "|", "^", and "-") of
  "dict_keys". "d.keys() | other" was slower than "set(d) | other" but
  they are almost same performance for now.

* bpo-28029: """.replace("", s, n)" now returns "s" instead of an
  empty string for all non-zero "n".  There are similar changes for
  "bytes" and "bytearray" objects.

* bpo-38535: Fixed line numbers and column offsets for AST nodes for
  calls without arguments in decorators.

* bpo-38525: Fix a segmentation fault when using reverse iterators of
  empty "dict" objects. Patch by Dong-hee Na and Inada Naoki.

* bpo-38465: "bytearray", "array" and "mmap" objects allow now to
  export more than "2**31" buffers at a time.

* bpo-38469: Fixed a bug where the scope of named expressions was not
  being resolved correctly in the presence of the *global* keyword.
  Patch by Pablo Galindo.

* bpo-38437: Activate the "GC_DEBUG" macro for debug builds of the
  interpreter (when "Py_DEBUG" is set). Patch by Pablo Galindo.

* bpo-38379: When the garbage collector makes a collection in which
  some objects resurrect (they are reachable from outside the isolated
  cycles after the finalizers have been executed), do not block the
  collection of all objects that are still unreachable. Patch by Pablo
  Galindo and Tim Peters.

* bpo-38379: When cyclic garbage collection (gc) runs finalizers that
  resurrect unreachable objects, the current gc run ends, without
  collecting any cyclic trash.  However, the statistics reported by
  "collect()" and "get_stats()" claimed that all cyclic trash found
  was collected, and that the resurrected objects were collected.
  Changed the stats to report that none were collected.

* bpo-38392: In debug mode, "PyObject_GC_Track()" now calls
  "tp_traverse()" of the object type to ensure that the object is
  valid: test that objects visited by "tp_traverse()" are valid.

* bpo-38210: Remove unnecessary intersection and update set operation
  in dictview with empty set. (Contributed by Dong-hee Na in
  bpo-38210.)

* bpo-38402: Check the error from the system’s underlying "crypt" or
  "crypt_r".

* bpo-37474: On FreeBSD, Python no longer calls "fedisableexcept()" at
  startup to control the floating point control mode. The call became
  useless since FreeBSD 6: it became the default mode.

* bpo-38006: Fix a bug due to the interaction of weakrefs and the
  cyclic garbage collector. We must clear any weakrefs in garbage in
  order to prevent their callbacks from executing and causing a crash.

* bpo-38317: Fix warnings options priority: "PyConfig.warnoptions" has
  the highest priority, as stated in the **PEP 587**.

* bpo-38310: Predict "BUILD_MAP_UNPACK_WITH_CALL" ->
  "CALL_FUNCTION_EX" opcode pairs in the main interpreter loop. Patch
  by Brandt Bucher.

* bpo-36871: Improve error handling for the assert_has_calls and
  assert_has_awaits methods of mocks. Fixed a bug where any errors
  encountered while binding the expected calls to the mock’s spec were
  silently swallowed, leading to misleading error output.

* bpo-11410: Better control over symbol visibility is provided through
  use of the visibility attributes available in gcc >= 4.0, provided
  in a uniform way across POSIX and Windows. The POSIX build files
  have been updated to compile with -fvisibility=hidden, minimising
  exported symbols.

* bpo-38219: Optimized the "dict" constructor and the "update()"
  method for the case when the argument is a dict.

* bpo-38236: Python now dumps path configuration if it fails to import
  the Python codecs of the filesystem and stdio encodings.

* bpo-38013: Allow to call "async_generator_athrow().throw(...)" even
  for non-started async generator helper. It fixes annoying warning at
  the end of "asyncio.run()" call.

* bpo-38124: Fix an off-by-one error in PyState_AddModule that could
  cause out-of-bounds memory access.

* bpo-38116: The select module is now PEP-384 compliant and no longer
  has static state

* bpo-38113: ast module updated to PEP-384 and all statics removed

* bpo-38076: The struct module is now PEP-384 compatible

* bpo-38075: The random module is now PEP-384 compatible

* bpo-38074: zlib module made PEP-384 compatible

* bpo-38073: Make pwd extension module PEP-384 compatible

* bpo-38072: grp module made PEP-384 compatible

* bpo-38069: Make _posixsubprocess PEP-384 compatible

* bpo-38071: Make termios extension module PEP-384 compatible

* bpo-38005: Fixed comparing and creating of InterpreterID and
  ChannelID.

* bpo-36946: Fix possible signed integer overflow when handling
  slices. Patch by hongweipeng.

* bpo-37994: Fixed silencing arbitrary errors if an attribute lookup
  fails in several sites. Only AttributeError should be silenced.

* bpo-8425: Optimize set difference_update for the case when the other
  set is much larger than the base set.  (Suggested by Evgeny Kapun
  with code contributed by Michele Orrù).

* bpo-37966: The implementation of "is_normalized()" has been greatly
  sped up on strings that aren’t normalized, by implementing the full
  normalization-quick-check algorithm from the Unicode standard.

* bpo-37947: Adjust correctly the recursion level in the symtable
  generation for named expressions. Patch by Pablo Galindo.

* bpo-37812: The "CHECK_SMALL_INT" macro used inside
  "Object/longobject.c" has been replaced with an explicit "return" at
  each call site.

* bpo-37751: Fix "codecs.lookup()" to normalize the encoding name the
  same way than "encodings.normalize_encoding()", except that
  "codecs.lookup()" also converts the name to lower case.

* bpo-37830: Fixed compilation of "break" and "continue" in the
  "finally" block when the corresponding "try" block contains "return"
  with a non-constant value.

* bpo-20490: Improve import error message for partially initialized
  module on circular "from" imports - by Anthony Sottile.

* bpo-37840: Fix handling of negative indices in "sq_item" of
  "bytearray". Patch by Sergey Fedoseev.

* bpo-37802: Slightly improve performance of
  "PyLong_FromUnsignedLong()", "PyLong_FromUnsignedLongLong()" and
  "PyLong_FromSize_t()". Patch by Sergey Fedoseev.

* bpo-37409: Ensure explicit relative imports from interactive
  sessions and scripts (having no parent package) always raise
  ImportError, rather than treating the current module as the package.
  Patch by Ben Lewis.

* bpo-32912: Reverted bpo-32912: emitting "SyntaxWarning" instead of
  "DeprecationWarning" for invalid escape sequences in string and
  bytes literals.

* bpo-37757: **PEP 572**: As described in the PEP, assignment
  expressions now raise "SyntaxError" when their interaction with
  comprehension scoping results in an ambiguous target scope.

  The "TargetScopeError" subclass originally proposed by the PEP has
  been removed in favour of just raising regular syntax errors for the
  disallowed cases.

* bpo-36279: Fix potential use of uninitialized memory in
  "os.wait3()".

* bpo-36311: Decoding bytes objects larger than 2GiB is faster and no
  longer fails when a multibyte characters spans a chunk boundary.

* bpo-34880: The "assert" statement now works properly if the
  "AssertionError" exception is being shadowed. Patch by Zackery
  Spytz.

* bpo-37340: Removed object cache ("free_list") for bound method
  objects. Temporary bound method objects are less used than before
  thanks to the "LOAD_METHOD" opcode and the
  "_PyObject_VectorcallMethod" C API.

* bpo-37648: Fixed minor inconsistency in "list.__contains__()",
  "tuple.__contains__()" and a few other places. The collection’s item
  is now always at the left and the needle is on the right of "==".

* bpo-37444: Update differing exception between
  "builtins.__import__()" and "importlib.__import__()".

* bpo-37619: When adding a wrapper descriptor from one class to a
  different class (for example, setting "__add__ = str.__add__" on an
  "int" subclass), an exception is correctly raised when the operator
  is called.

* bpo-37593: Swap the positions of the *posonlyargs* and *args*
  parameters in the constructor of "ast.parameters" nodes.

* bpo-37543: Optimized pymalloc for non PGO build.

* bpo-37537: Compute allocated pymalloc blocks inside
  _Py_GetAllocatedBlocks().  This slows down _Py_GetAllocatedBlocks()
  but gives a small speedup to _PyObject_Malloc() and
  _PyObject_Free().

* bpo-37467: Fix "sys.excepthook()" and "PyErr_Display()" if a
  filename is a bytes string. For example, for a SyntaxError exception
  where the filename attribute is a bytes string.

* bpo-37433: Fix "SyntaxError" indicator printing too many spaces for
  multi-line strings - by Anthony Sottile.

* bpo-37417: "bytearray.extend()" now correctly handles errors that
  arise during iteration. Patch by Brandt Bucher.

* bpo-37414: The undocumented "sys.callstats()" function has been
  removed. Since Python 3.7, it was deprecated and always returned
  "None". It required a special build option "CALL_PROFILE" which was
  already removed in Python 3.7.

* bpo-37392: Remove "sys.getcheckinterval()" and
  "sys.setcheckinterval()" functions. They were deprecated since
  Python 3.2. Use "sys.getswitchinterval()" and
  "sys.setswitchinterval()" instead. Remove also "check_interval"
  field of the "PyInterpreterState" structure.

* bpo-37388: In development mode and in debug build, *encoding* and
  *errors* arguments are now checked on string encoding and decoding
  operations. Examples: "open()", "str.encode()" and "bytes.decode()".

  By default, for best performances, the *errors* argument is only
  checked at the first encoding/decoding error, and the *encoding*
  argument is sometimes ignored for empty strings.

* bpo-37348: Optimized decoding short ASCII string with UTF-8 and
  ascii codecs. "b"foo".decode()" is about 15% faster.  Patch by Inada
  Naoki.

* bpo-24214: Improved support of the surrogatepass error handler in
  the UTF-8 and UTF-16 incremental decoders.

* bpo-37330: "open()", "io.open()", "codecs.open()" and
  "fileinput.FileInput" no longer accept "'U'" (“universal newline”)
  in the file mode. This flag was deprecated since Python 3.3.

* bpo-35224: Reverse evaluation order of key: value in dict
  comprehensions as proposed in PEP 572. I.e. in "{k: v for ...}", "k"
  will be evaluated before "v".

* bpo-37316: Fix the "PySys_Audit()" call in "mmap.mmap".

* bpo-37300: Remove an unnecessary Py_XINCREF in classobject.c.

* bpo-37269: Fix a bug in the peephole optimizer that was not treating
  correctly constant conditions with binary operators. Patch by Pablo
  Galindo.

* bpo-20443: Python now gets the absolute path of the script filename
  specified on the command line (ex: “python3 script.py”): the
  __file__ attribute of the __main__ module and sys.path[0] become an
  absolute path, rather than a relative path.

* bpo-37257: Python’s small object allocator ("obmalloc.c") now allows
  (no more than) one empty arena to remain available for immediate
  reuse, without returning it to the OS.  This prevents thrashing in
  simple loops where an arena could be created and destroyed anew on
  each iteration.

* bpo-37231: The dispatching of type slots to special methods (for
  example calling "__mul__" when doing "x * y") has been made faster.

* bpo-36974: Implemented separate vectorcall functions for every
  calling convention of builtin functions and methods. This improves
  performance for calls.

* bpo-37213: Handle correctly negative line offsets in the peephole
  optimizer. Patch by Pablo Galindo.

* bpo-37219: Remove erroneous optimization for empty set differences.

* bpo-15913: Implement "PyBuffer_SizeFromFormat()" function
  (previously documented but not implemented): call
  "struct.calcsize()". Patch by Joannah Nanjekye.

* bpo-36922: Slot functions optimize any callable with
  "Py_TPFLAGS_METHOD_DESCRIPTOR" instead of only instances of
  "function".

* bpo-36974: The slot "tp_vectorcall_offset" is inherited
  unconditionally to support "super().__call__()" when the base class
  uses vectorcall.

* bpo-37160: "threading.get_native_id()" now also supports NetBSD.

* bpo-37077: Add "threading.get_native_id()" support for AIX. Patch by
  M. Felt

* bpo-36781: "sum()" has been optimized for boolean values.

* bpo-34556: Add "--upgrade-deps" to venv module. Patch by Cooper Ry
  Lees

* bpo-20523: "pdb.Pdb" supports ~/.pdbrc in Windows 7. Patch by Tim
  Hopper and Dan Lidral-Porter.

* bpo-35551: Updated encodings: - Removed the “tis260” encoding, which
  was an alias for the nonexistent “tactis” codec. - Added
  “mac_centeuro” as an alias for the mac_latin2 encoding.

* bpo-19072: The "classmethod" decorator can now wrap other
  descriptors such as property objects.  Adapted from a patch written
  by Graham Dumpleton.

* bpo-27575: Improve speed of dictview intersection by directly using
  set intersection logic. Patch by David Su.

* bpo-30773: Prohibit parallel running of aclose() / asend() /
  athrow(). Fix ag_running to reflect the actual running status of the
  AG.


Library
-------

* bpo-36589: The "curses.update_lines_cols()" function now returns
  "None" instead of "1" on success.

* bpo-38807: Update "TypeError" messages for "os.path.join()" to
  include "os.PathLike" objects as acceptable input types.

* bpo-38724: Add a repr for "subprocess.Popen" objects. Patch by
  Andrey Doroschenko.

* bpo-38786: pydoc now recognizes and parses HTTPS URLs. Patch by
  python273.

* bpo-38785: Prevent asyncio from crashing if parent "__init__" is not
  called from a constructor of object derived from "asyncio.Future".

* bpo-38723: "pdb" now uses "io.open_code()" to trigger auditing
  events.

* bpo-27805: Allow opening pipes and other non-seekable files in
  append mode with "open()".

* bpo-38438: Simplify the "argparse" usage message for "nargs="*"".

* bpo-38761: WeakSet is now registered as a
  collections.abc.MutableSet.

* bpo-38716: logging: change RotatingHandler namer and rotator to
  class-level attributes. This stops __init__ from setting them to
  None in the case where a subclass defines them with eponymous
  methods.

* bpo-38713: Add "os.P_PIDFD" constant, which may be passed to
  "os.waitid()" to wait on a Linux process file descriptor.

* bpo-38692: Add "asyncio.PidfdChildWatcher", a Linux-specific child
  watcher implementation that polls process file descriptors.

* bpo-38692: Expose the Linux "pidfd_open" syscall as
  "os.pidfd_open()".

* bpo-38602: Added constants "F_OFD_GETLK", "F_OFD_SETLK" and
  "F_OFD_SETLKW" to the "fcntl" module. Patch by Dong-hee Na.

* bpo-38334: Fixed seeking backward on an encrypted
  "zipfile.ZipExtFile".

* bpo-38312: Add "curses.get_escdelay()", "curses.set_escdelay()",
  "curses.get_tabsize()", and "curses.set_tabsize()" functions - by
  Anthony Sottile.

* bpo-38586: Now "fileConfig()" correctly sets the .name of handlers
  loaded.

* bpo-38565: Add new cache_parameters() method for
  functools.lru_cache() to better support pickling.

* bpo-34679: asynci.ProactorEventLoop.close() now only calls
  signal.set_wakeup_fd() in the main thread.

* bpo-31202: The case the result of "pathlib.WindowsPath.glob()"
  matches now the case of the pattern for literal parts.

* bpo-36321: Remove misspelled attribute.  The 3.8 changelog noted
  that this would be removed in 3.9.

* bpo-38521: Fixed erroneous equality comparison in
  statistics.NormalDist().

* bpo-38493: Added "CLD_KILLED" and "CLD_STOPPED" for "si_code". Patch
  by Dong-hee Na.

* bpo-38478: Fixed a bug in "inspect.signature.bind()" that was
  causing it to fail when handling a keyword argument with same name
  as positional-only parameter. Patch by Pablo Galindo.

* bpo-33604: Fixed "hmac.new" and "hmac.HMAC" to raise TypeError
  instead of ValueError when the digestmod parameter, now required in
  3.8, is omitted. Also clarified the hmac module documentation and
  docstrings.

* bpo-38378: Parameters *out* and *in* of "os.sendfile()" was renamed
  to *out_fd* and *in_fd*.

* bpo-38417: Added support for setting the umask in the child process
  to the subprocess module on POSIX systems.

* bpo-38449: Revert PR 15522, which introduces a regression in
  "mimetypes.guess_type()" due to improper handling of filenames as
  urls.

* bpo-38431: Fix "__repr__" method for "dataclasses.InitVar" to
  support typing objects, patch by Samuel Colvin.

* bpo-38109: Add missing "stat.S_IFDOOR", "stat.S_IFPORT",
  "stat.S_IFWHT", "stat.S_ISDOOR()", "stat.S_ISPORT()", and
  "stat.S_ISWHT()" values to the Python implementation of "stat".

* bpo-38422: Clarify docstrings of pathlib suffix(es)

* bpo-38405: Nested subclasses of "typing.NamedTuple" are now
  pickleable.

* bpo-38332: Prevent "KeyError" thrown by "_encoded_words.decode()"
  when given an encoded-word with invalid content-type encoding from
  propagating all the way to "email.message.get()".

* bpo-38371: Deprecated the "split()" method in "_tkinter.TkappType"
  in favour of the "splitlist()" method which has more consistent and
  predicable behavior.

* bpo-38341: Add "smtplib.SMTPNotSupportedError" to the "smtplib"
  exported names.

* bpo-38319: sendfile() used in socket and shutil modules was raising
  OverflowError for files >= 2GiB on 32-bit architectures.  (patch by
  Giampaolo Rodola)

* bpo-38242: Revert the new asyncio Streams API

* bpo-13153: OS native encoding is now used for converting between
  Python strings and Tcl objects.  This allows to display, copy and
  paste to clipboard emoji and other non-BMP characters.  Converting
  strings from Tcl to Python and back now never fails (except
  MemoryError).

* bpo-38019: Correctly handle pause/resume reading of closed asyncio
  unix pipe.

* bpo-38163: Child mocks will now detect their type as either
  synchronous or asynchronous, asynchronous child mocks will be
  AsyncMocks and synchronous child mocks will be either MagicMock or
  Mock (depending on their parent type).

* bpo-38161: Removes _AwaitEvent from AsyncMock.

* bpo-38216: Allow the rare code that wants to send invalid http
  requests from the "http.client" library a way to do so.  The fixes
  for bpo-30458 led to breakage for some projects that were relying on
  this ability to test their own behavior in the face of bad requests.

* bpo-28286: Deprecate opening "GzipFile" for writing implicitly.
  Always specify the *mode* argument for writing.

* bpo-38108: Any synchronous magic methods on an AsyncMock now return
  a MagicMock. Any asynchronous magic methods on a MagicMock now
  return an AsyncMock.

* bpo-38265: Update the *length* parameter of "os.pread()" to accept
  "Py_ssize_t" instead of "int".

* bpo-38112: "compileall" has a higher default recursion limit and new
  command-line arguments for path manipulation, symlinks handling, and
  multiple optimization levels.

* bpo-38248: asyncio: Fix inconsistent immediate Task cancellation

* bpo-38237: The arguments for the builtin pow function are more
  descriptive. They can now also be passed in as keywords.

* bpo-34002: Improve efficiency in parts of email package by changing
  while-pop to a for loop, using isdisjoint instead of set
  intersections.

* bpo-38191: Constructors of "NamedTuple" and "TypedDict" types now
  accept arbitrary keyword argument names, including “cls”, “self”,
  “typename”, “_typename”, “fields” and “_fields”.

* bpo-38155: Add "__all__" to  "datetime". Patch by Tahia Khan.

* bpo-38185: Fixed case-insensitive string comparison in "sqlite3.Row"
  indexing.

* bpo-38136: Changes AsyncMock call count and await count to be two
  different counters. Now await count only counts when a coroutine has
  been awaited, not when it has been called, and vice-versa. Update
  the documentation around this.

* bpo-37828: Fix default mock name in
  "unittest.mock.Mock.assert_called()" exceptions. Patch by Abraham
  Toriz Cruz.

* bpo-38175: Fix a memory leak in comparison of "sqlite3.Row" objects.

* bpo-33936: _hashlib no longer calls obsolete OpenSSL initialization
  function with OpenSSL 1.1.0+.

* bpo-34706: Preserve subclassing in inspect.Signature.from_callable.

* bpo-38153: Names of hashing algorithms from OpenSSL are now
  normalized to follow Python’s naming conventions. For example
  OpenSSL uses sha3-512 instead of sha3_512 or blake2b512 instead of
  blake2b.

* bpo-38115: Fix a bug in dis.findlinestarts() where it would return
  invalid bytecode offsets. Document that a code object’s co_lnotab
  can contain invalid bytecode offsets.

* bpo-38148: Add slots to "asyncio" transport classes, which can
  reduce memory usage.

* bpo-38142: The _hashlib OpenSSL wrapper extension module is now
  PEP-384 compliant.

* bpo-9216: hashlib constructors now support usedforsecurity flag to
  signal that a hashing algorithm is not used in a security context.

* bpo-36991: Fixes a potential incorrect AttributeError exception
  escaping ZipFile.extract() in some unsupported input error
  situations.

* bpo-38134: Remove obsolete copy of PBKDF2_HMAC_fast. All supported
  OpenSSL versions contain a fast implementation.

* bpo-38132: The OpenSSL hashlib wrapper uses a simpler
  implementation. Several Macros and pointless caches are gone. The
  hash name now comes from OpenSSL’s EVP. The algorithm name stays the
  same, except it is now always lower case.

* bpo-38008: Fix parent class check in protocols to correctly identify
  the module that provides a builtin protocol, instead of assuming
  they all come from the "collections.abc" module

* bpo-34037: For "asyncio", add a new coroutine
  "loop.shutdown_default_executor()". The new coroutine provides an
  API to schedule an executor shutdown that waits on the threadpool to
  finish closing. Also, "asyncio.run()" has been updated to utilize
  the new coroutine. Patch by Kyle Stanley.

* bpo-37405: Fixed regression bug for socket.getsockname() for non-
  CAN_ISOTP AF_CAN address family sockets by returning a 1-tuple
  instead of string.

* bpo-38121: Update parameter names on functions in importlib.metadata
  matching the changes in the 0.22 release of importlib_metadata.

* bpo-38110: The os.closewalk() implementation now uses the libc
  fdwalk() API on platforms where it is available.

* bpo-38093: Fixes AsyncMock so it doesn’t crash when used with
  AsyncContextManagers or AsyncIterators.

* bpo-37488: Add warning to "datetime.utctimetuple()",
  "datetime.utcnow()" and "datetime.utcfromtimestamp()" .

* bpo-35640: Allow passing a *path-like object* as "directory"
  argument to the "http.server.SimpleHTTPRequestHandler" class. Patch
  by Géry Ogam.

* bpo-38086: Update importlib.metadata with changes from
  importlib_metadata 0.21.

* bpo-37251: Remove "__code__" check in AsyncMock that incorrectly
  evaluated function specs as async objects but failed to evaluate
  classes with "__await__" but no "__code__" attribute defined as
  async objects.

* bpo-38037: Fix reference counters in the "signal" module.

* bpo-38066: Hide internal asyncio.Stream methods: feed_eof(),
  feed_data(), set_exception() and set_transport().

* bpo-38059: inspect.py now uses sys.exit() instead of exit()

* bpo-38049: Added command-line interface for the "ast" module.

* bpo-37953: In "typing", improved the "__hash__" and "__eq__" methods
  for "ForwardReferences".

* bpo-38026: Fixed "inspect.getattr_static()" used "isinstance" while
  it should avoid dynamic lookup.

* bpo-35923: Update "importlib.machinery.BuiltinImporter" to use
  "loader._ORIGIN" instead of a hardcoded value. Patch by Dong-hee Na.

* bpo-38010: In "importlib.metadata" sync with "importlib_metadata"
  0.20, clarifying behavior of "files()" and fixing issue where only
  one requirement was returned for "requires()" on "dist-info"
  packages.

* bpo-38006: weakref.WeakValueDictionary defines a local remove()
  function used as callback for weak references. This function was
  created with a closure. Modify the implementation to avoid the
  closure.

* bpo-37995: Added the *indent* option to "ast.dump()" which allows it
  to produce a multiline indented output.

* bpo-34410: Fixed a crash in the "tee()" iterator when re-enter it.
  RuntimeError is now raised in this case.

* bpo-37140: Fix a ctypes regression of Python 3.8. When a
  ctypes.Structure is passed by copy to a function, ctypes internals
  created a temporary object which had the side effect of calling the
  structure finalizer (__del__) twice. The Python semantics requires a
  finalizer to be called exactly once. Fix ctypes internals to no
  longer call the finalizer twice.

* bpo-37587: "_json.scanstring" is now up to 3x faster when there are
  many backslash escaped characters in the JSON string.

* bpo-37834: Prevent shutil.rmtree exception when built on non-Windows
  system without fd system call support, like older versions of macOS.

* bpo-10978: Semaphores and BoundedSemaphores can now release more
  than one waiting thread at a time.

* bpo-37972: Subscripts to the "unittest.mock.call" objects now
  receive the same chaining mechanism as any other custom attributes,
  so that the following usage no longer raises a "TypeError":

  call().foo().__getitem__(‘bar’)

  Patch by blhsing

* bpo-37965: Fix C compiler warning caused by
  distutils.ccompiler.CCompiler.has_function.

* bpo-37964: Add "F_GETPATH" command to "fcntl".

* bpo-37960: "repr()" of buffered and text streams now silences only
  expected exceptions when get the value of “name” and “mode”
  attributes.

* bpo-37961: Add a "total_nframe" field to the traces collected by the
  tracemalloc module. This field indicates the original number of
  frames before it was truncated.

* bpo-37951: Most features of the subprocess module now work again in
  subinterpreters. Only *preexec_fn* is restricted in subinterpreters.

* bpo-36205: Fix the rusage implementation of time.process_time() to
  correctly report the sum of the system and user CPU time.

* bpo-37950: Fix "ast.dump()" when call with incompletely initialized
  node.

* bpo-34679: Restores instantiation of Windows IOCP event loops from
  the non-main thread.

* bpo-36917: Add default implementation of the
  "ast.NodeVisitor.visit_Constant()" method which emits a deprecation
  warning and calls corresponding methody "visit_Num()",
  "visit_Str()", etc.

* bpo-37798: Update test_statistics.py to verify that the statistics
  module works well for both C and Python implementations. Patch by
  Dong-hee Na

* bpo-26589: Added a new status code to the http module: 451
  UNAVAILABLE_FOR_LEGAL_REASONS

* bpo-37915: Fix a segmentation fault that appeared when comparing
  instances of "datetime.timezone" and "datetime.tzinfo" objects.
  Patch by Pablo Galindo.

* bpo-32554: Deprecate having random.seed() call hash on arbitrary
  types.

* bpo-9938: Add optional keyword argument "exit_on_error" for
  "ArgumentParser".

* bpo-37851: The "faulthandler" module no longer allocates its
  alternative stack at Python startup. Now the stack is only allocated
  at the first faulthandler usage.

* bpo-32793: Fix a duplicated debug message when
  "smtplib.SMTP.connect()" is called.

* bpo-37885: venv: Don’t generate unset variable warning on
  deactivate.

* bpo-37868: Fix dataclasses.is_dataclass when given an instance that
  never raises AttributeError in __getattr__.  That is, an object that
  returns something for __dataclass_fields__ even if it’s not a
  dataclass.

* bpo-37811: Fix "socket" module’s "socket.connect(address)" function
  being unable to establish connection in case of interrupted system
  call. The problem was observed on all OSes which "poll(2)" system
  call can take only non-negative integers and -1 as a timeout value.

* bpo-37863: Optimizations for Fraction.__hash__ suggested by Tim
  Peters.

* bpo-21131: Fix "faulthandler.register(chain=True)" stack.
  faulthandler now allocates a dedicated stack of "SIGSTKSZ*2" bytes,
  instead of just "SIGSTKSZ" bytes. Calling the previous signal
  handler in faulthandler signal handler uses more than "SIGSTKSZ"
  bytes of stack memory on some platforms.

* bpo-37798: Add C fastpath for statistics.NormalDist.inv_cdf() Patch
  by Dong-hee Na

* bpo-37804: Remove the deprecated method
  "threading.Thread.isAlive()". Patch by Dong-hee Na.

* bpo-37819: Add Fraction.as_integer_ratio() to match the
  corresponding methods in bool, int, float, and decimal.

* bpo-14465: Add an xml.etree.ElementTree.indent() function for
  pretty-printing XML trees. Contributed by Stefan Behnel.

* bpo-37810: Fix "difflib" "?" hint in diff output when dealing with
  tabs.  Patch by Anthony Sottile.

* bpo-37772: In "zipfile.Path", when adding implicit dirs, ensure that
  ancestral directories are added and that duplicates are excluded.

* bpo-18578: Renamed and documented "test.bytecode_helper" as
  "test.support.bytecode_helper". Patch by Joannah Nanjekye.

* bpo-37785: Fix xgettext warnings in "argparse".

* bpo-34488: "writelines()" method of "io.BytesIO" is now slightly
  faster when many small lines are passed. Patch by Sergey Fedoseev.

* bpo-37449: "ensurepip" now uses "importlib.resources.read_binary()"
  to read data instead of "pkgutil.get_data()". Patch by Joannah
  Nanjekye.

* bpo-28292: Mark calendar.py helper functions as being private.  The
  follows PEP 8 guidance to maintain the style conventions in the
  module and it addresses a known case of user confusion.

* bpo-18049: Add definition of THREAD_STACK_SIZE for AIX in
  Python/thread_pthread.h The default thread stacksize caused crashes
  with the default recursion limit Patch by M Felt

* bpo-37742: The logging.getLogger() API now returns the root logger
  when passed the name ‘root’, whereas previously it returned a non-
  root logger named ‘root’. This could affect cases where user code
  explicitly wants a non-root logger named ‘root’, or instantiates a
  logger using logging.getLogger(__name__) in some top-level module
  called ‘root.py’.

* bpo-37738: Fix the implementation of curses "addch(str,
  color_pair)": pass the color pair to "setcchar()", instead of always
  passing 0 as the color pair.

* bpo-37723: Fix performance regression on regular expression parsing
  with huge character sets. Patch by Yann Vaginay.

* bpo-35943: The function "PyImport_GetModule()" now ensures any
  module it returns is fully initialized. Patch by Joannah Nanjekye.

* bpo-32178: Fix IndexError in "email" package when trying to parse
  invalid address fields starting with ":".

* bpo-37268: The "parser" module is deprecated and will be removed in
  future versions of Python.

* bpo-11953: Completing WSA* error codes in "socket".

* bpo-37685: Fixed comparisons of "datetime.timedelta" and
  "datetime.timezone".

* bpo-37697: Synchronize "importlib.metadata" with importlib_metadata
  0.19, improving handling of EGG-INFO files and fixing a crash when
  entry point names contained colons.

* bpo-37695: Correct "curses.unget_wch()" error message.  Patch by
  Anthony Sottile.

* bpo-37689: Add "is_relative_to()" in "PurePath" to determine whether
  or not one path is relative to another.

* bpo-29553: Fixed "argparse.ArgumentParser.format_usage()" for
  mutually exclusive groups. Patch by Andrew Nester.

* bpo-37691: Let math.dist() accept coordinates as sequences (or
  iterables) rather than just tuples.

* bpo-37685: Fixed "__eq__", "__lt__" etc implementations in some
  classes. They now return "NotImplemented" for unsupported type of
  the other operand. This allows the other operand to play role (for
  example the equality comparison with "ANY" will return "True").

* bpo-37354: Make Activate.ps1 Powershell script static to allow for
  signing it.

* bpo-37664: Update wheels bundled with ensurepip (pip 19.2.3 and
  setuptools 41.2.0)

* bpo-37663: Bring consistency to venv shell activation scripts by
  always using __VENV_PROMPT__.

* bpo-37642: Allowed the pure Python implementation of
  "datetime.timezone" to represent sub-minute offsets close to minimum
  and maximum boundaries, specifically in the ranges (23:59, 24:00)
  and (-23:59, 24:00). Patch by Ngalim Siregar

* bpo-36161: In "posix", use "ttyname_r" instead of "ttyname" for
  thread safety.

* bpo-36324: Make internal attributes for statistics.NormalDist()
  private.

* bpo-37555: Fix "NonCallableMock._call_matcher" returning tuple
  instead of "_Call" object when "self._spec_signature" exists. Patch
  by Elizabeth Uselton

* bpo-29446: Make "from tkinter import *" import only the expected
  objects.

* bpo-16970: Adding a value error when an invalid value in passed to
  nargs Patch by Robert Leenders

* bpo-34443: Exceptions from "enum" now use the "__qualname" of the
  enum class in the exception message instead of the "__name__".

* bpo-37491: Fix "IndexError" when parsing email headers with
  unexpectedly ending bare-quoted string value. Patch by Abhilash Raj.

* bpo-37587: Make json.loads faster for long strings. (Patch by Marco
  Paolini)

* bpo-18378: Recognize “UTF-8” as a valid value for LC_CTYPE in
  locale._parse_localename.

* bpo-37579: Return "NotImplemented" in Python implementation of
  "__eq__" for "timedelta" and "time" when the other object being
  compared is not of the same type to match C implementation. Patch by
  Karthikeyan Singaravelan.

* bpo-21478: Record calls to parent when autospecced object is
  attached to a mock using "unittest.mock.attach_mock()". Patch by
  Karthikeyan Singaravelan.

* bpo-37531: “python3 -m test -jN –timeout=TIMEOUT” now kills a worker
  process if it runs longer than *TIMEOUT* seconds.

* bpo-37482: Fix serialization of display name in originator or
  destination address fields with both encoded words and special
  chars.

* bpo-36993: Improve error reporting for corrupt zip files with bad
  zip64 extra data. Patch by Daniel Hillier.

* bpo-37502: pickle.loads() no longer raises TypeError when the
  buffers argument is set to None

* bpo-37520: Correct behavior for zipfile.Path.parent when the path
  object identifies a subdirectory.

* bpo-18374: Fix the ".col_offset" attribute of nested "ast.BinOp"
  instances which had a too large value in some situations.

* bpo-37424: Fixes a possible hang when using a timeout on
  "subprocess.run()" while capturing output.  If the child process
  spawned its own children or otherwise connected its stdout or stderr
  handles with another process, we could hang after the timeout was
  reached and our child was killed when attempting to read final
  output from the pipes.

* bpo-37421: Fix "multiprocessing.util.get_temp_dir()" finalizer:
  clear also the ‘tempdir’ configuration of the current process, so
  next call to "get_temp_dir()" will create a new temporary directory,
  rather than reusing the removed temporary directory.

* bpo-37481: The distutils "bdist_wininst" command is deprecated in
  Python 3.8, use "bdist_wheel" (wheel packages) instead.

* bpo-37479: When "Enum.__str__" is overridden in a derived class, the
  override will be used by "Enum.__format__" regardless of whether
  mixin classes are present.

* bpo-37440: http.client now enables TLS 1.3 post-handshake
  authentication for default context or if a cert_file is passed to
  HTTPSConnection.

* bpo-37437: Update vendorized expat version to 2.2.7.

* bpo-37428: SSLContext.post_handshake_auth = True no longer sets
  SSL_VERIFY_POST_HANDSHAKE verify flag for client connections.
  Although the option is documented as ignored for clients, OpenSSL
  implicitly enables cert chain validation when the flag is set.

* bpo-37420: "os.sched_setaffinity()" now correctly handles errors
  that arise during iteration over its "mask" argument. Patch by
  Brandt Bucher.

* bpo-37412: The "os.getcwdb()" function now uses the UTF-8 encoding
  on Windows, rather than the ANSI code page: see **PEP 529** for the
  rationale. The function is no longer deprecated on Windows.

* bpo-37406: The sqlite3 module now raises TypeError, rather than
  ValueError, if operation argument type is not str: execute(),
  executemany() and calling a connection.

* bpo-29412: Fix IndexError in parsing a header value ending
  unexpectedly. Patch by Abhilash Raj.

* bpo-36546: The *dist* argument for statistics.quantiles() is now
  positional only. The current name doesn’t reflect that the argument
  can be either a dataset or a distribution.  Marking the parameter as
  positional avoids confusion and makes it possible to change the name
  later.

* bpo-37394: Fix a bug that was causing the "queue" module to fail if
  the accelerator module was not available. Patch by Pablo Galindo.

* bpo-37376: "pprint" now has support for "types.SimpleNamespace".
  Patch by Carl Bordum Hansen.

* bpo-26967: An "ArgumentParser" with "allow_abbrev=False" no longer
  disables grouping of short flags, such as "-vv", but only disables
  abbreviation of long flags as documented. Patch by Zac Hatfield-
  Dodds.

* bpo-37212: "unittest.mock.call()" now preserves the order of keyword
  arguments in repr output. Patch by Karthikeyan Singaravelan.

* bpo-37372: Fix error unpickling datetime.time objects from Python 2
  with seconds>=24. Patch by Justin Blanchard.

* bpo-37345: Add formal support for UDPLITE sockets. Support was
  present before, but it is now easier to detect support with
  "hasattr(socket, 'IPPROTO_UDPLITE')" and there are constants defined
  for each of the values needed: "socket.IPPROTO_UDPLITE",
  "UDPLITE_SEND_CSCOV", and "UDPLITE_RECV_CSCOV". Patch by Gabe
  Appleton.

* bpo-37358: Optimized "functools.partial" by using vectorcall.

* bpo-37347: "sqlite3.Connection.create_aggregate()",
  "sqlite3.Connection.create_function()",
  "sqlite3.Connection.set_authorizer()",
  "sqlite3.Connection.set_progress_handler()"
  "sqlite3.Connection.set_trace_callback()" methods lead to segfaults
  if some of these methods are called twice with an equal object but
  not the same. Now callbacks are stored more carefully. Patch by
  Aleksandr Balezin.

* bpo-37163: The *obj* argument of "dataclasses.replace()" is
  positional-only now.

* bpo-37085: Add the optional Linux SocketCAN Broadcast Manager
  constants, used as flags to configure the BCM behaviour, in the
  socket module.  Patch by Karl Ding.

* bpo-37328: "HTMLParser.unescape" is removed.  It was undocumented
  and deprecated since Python 3.4.

* bpo-37305: Add .webmanifest -> application/manifest+json to list of
  recognized file types and content type headers

* bpo-37320: "aifc.openfp()" alias to "aifc.open()", "sunau.openfp()"
  alias to "sunau.open()", and "wave.openfp()" alias to "wave.open()"
  have been removed. They were deprecated since Python 3.7.

* bpo-37315: Deprecated accepting floats with integral value (like
  "5.0") in "math.factorial()".

* bpo-37312: "_dummy_thread" and "dummy_threading" modules have been
  removed. These modules were deprecated since Python 3.7 which
  requires threading support.

* bpo-33972: Email with single part but content-type set to
  "multipart/*" doesn’t raise AttributeError anymore.

* bpo-37280: Use threadpool for reading from file for sendfile
  fallback mode.

* bpo-37279: Fix asyncio sendfile support when sendfile sends extra
  data in fallback mode.

* bpo-19865: "ctypes.create_unicode_buffer()" now also supports non-
  BMP characters on platforms with 16-bit "wchar_t" (for example,
  Windows and AIX).

* bpo-37266: In a subinterpreter, spawning a daemon thread now raises
  an exception. Daemon threads were never supported in
  subinterpreters. Previously, the subinterpreter finalization crashed
  with a Python fatal error if a daemon thread was still running.

* bpo-37210: Allow pure Python implementation of "pickle" to work even
  when the C "_pickle" module is unavailable.

* bpo-21872: Fix "lzma": module decompresses data incompletely. When
  decompressing a FORMAT_ALONE format file, and it doesn’t have the
  end marker, sometimes the last one to dozens bytes can’t be output.
  Patch by Ma Lin.

* bpo-35922: Fix "RobotFileParser.crawl_delay()" and
  "RobotFileParser.request_rate()" to return "None" rather than raise
  "AttributeError" when no relevant rule is defined in the robots.txt
  file.  Patch by Rémi Lapeyre.

* bpo-35766: Change the format of feature_version to be a (major,
  minor) tuple.

* bpo-36607: Eliminate "RuntimeError" raised by "asyncio.all_tasks()"
  if internal tasks weak set is changed by another thread during
  iteration.

* bpo-18748: "_pyio.IOBase" destructor now does nothing if getting the
  "closed" attribute fails to better mimic "_io.IOBase" finalizer.

* bpo-36402: Fix a race condition at Python shutdown when waiting for
  threads. Wait until the Python thread state of all non-daemon
  threads get deleted (join all non-daemon threads), rather than just
  wait until non-daemon Python threads complete.

* bpo-37206: Default values which cannot be represented as Python
  objects no longer improperly represented as "None" in function
  signatures.

* bpo-37111: Added "encoding" and "errors" keyword parameters to
  "logging.basicConfig".

* bpo-12144: Ensure cookies with "expires" attribute are handled in
  "CookieJar.make_cookies()".

* bpo-34886: Fix an unintended ValueError from "subprocess.run()" when
  checking for conflicting "input" and "stdin" or "capture_output" and
  "stdout" or "stderr" args when they were explicitly provided but
  with "None" values within a passed in "**kwargs" dict rather than as
  passed directly by name. Patch contributed by Rémi Lapeyre.

* bpo-37173: The exception message for "inspect.getfile()" now
  correctly reports the passed class rather than the builtins module.

* bpo-37178: Give math.perm() a one argument form that means the same
  as math.factorial().

* bpo-37178: For math.perm(n, k), let k default to n, giving the same
  result as factorial.

* bpo-37165: Converted _collections._count_elements to use the
  Argument Clinic.

* bpo-34767: Do not always create a "collections.deque" in
  "asyncio.Lock".

* bpo-37158: Speed-up statistics.fmean() by switching from a function
  to a generator.

* bpo-34282: Remove "Enum._convert" method, deprecated in 3.8.

* bpo-37150: "argparse._ActionsContainer.add_argument" now throws
  error, if someone accidentally pass FileType class object instead of
  instance of FileType as "type" argument

* bpo-28724: The socket module now has the "socket.send_fds()" and
  "socket.recv.fds()" methods. Contributed by Joannah Nanjekye, Shinya
  Okano and Victor Stinner.

* bpo-35621: Support running asyncio subprocesses when execution event
  loop in a thread on UNIX.

* bpo-36520: Lengthy email headers with UTF-8 characters are now
  properly encoded when they are folded. Patch by Jeffrey Kintscher.

* bpo-30835: Fixed a bug in email parsing where a message with invalid
  bytes in content-transfer-encoding of a multipart message can cause
  an AttributeError. Patch by Andrew Donnellan.

* bpo-31163: pathlib.Path instance’s rename and replace methods now
  return the new Path instance.

* bpo-25068: "urllib.request.ProxyHandler" now lowercases the keys of
  the passed dictionary.

* bpo-26185: Fix "repr()" on empty "ZipInfo" object. Patch by Mickaël
  Schoentgen.

* bpo-21315: Email headers containing RFC2047 encoded words are parsed
  despite the missing whitespace, and a defect registered. Also
  missing trailing whitespace after encoded words is now registered as
  a defect.

* bpo-31904: Port test_datetime to VxWorks: skip zoneinfo tests on
  VxWorks

* bpo-35805: Add parser for Message-ID header and add it to default
  HeaderRegistry. This should prevent folding of Message-ID using RFC
  2048 encoded words.

* bpo-36871: Ensure method signature is used instead of constructor
  signature of a class while asserting mock object against method
  calls. Patch by Karthikeyan Singaravelan.

* bpo-35070: posix.getgrouplist() now works correctly when the user
  belongs to NGROUPS_MAX supplemental groups. Patch by Jeffrey
  Kintscher.

* bpo-31783: Fix race condition in ThreadPoolExecutor when worker
  threads are created during interpreter shutdown.

* bpo-36582: Fix "UserString.encode()" to correctly return "bytes"
  rather than a "UserString" instance.

* bpo-32424: Deprecate xml.etree.ElementTree.Element.copy() in favor
  of copy.copy().

  Patch by Gordon P. Hemsley

* bpo-36564: Fix infinite loop in email header folding logic that
  would be triggered when an email policy’s max_line_length is not
  long enough to include the required markup and any values in the
  message. Patch by Paul Ganssle

* bpo-36543: Removed methods Element.getchildren(),
  Element.getiterator() and ElementTree.getiterator() and the
  xml.etree.cElementTree module.

* bpo-36409: Remove the old plistlib API deprecated in Python 3.4

* bpo-36302: distutils sorts source file lists so that Extension .so
  files build more reproducibly by default

* bpo-36250: Ignore "ValueError" from "signal" with "interaction" in
  non-main thread.

* bpo-36046: Added "user", "group" and "extra_groups" parameters to
  the subprocess.Popen constructor. Patch by Patrick McLean.

* bpo-32627: Fix compile error when "_uuid" headers conflicting
  included.

* bpo-35800: Deprecate "smtpd.MailmanProxy" ready for future removal.

* bpo-35168: "shlex.shlex.punctuation_chars" is now a read-only
  property.

* bpo-8538: Add support for boolean actions like "--foo" and "--no-
  foo" to argparse. Patch contributed by Rémi Lapeyre.

* bpo-20504: Fixes a bug in "cgi" module when a multipart/form-data
  request has no "Content-Length" header.

* bpo-25988: The abstract base classes in "collections.abc" no longer
  are exposed in the regular "collections" module.

* bpo-11122: Distutils won’t check for rpmbuild in specified paths
  only.

* bpo-34775: Division handling of PurePath now returns NotImplemented
  instead of raising a TypeError when passed something other than an
  instance of str or PurePath. Patch by Roger Aiudi.

* bpo-34749: "binascii.a2b_base64()" is now up to 2 times faster.
  Patch by Sergey Fedoseev.

* bpo-34519: Add additional aliases for HP Roman 8. Patch by Michael
  Osipov.

* bpo-28009: Fix uuid.getnode() on platforms with ‘.’ as MAC Addr
  delimiter as well fix for MAC Addr format that omits a leading 0 in
  MAC Addr values. Currently, AIX is the only know platform with these
  settings. Patch by Michael Felt.

* bpo-30618: Add "readlink()". Patch by Girts Folkmanis.

* bpo-32498: Made "urllib.parse.unquote()" accept bytes in addition to
  strings. Patch by Stein Karlsen.

* bpo-33348: lib2to3 now recognizes expressions after "*" and "**"
  like in "f(*[] or [])".

* bpo-32689: Update "shutil.move()" function to allow for Path objects
  to be used as source argument. Patch by Emily Morehouse and Maxwell
  “5.13b” McKinnon.

* bpo-32820: Added __format__ to IPv4 and IPv6 classes.  Always
  outputs a fully zero- padded string. Supports b/x/n modifiers
  (bin/hex/native format).  Native format for IPv4 is bin, native
  format for IPv6 is hex. Also supports ‘#’ and ‘_’ modifiers.

* bpo-27657: Fix urllib.parse.urlparse() with numeric paths. A string
  like “path:80” is no longer parsed as a path but as a scheme
  (“path”) and a path (“80”).

* bpo-4963: Fixed non-deterministic behavior related to mimetypes
  extension mapping and module reinitialization.


Documentation
-------------

* bpo-21767: Explicitly mention abc support in
  functools.singledispatch

* bpo-38816: Provides more details about the interaction between
  "fork()" and CPython’s runtime, focusing just on the C-API.  This
  includes cautions about where "fork()" should and shouldn’t be
  called.

* bpo-38351: Modernize "email" examples from %-formatting to
  f-strings.

* bpo-38778: Document the fact that "RuntimeError" is raised if
  "os.fork()" is called in a subinterpreter.

* bpo-38592: Add Brazilian Portuguese to the language switcher at
  Python Documentation website.

* bpo-38294: Add list of no-longer-escaped chars to re.escape
  documentation

* bpo-38053: Modernized the plistlib documentation

* bpo-26868: Fix example usage of "PyModule_AddObject()" to properly
  handle errors.

* bpo-36797: Fix a dead link in the distutils API Reference.

* bpo-37977: Warn more strongly and clearly about pickle insecurity

* bpo-37979: Added a link to dateutil.parser.isoparse in the
  datetime.fromisoformat documentation. Patch by Paul Ganssle

* bpo-12707: Deprecate info(), geturl(), getcode() methods in favor of
  the headers, url, and status properties, respectively, for
  HTTPResponse and addinfourl. Also deprecate the code attribute of
  addinfourl in favor of the status attribute. Patch by Ashwin
  Ramaswami

* bpo-37937: Mention "frame.f_trace" in "sys.settrace()" docs.

* bpo-37878: Make "PyThreadState_DeleteCurrent()" Internal.

* bpo-37759: Beginning edits to Whatsnew 3.8

* bpo-37726: Stop recommending getopt in the tutorial for command line
  argument parsing and promote argparse.

* bpo-32910: Remove implementation-specific behaviour of how venv’s
  Deactivate works.

* bpo-37256: Fix wording of arguments for "Request" in
  "urllib.request"

* bpo-37284: Add a brief note to indicate that any new
  "sys.implementation" required attributes must go through the PEP
  process.

* bpo-30088: Documented that "mailbox.Maildir" constructor doesn’t
  attempt to verify the maildir folder layout correctness. Patch by
  Sviatoslav Sydorenko.

* bpo-37521: Fix "importlib" examples to insert any newly created
  modules via importlib.util.module_from_spec() immediately into
  sys.modules instead of after calling loader.exec_module().

  Thanks to Benjamin Mintz for finding the bug.

* bpo-37456: Slash (‘/’) is now part of syntax.

* bpo-37487: Fix PyList_GetItem index description to include 0.

* bpo-37149: Replace the dead link to the Tkinter 8.5 reference by
  John Shipman, New Mexico Tech, with a link to the archive.org copy.

* bpo-37478: Added possible exceptions to the description of
  os.chdir().

* bpo-34903: Documented that in "datetime.datetime.strptime()", the
  leading zero in some two-digit formats is optional. Patch by Mike
  Gleen.

* bpo-36260: Add decompression pitfalls to zipfile module
  documentation.

* bpo-37004: In the documentation for difflib, a note was added
  explicitly warning that the results of SequenceMatcher’s ratio
  method may depend on the order of the input strings.

* bpo-36960: Restructured the "datetime" docs in the interest of
  making them more user-friendly and improving readability. Patch by
  Brad Solomon.

* bpo-36487: Make C-API docs clear about what the “main” interpreter
  is.

* bpo-23460: The documentation for decimal string formatting using the
  ":g" specifier has been updated to reflect the correct exponential
  notation cutoff point. Original patch contributed by Tuomas Suutari.

* bpo-35803: Document and test that "tempfile" functions may accept a
  *path-like object* for the "dir" argument.  Patch by Anthony
  Sottile.

* bpo-33944: Added a note about the intended use of code in .pth
  files.

* bpo-34293: Fix the Doc/Makefile regarding PAPER environment variable
  and PDF builds

* bpo-25237: Add documentation for tkinter modules


Tests
-----

* bpo-38614: Fix test_communicate() of test_asyncio.test_subprocess:
  use "support.LONG_TIMEOUT" (5 minutes), instead of just 1 minute.

* bpo-38614: Add timeout constants to "test.support":
  "LOOPBACK_TIMEOUT", "INTERNET_TIMEOUT", "SHORT_TIMEOUT" and
  "LONG_TIMEOUT".

* bpo-38502: test.regrtest now uses process groups in the
  multiprocessing mode (-jN command line option) if process groups are
  available: if "os.setsid()" and "os.killpg()" functions are
  available.

* bpo-35998: Fix a race condition in
  test_asyncio.test_start_tls_server_1(). Previously, there was a race
  condition between the test main() function which replaces the
  protocol and the test ServerProto protocol which sends ANSWER once
  it gets HELLO. Now, only the test main() function is responsible to
  send data, ServerProto no longer sends data.

* bpo-38470: Fix "test_compileall.test_compile_dir_maxlevels()" on
  Windows without long path support: only create 3 subdirectories
  instead of between 20 and 100 subdirectories.

* bpo-37531: On timeout, regrtest no longer attempts to call
  "popen.communicate()" again: it can hang until all child processes
  using stdout and stderr pipes completes. Kill the worker process and
  ignores its output. Change also the faulthandler timeout of the main
  process from 1 minute to 5 minutes, for Python slowest buildbots.

* bpo-38239: Fix test_gdb for Link Time Optimization (LTO) builds.

* bpo-38275: test_ssl now handles disabled TLS/SSL versions better.
  OpenSSL’s crypto policy and run-time settings are recognized and
  tests for disabled versions are skipped. Tests also accept more TLS
  minimum_versions for platforms that override OpenSSL’s default with
  strict settings.

* bpo-38271: The private keys for test_ssl were encrypted with 3DES in
  traditional PKCS#5 format. 3DES and the digest algorithm of PKCS#5
  are blocked by some strict crypto policies. Use PKCS#8 format with
  AES256 encryption instead.

* bpo-38270: test.support now has a helper function to check for
  availability of a hash digest function. Several tests are refactored
  avoid MD5 and use SHA256 instead. Other tests are marked to use MD5
  and skipped when MD5 is disabled.

* bpo-37123: Multiprocessing test test_mymanager() now also expects
  -SIGTERM, not only exitcode 0. BaseManager._finalize_manager() sends
  SIGTERM to the manager process if it takes longer than 1 second to
  stop, which happens on slow buildbots.

* bpo-38212: Multiprocessing tests: increase
  test_queue_feeder_donot_stop_onexc() timeout from 1 to 60 seconds.

* bpo-38117: Test with OpenSSL 1.1.1d

* bpo-38018: Increase code coverage for multiprocessing.shared_memory.

* bpo-37805: Add tests for json.dump(…, skipkeys=True). Patch by Dong-
  hee Na.

* bpo-37531: Enhance regrtest multiprocess timeout: write a message
  when killing a worker process, catch popen.kill() and popen.wait()
  exceptions, put a timeout on the second call to popen.communicate().

* bpo-37876: Add tests for ROT-13 codec.

* bpo-36833: Added tests for PyDateTime_xxx_GET_xxx() macros of the C
  API of the "datetime" module. Patch by Joannah Nanjekye.

* bpo-37558: Fix test_shared_memory_cleaned_after_process_termination
  name handling

* bpo-37526: Add "test.support.catch_threading_exception()": context
  manager catching "threading.Thread" exception using
  "threading.excepthook()".

* bpo-37421: test_concurrent_futures now explicitly stops the
  ForkServer instance if it’s running.

* bpo-37421: multiprocessing tests now stop the ForkServer instance if
  it’s running: close the “alive” file descriptor to ask the server to
  stop and then remove its UNIX address.

* bpo-37421: test_distutils.test_build_ext() is now able to remove the
  temporary directory on Windows: don’t import the newly built C
  extension (“xx”) in the current process, but test it in a separated
  process.

* bpo-37421: test_concurrent_futures now cleans up multiprocessing to
  remove immediately temporary directories created by
  multiprocessing.util.get_temp_dir().

* bpo-37421: test_winconsoleio doesn’t leak a temporary file anymore:
  use tempfile.TemporaryFile() to remove it when the test completes.

* bpo-37421: multiprocessing tests now explicitly call
  "_run_finalizers()" to immediately remove temporary directories
  created by tests.

* bpo-37421: urllib.request tests now call "urlcleanup()" to remove
  temporary files created by "urlretrieve()" tests and to clear the
  "_opener" global variable set by "urlopen()" and functions calling
  indirectly "urlopen()".

* bpo-37472: Remove "Lib/test/outstanding_bugs.py".

* bpo-37199: Fix test failures when IPv6 is unavailable or disabled.

* bpo-19696: Replace deprecated method “random.choose” with
  “random.choice” in “test_pkg_import.py”.

* bpo-37335: Remove no longer necessary code from c locale coercion
  tests

* bpo-37421: Fix test_shutil to no longer leak temporary files.

* bpo-37411: Fix test_wsgiref.testEnviron() to no longer depend on the
  environment variables (don’t fail if “X” variable is set).

* bpo-37400: Fix test_os.test_chown(): use os.getgroups() rather than
  grp.getgrall() to get groups. Rename also the test to
  test_chown_gid().

* bpo-37359: Add –cleanup option to python3 -m test to remove
  "test_python_*" directories of previous failed jobs. Add “make
  cleantest” to run "python3 -m test --cleanup".

* bpo-37362: test_gdb no longer fails if it gets an “unexpected”
  message on stderr: it now ignores stderr. The purpose of test_gdb is
  to test that python-gdb.py commands work as expected, not to test
  gdb.

* bpo-35998: Avoid TimeoutError in test_asyncio:
  test_start_tls_server_1()

* bpo-37278: Fix test_asyncio ProactorLoopCtrlC: join the thread to
  prevent leaking a running thread and leaking a reference.

* bpo-37261: Fix "test.support.catch_unraisable_exception()": its
  __exit__() method now ignores unraisable exception raised when
  clearing its "unraisable" attribute.

* bpo-37069: regrtest now uses "sys.unraisablehook()" to mark a test
  as “environment altered” (ENV_CHANGED) if it emits an “unraisable
  exception”. Moreover, regrtest logs a warning in this case.

  Use "python3 -m test --fail-env-changed" to catch unraisable
  exceptions in tests.

* bpo-37252: Fix assertions in "test_close" and
  "test_events_mask_overflow" devpoll tests.

* bpo-37169: Rewrite "_PyObject_IsFreed()" unit tests.

* bpo-37153: "test_venv.test_multiprocessing()" now explicitly calls
  "pool.terminate()" to wait until the pool completes.

* bpo-34001: Make test_ssl pass with LibreSSL. LibreSSL handles
  minimum and maximum TLS version differently than OpenSSL.

* bpo-36919: Make "test_source_encoding.test_issue2301" implementation
  independent. The test will work now for both CPython and IronPython.

* bpo-30202: Update "test.test_importlib.test_abc" to test
  "find_spec()".

* bpo-28009: Modify the test_uuid logic to test when a program is
  available AND can be used to obtain a MACADDR as basis for an UUID.
  Patch by M. Felt

* bpo-34596: Fallback to a default reason when "unittest.skip()" is
  uncalled. Patch by Naitree Zhu.


Build
-----

* bpo-38809: On Windows, build scripts will now recognize and use
  python.exe from an active virtual env.

* bpo-38684: Fix _hashlib build when Blake2 is disabled, but OpenSSL
  supports it.

* bpo-38468: Misc/python-config.in now uses "getvar()" for all still
  existing "sysconfig.get_config_var()" calls. Patch by Joannah
  Nanjekye.

* bpo-37415: Fix stdatomic.h header check for ICC compiler: the ICC
  implementation lacks atomic_uintptr_t type which is needed by
  Python.

* bpo-38301: In Solaris family, we must be sure to use "-D_REENTRANT".
  Patch by Jesús Cea Avión.

* bpo-36002: Locate "llvm-profdata" and "llvm-ar" binaries using
  "AC_PATH_TOOL" rather than "AC_PATH_TARGET_TOOL".

* bpo-37936: The ".gitignore" file systematically keeps “rooted”, with
  a non-trailing slash, all the rules that are meant to apply to files
  in a specific place in the repo.  Previously, when the intended file
  to ignore happened to be at the root of the repo, we’d most often
  accidentally also ignore files and directories with the same name
  anywhere in the tree.

* bpo-37760: The "Tools/unicode/makeunicodedata.py" script, which is
  used for converting information from the Unicode Character Database
  into generated code and data used by the methods of "str" and by the
  "unicodedata" module, now handles each character’s data as a
  "dataclass" with named attributes, rather than a length-18 list of
  different fields.

* bpo-37936: The ".gitignore" file no longer applies to any files that
  are in fact tracked in the Git repository.  Patch by Greg Price.

* bpo-37725: Change “clean” makefile target to also clean the program
  guided optimization (PGO) data.  Previously you would have to use
  “make clean” and “make profile-removal”, or “make clobber”.

* bpo-37707: Mark some individual tests to skip when –pgo is used.
  The tests marked increase the PGO task time significantly and likely
  don’t help improve optimization of the final executable.

* bpo-36044: Reduce the number of unit tests run for the PGO
  generation task.  This speeds up the task by a factor of about 15x.
  Running the full unit test suite is slow.  This change may result in
  a slightly less optimized build since not as many code branches will
  be executed.  If you are willing to wait for the much slower build,
  the old behavior can be restored using ‘./configure [..]
  PROFILE_TASK=”-m test –pgo-extended”’. We make no guarantees as to
  which PGO task set produces a faster build. Users who care should
  run their own relevant benchmarks as results can depend on the
  environment, workload, and compiler tool chain.

* bpo-37468: "make install" no longer installs "wininst-*.exe" files
  used by distutils bdist_wininst: bdist_wininst only works on
  Windows.

* bpo-37189: Many "PyRun_XXX()" functions like "PyRun_String()" were
  no longer exported in "libpython38.dll" by mistake. Export them
  again to fix the ABI compatibility.

* bpo-25361: Enables use of SSE2 instructions in Windows 32-bit build.

* bpo-36210: Update optional extension module detection for AIX.
  ossaudiodev and spwd are not applicable for AIX, and are no longer
  reported as missing. 3rd-party packaging of ncurses (with ASIS
  support) conflicts with officially supported AIX curses library, so
  configure AIX to use libcurses.a. However, skip trying to build
  _curses_panel.

  patch by M Felt


Windows
-------

* bpo-38589: Fixes HTML Help shortcut when Windows is not installed to
  C drive

* bpo-38453: Ensure ntpath.realpath() correctly resolves relative
  paths.

* bpo-38519: Restores the internal C headers that were missing from
  the nuget.org and Microsoft Store packages.

* bpo-38492: Remove "pythonw.exe" dependency on the Microsoft C++
  runtime.

* bpo-38344: Fix error message in activate.bat

* bpo-38359: Ensures "pyw.exe" launcher reads correct registry key.

* bpo-38355: Fixes "ntpath.realpath" failing on "sys.executable".

* bpo-38117: Update bundled OpenSSL to 1.1.1d

* bpo-38092: Reduce overhead when using multiprocessing in a Windows
  virtual environment.

* bpo-38133: Allow py.exe launcher to locate installations from the
  Microsoft Store and improve display of active virtual environments.

* bpo-38114: The "pip.ini" is no longer included in the Nuget package.

* bpo-32592: Set Windows 8 as the minimum required version for API
  support

* bpo-36634: "os.cpu_count()" now returns active processors rather
  than maximum processors.

* bpo-36634: venv activate.bat now works when the existing variables
  contain double quote characters.

* bpo-38081: Prevent error calling "os.path.realpath()" on "'NUL'".

* bpo-38087: Fix case sensitivity in test_pathlib and test_ntpath.

* bpo-38088: Fixes distutils not finding vcruntime140.dll with only
  the v142 toolset installed.

* bpo-37283: Ensure command-line and unattend.xml setting override
  previously detected states in Windows installer.

* bpo-38030: Fixes "os.stat()" failing for block devices on Windows

* bpo-38020: Fixes potential crash when calling "os.readlink()" (or
  indirectly through "realpath()") on a file that is not a supported
  link.

* bpo-37705: Improve the implementation of "winerror_to_errno()".

* bpo-37549: "os.dup()" no longer fails for standard streams on
  Windows 7.

* bpo-1311: The "nul" file on Windows now returns True from "exists()"
  and a valid result from "os.stat()" with "S_IFCHR" set.

* bpo-9949: Enable support for following symlinks in "os.realpath()".

* bpo-37834: Treat all name surrogate reparse points on Windows in
  "os.lstat()" and other reparse points as regular files in
  "os.stat()".

* bpo-36266: Add the module name in the formatted error message when
  DLL load fail happens during module import in
  "_PyImport_FindSharedFuncptrWindows()". Patch by Srinivas Nyayapati.

* bpo-25172: Trying to import the "crypt" module on Windows will
  result in an "ImportError" with a message explaining that the module
  isn’t supported on Windows. On other platforms, if the underlying
  "_crypt" module is not available, the ImportError will include a
  message explaining the problem.

* bpo-37778: Fixes the icons used for file associations to the
  Microsoft Store package.

* bpo-37734: Fix use of registry values to launch Python from
  Microsoft Store app.

* bpo-37702: Fix memory leak on Windows in creating an SSLContext
  object or running urllib.request.urlopen(’https://…’).

* bpo-37672: Switch Windows Store package’s pip to use bundled
  "pip.ini" instead of "PIP_USER" variable.

* bpo-10945: Officially drop support for creating bdist_wininst
  installers on non-Windows systems.

* bpo-37445: Include the "FORMAT_MESSAGE_IGNORE_INSERTS" flag in
  "FormatMessageW()" calls.

* bpo-37369: Fixes path for "sys.executable" when running from the
  Microsoft Store.

* bpo-37380: Don’t collect unfinished processes with
  "subprocess._active" on Windows to cleanup later. Patch by Ruslan
  Kuprieiev.

* bpo-37351: Removes libpython38.a from standard Windows distribution.

* bpo-35360: Update Windows builds to use SQLite 3.28.0.

* bpo-37267: On Windows, "os.dup()" no longer creates an inheritable
  fd when handling a character file.

* bpo-36779: Ensure "time.tzname" is correct on Windows when the
  active code page is set to CP_UTF7 or CP_UTF8.

* bpo-32587: Make "winreg.REG_MULTI_SZ" support zero-length strings.

* bpo-28269: Replace use of "strcasecmp()" for the system function
  "_stricmp()". Patch by Minmin Gong.

* bpo-36590: Add native Bluetooth RFCOMM support to socket module.


macOS
-----

* bpo-38117: Updated OpenSSL to 1.1.1d in macOS installer.

* bpo-38089: Move Azure Pipelines to latest VM versions and make macOS
  tests optional

* bpo-18049: Increase the default stack size of threads from 5MB to
  16MB on macOS, to match the stack size of the main thread. This
  avoids crashes on deep recursion in threads.

* bpo-34602: Avoid test suite failures on macOS by no longer calling
  resource.setrlimit to increase the process stack size limit at
  runtime. The runtime change is no longer needed since the
  interpreter is being built with a larger default stack size.

* bpo-35360: Update macOS installer to use SQLite 3.28.0.

* bpo-34631: Updated OpenSSL to 1.1.1c in macOS installer.


IDLE
----

* bpo-26353: Stop adding newline when saving an IDLE shell window.

* bpo-4630: Add an option to toggle IDLE’s cursor blink for shell,
  editor, and output windows.  See Settings, General, Window
  Preferences, Cursor Blink. Patch by Zackery Spytz.

* bpo-38598: Do not try to compile IDLE shell or output windows

* bpo-36698: IDLE no longer fails when write non-encodable characters
  to stderr.  It now escapes them with a backslash, as the regular
  Python interpreter. Added the "errors" field to the standard
  streams.

* bpo-35379: When exiting IDLE, catch any AttributeError.  One happens
  when EditorWindow.close is called twice.  Printing a traceback, when
  IDLE is run from a terminal, is useless and annoying.

* bpo-38183: To avoid problems, test_idle ignores the user config
  directory. It no longer tries to create or access .idlerc or any
  files within. Users must run IDLE to discover problems with saving
  settings.

* bpo-38077: IDLE no longer adds ‘argv’ to the user namespace when
  initializing it.  This bug only affected 3.7.4 and 3.8.0b2 to
  3.8.0b4.

* bpo-38041: Shell restart lines now fill the window width, always
  start with ‘=’, and avoid wrapping unnecessarily. The line will
  still wrap if the included file name is long relative to the width.

* bpo-35771: To avoid occasional spurious test_idle failures on slower
  machines, increase the "hover_delay" in test_tooltip.

* bpo-37824: Properly handle user input warnings in IDLE shell. Cease
  turning SyntaxWarnings into SyntaxErrors.

* bpo-37929: IDLE Settings dialog now closes properly when there is no
  shell window.

* bpo-37902: Add mousewheel scrolling for IDLE module, path, and stack
  browsers. Patch by George Zhang.

* bpo-37849: Fixed completions list appearing too high or low when
  shown above the current line.

* bpo-36419: Refactor IDLE autocomplete and improve testing.

* bpo-37748: Reorder the Run menu.  Put the most common choice, Run
  Module, at the top.

* bpo-37692: Improve highlight config sample with example shell
  interaction and better labels for shell elements.

* bpo-37628: Settings dialog no longer expands with font size.

* bpo-37627: Initialize the Customize Run dialog with the command line
  arguments most recently entered before.  The user can optionally
  edit before submitting them.

* bpo-33610: Fix code context not showing the correct context when
  first toggled on.

* bpo-37530: Optimize code context to reduce unneeded background
  activity. Font and highlight changes now occur along with text
  changes instead of after a random delay.

* bpo-27452: Cleanup "config.py" by inlining "RemoveFile" and
  simplifying the handling of "file" in "CreateConfigHandlers".

* bpo-37325: Fix tab focus traversal order for help source and custom
  run dialogs.

* bpo-37321: Both subprocess connection error messages now refer to
  the ‘Startup failure’ section of the IDLE doc.

* bpo-17535: Add optional line numbers for IDLE editor windows.
  Windows open without line numbers unless set otherwise in the
  General tab of the configuration dialog.

* bpo-26806: To compensate for stack frames added by IDLE and avoid
  possible problems with low recursion limits, add 30 to limits in the
  user code execution process.  Subtract 30 when reporting recursion
  limits to make this addition mostly transparent.

* bpo-37177: Properly ‘attach’ search dialogs to their main window so
  that they behave like other dialogs and do not get hidden behind
  their main window.

* bpo-37039: Adjust “Zoom Height” to individual screens by momentarily
  maximizing the window on first use with a particular screen.
  Changing screen settings may invalidate the saved height.  While a
  window is maximized, “Zoom Height” has no effect.

* bpo-35763: Make calltip reminder about ‘/’ meaning positional-only
  less obtrusive by only adding it when there is room on the first
  line.

* bpo-5680: Add ‘Run… Customized’ to the Run menu to run a module with
  customized settings.  Any ‘command line arguments’ entered are added
  to sys.argv. One can suppress the normal Shell main module restart.

* bpo-36390: Gather Format menu functions into format.py.  Combine
  paragraph.py, rstrip.py, and format methods from editor.py.


Tools/Demos
-----------

* bpo-38118: Update Valgrind suppression file to ignore a false alarm
  in "PyUnicode_Decode()" when using GCC builtin strcmp().

* bpo-38347: pathfix.py: Assume all files that end on ‘.py’ are Python
  scripts when working recursively.

* bpo-37803: pdb’s "--help" and "--version" long options now work.

* bpo-37942: Improve ArgumentClinic converter for floats.

* bpo-37704: Remove "Tools/scripts/h2py.py": use cffi to access a C
  API in Python.

* bpo-37675: 2to3 now works when run from a zipped standard library.

* bpo-37034: Argument Clinic now uses the argument name on errors with
  keyword-only argument instead of their position. Patch contributed
  by Rémi Lapeyre.

* bpo-37064: Add option -k to pathscript.py script: preserve shebang
  flags. Add option -a to pathscript.py script: add flags.


C API
-----

* bpo-37633: Re-export some function compatibility wrappers for macros
  in "pythonrun.h".

* bpo-38644: Provide "Py_EnterRecursiveCall()" and
  "Py_LeaveRecursiveCall()" as regular functions for the limited API.
  Previously, there were defined as macros, but these macros didn’t
  work with the limited API which cannot access
  "PyThreadState.recursion_depth" field. Remove
  "_Py_CheckRecursionLimit" from the stable ABI.

* bpo-38650: The global variable "PyStructSequence_UnnamedField" is
  now a constant and refers to a constant string.

* bpo-38540: Fixed possible leak in "PyArg_Parse()" and similar
  functions for format units ""es#"" and ""et#"" when the macro
  "PY_SSIZE_T_CLEAN" is not defined.

* bpo-38395: Fix a crash in "weakref.proxy" objects due to incorrect
  lifetime management when calling some associated methods that may
  delete the last reference to object being referenced by the proxy.
  Patch by Pablo Galindo.

* bpo-36389: The "_PyObject_CheckConsistency()" function is now also
  available in release mode. For example, it can be used to debug a
  crash in the "visit_decref()" function of the GC.

* bpo-38266: Revert the removal of PyThreadState_DeleteCurrent() with
  documentation.

* bpo-38303: Update audioop extension module to use the stable ABI
  (PEP-384). Patch by Tyler Kieft.

* bpo-38234: "Py_SetPath()" now sets "sys.executable" to the program
  full path ("Py_GetProgramFullPath()") rather than to the program
  name ("Py_GetProgramName()").

* bpo-38234: Python ignored arguments passed to "Py_SetPath()",
  "Py_SetPythonHome()" and "Py_SetProgramName()": fix Python
  initialization to use specified arguments.

* bpo-38205: The "Py_UNREACHABLE()" macro now calls "Py_FatalError()".

* bpo-38140: Make dict and weakref offsets opaque for C heap types by
  passing the offsets through PyMemberDef

* bpo-15088: The C function "PyGen_NeedsFinalizing" has been removed.
  It was not documented, tested or used anywhere within CPython after
  the implementation of **PEP 442**. Patch by Joannah Nanjekye. (Patch
  by Joannah Nanjekye)

* bpo-36763: Options added by "PySys_AddXOption()" are now handled the
  same way than "PyConfig.xoptions" and command line "-X" options.

* bpo-37926: Fix a crash in "PySys_SetArgvEx(0, NULL, 0)".

* bpo-37879: Fix subtype_dealloc to suppress the type decref when the
  base type is a C heap type

* bpo-37645: Add "_PyObject_FunctionStr()" to get a user-friendly
  string representation of a function-like object. Patch by Jeroen
  Demeyer.

* bpo-29548: The functions "PyEval_CallObject", "PyEval_CallFunction",
  "PyEval_CallMethod" and "PyEval_CallObjectWithKeywords" are
  deprecated. Use "PyObject_Call()" and its variants instead.

* bpo-37151: "PyCFunction_Call" is now a deprecated alias of
  "PyObject_Call()".

* bpo-37540: The vectorcall protocol now requires that the caller
  passes only strings as keyword names.

* bpo-37207: The vectorcall protocol is now enabled for "type"
  objects: set "tp_vectorcall" to a vectorcall function to be used
  instead of "tp_new" and "tp_init" when calling the class itself.

* bpo-21120: Exclude Python-ast.h, ast.h and asdl.h from the limited
  API.

* bpo-37483: Add new function "_PyObject_CallOneArg" for calling an
  object with one positional argument.

* bpo-36763: Add "PyConfig_SetWideStringList()" function.

* bpo-37337: Add fast functions for calling methods:
  "_PyObject_VectorcallMethod()", "_PyObject_CallMethodNoArgs()" and
  "_PyObject_CallMethodOneArg()".

* bpo-28805: The "METH_FASTCALL" calling convention has been
  documented.

* bpo-37221: The new function "PyCode_NewWithPosOnlyArgs()" allows to
  create code objects like "PyCode_New()", but with an extra
  *posonlyargcount* parameter for indicating the number of positonal-
  only arguments.

* bpo-37215: Fix dtrace issue introduce by bpo-36842

* bpo-37194: Add a new public "PyObject_CallNoArgs()" function to the
  C API: call a callable Python object without any arguments. It is
  the most efficient way to call a callback without any argument. On
  x86-64, for example, "PyObject_CallFunctionObjArgs(func, NULL)"
  allocates 960 bytes on the stack per call, whereas
  "PyObject_CallNoArgs(func)" only allocates 624 bytes per call.

* bpo-37170: Fix the cast on error in
  "PyLong_AsUnsignedLongLongMask()".

* bpo-35381: Convert posixmodule.c statically allocated types
  "DirEntryType" and "ScandirIteratorType" to heap-allocated types.

* bpo-34331: Use singular/plural noun in error message when
  instantiating an abstract class with non-overriden abstract
  method(s).


Python 3.8.0 beta 1
===================

*Release date: 2019-06-04*


Security
--------

* bpo-35907: CVE-2019-9948: Avoid file reading by disallowing "local-
  file://" and "local_file://" URL schemes in "URLopener().open()" and
  "URLopener().retrieve()" of "urllib.request".

* bpo-33529: Prevent fold function used in email header encoding from
  entering infinite loop when there are too many non-ASCII characters
  in a header.

* bpo-33164: Updated blake2 implementation which uses secure memset
  implementation provided by platform.


Core and Builtins
-----------------

* bpo-35814: Allow unpacking in the right hand side of annotated
  assignments. In particular, "t: Tuple[int, ...] = x, y, *z" is now
  allowed.

* bpo-37126: All structseq objects are now tracked by the garbage
  collector. Patch by Pablo Galindo.

* bpo-37122: Make the *co_argcount* attribute of code objects
  represent the total number of positional arguments (including
  positional-only arguments). The value of *co_posonlyargcount* can be
  used to distinguish which arguments are positional only, and the
  difference (*co_argcount* - *co_posonlyargcount*) is the number of
  positional-or-keyword arguments. Patch by Pablo Galindo.

* bpo-20092: Constructors of "int", "float" and "complex" will now use
  the "__index__()" special method, if available and the corresponding
  method "__int__()", "__float__()" or "__complex__()" is not
  available.

* bpo-37087: Add native thread ID (TID) support to OpenBSD.

* bpo-26219: Implemented per opcode cache mechanism and "LOAD_GLOBAL"
  instruction use it. "LOAD_GLOBAL" is now about 40% faster.
  Contributed by Yury Selivanov, and Inada Naoki.

* bpo-37072: Fix crash in PyAST_FromNodeObject() when flags is NULL.

* bpo-37029: Freeing a great many small objects could take time
  quadratic in the number of arenas, due to using linear search to
  keep "obmalloc.c"’s list of usable arenas sorted by order of number
  of free memory pools. This is accomplished without search now,
  leaving the worst-case time linear in the number of arenas.  For
  programs where this quite visibly matters (typically with more than
  100 thousand small objects alive simultaneously), this can greatly
  reduce the time needed to release their memory.

* bpo-26423: Fix possible overflow in "wrap_lenfunc()" when
  "sizeof(long) < sizeof(Py_ssize_t)" (e.g., 64-bit Windows).

* bpo-37050: Improve the AST for “debug” f-strings, which use ‘=’ to
  print out the source of the expression being evaluated.  Delete
  expr_text from the FormattedValue node, and instead use a Constant
  string node (possibly merged with adjacent constant expressions
  inside the f-string).

* bpo-22385: The "bytes.hex", "bytearray.hex", and "memoryview.hex"
  methods as well as the "binascii.hexlify" and "b2a_hex" functions
  now have the ability to include an optional separator between hex
  bytes.  This functionality was inspired by MicroPython’s hexlify
  implementation.

* bpo-26836: Add "os.memfd_create()".

* bpo-37032: Added new "replace()" method to the code type
  ("types.CodeType").

* bpo-37007: Implement "socket.if_nameindex()",
  "socket.if_nametoindex()", and "socket.if_indextoname()" on Windows.

* bpo-36829: "PyErr_WriteUnraisable()" now creates a traceback object
  if there is no current traceback. Moreover, call
  "PyErr_NormalizeException()" and "PyException_SetTraceback()" to
  normalize the exception value. Ignore any error.

* bpo-36878: Only accept text after "# type: ignore" if the first
  character is ASCII. This is to disallow things like "# type:
  ignoreé".

* bpo-36878: Store text appearing after a "# type: ignore" comment in
  the AST. For example a type ignore like "# type: ignore[E1000]" will
  have the string ""[E1000]"" stored in its AST node.

* bpo-2180: Treat line continuation at EOF as a "SyntaxError" by
  Anthony Sottile.

* bpo-36907: Fix a crash when calling a C function with a keyword dict
  ("f(**kwargs)") and changing the dict "kwargs" while that function
  is running.

* bpo-36946: Fix possible signed integer overflow when handling
  slices.

* bpo-36826: Add NamedExpression kind support to ast_unparse.c

* bpo-1875: A "SyntaxError" is now raised if a code blocks that will
  be optimized away (e.g. if conditions that are always false)
  contains syntax errors. Patch by Pablo Galindo.

* bpo-36027: Allow computation of modular inverses via three-argument
  "pow": the second argument is now permitted to be negative in the
  case where the first and third arguments are relatively prime.

* bpo-36861: Update the Unicode database to version 12.1.0.

* bpo-28866: Avoid caching attributes of classes which type defines
  mro() to avoid a hard cache invalidation problem.

* bpo-36851: The "FrameType" stack is now correctly cleaned up if the
  execution ends with a return and the stack is not empty.

* bpo-34616: The "compile()" builtin functions now support the
  "ast.PyCF_ALLOW_TOP_LEVEL_AWAIT" flag,  which allow to compile
  sources that  contains top-level "await", "async with" or "async
  for". This is useful to evaluate async-code from with an already
  async functions; for example in a custom REPL.

* bpo-36842: Implement PEP 578, adding sys.audit, io.open_code and
  related APIs.

* bpo-27639: Correct return type for UserList slicing operations.
  Patch by Michael Blahay, Erick Cervantes, and vaultah

* bpo-36737: Move PyRuntimeState.warnings into per-interpreter state
  (via “module state”).

* bpo-36793: Removed "__str__" implementations from builtin types
  "bool", "int", "float", "complex" and few classes from the standard
  library. They now inherit "__str__()" from "object".

* bpo-36817: Add a "=" feature f-strings for debugging. This can
  precede "!s", "!r", or "!a". It produces the text of the expression,
  followed by an equal sign, followed by the repr of the value of the
  expression. So "f'{3*9+15=}'" would be equal to the string
  "'3*9+15=42'".  If "=" is specified, the default conversion is set
  to "!r", unless a format spec is given, in which case the formatting
  behavior is unchanged, and __format__ will be used.

* bpo-24048: Save the live exception during import.c’s
  "remove_module()".

* bpo-27987: pymalloc returns memory blocks aligned by 16 bytes,
  instead of 8 bytes, on 64-bit platforms to conform x86-64 ABI.
  Recent compilers assume this alignment more often. Patch by Inada
  Naoki.

* bpo-36601: A long-since-meaningless check for "getpid() == main_pid"
  was removed from Python’s internal C signal handler.

* bpo-36594: Fix incorrect use of "%p" in format strings. Patch by
  Zackery Spytz.

* bpo-36045: builtins.help() now prefixes "async" for async functions

* bpo-36084: Add native thread ID (TID) to threading.Thread objects
  (supported platforms: Windows, FreeBSD, Linux, macOS)

* bpo-36035: Added fix for broken symlinks in combination with pathlib

* bpo-35983: Added new trashcan macros to deal with a double
  deallocation that could occur when the "tp_dealloc" of a subclass
  calls the "tp_dealloc" of a base class and that base class uses the
  trashcan mechanism. Patch by Jeroen Demeyer.

* bpo-20602: Do not clear "sys.flags" and "sys.float_info" during
  shutdown. Patch by Zackery Spytz.

* bpo-26826: Expose "copy_file_range()" as a low level API in the "os"
  module.

* bpo-32388: Remove cross-version binary compatibility requirement in
  tp_flags.

* bpo-31862: Port binascii to PEP 489 multiphase initialization. Patch
  by Marcel Plch.


Library
-------

* bpo-37128: Added "math.perm()".

* bpo-37120: Add SSLContext.num_tickets to control the number of
  TLSv1.3 session tickets.

* bpo-12202: Fix the error handling in
  "msilib.SummaryInformation.GetProperty()". Patch by Zackery Spytz.

* bpo-26835: The fcntl module now contains file sealing constants for
  sealing of memfds.

* bpo-29262: Add "get_origin()" and "get_args()" introspection helpers
  to "typing" module.

* bpo-12639: "msilib.Directory.start_component()" no longer fails if
  *keyfile* is not "None".

* bpo-36999: Add the "asyncio.Task.get_coro()" method to publicly
  expose the tasks’s coroutine object.

* bpo-35246: Make "asyncio.create_subprocess_exec()" accept path-like
  arguments.

* bpo-35279: Change default *max_workers* of "ThreadPoolExecutor" from
  "cpu_count() * 5" to "min(32, cpu_count() + 4)".  Previous value was
  unreasonably large on many cores machines.

* bpo-37076: "_thread.start_new_thread()" now logs uncaught exception
  raised by the function using "sys.unraisablehook()", rather than
  "sys.excepthook()", so the hook gets access to the function which
  raised the exception.

* bpo-33725: On macOS, the "multiprocessing" module now uses *spawn*
  start method by default.

* bpo-37054: Fix destructor "_pyio.BytesIO" and "_pyio.TextIOWrapper":
  initialize their "_buffer" attribute as soon as possible (in the
  class body), because it’s used by "__del__()" which calls "close()".

* bpo-37058: PEP 544: Add "Protocol" and "@runtime_checkable" to the
  "typing" module.

* bpo-36933: The functions "sys.set_coroutine_wrapper" and
  "sys.get_coroutine_wrapper" that were deprecated and marked for
  removal in 3.8 have been removed.

* bpo-37047: Handle late binding and attribute access in
  "unittest.mock.AsyncMock" setup for autospeccing. Document newly
  implemented async methods in "unittest.mock.MagicMock".

* bpo-37049: PEP 589: Add "TypedDict" to the "typing" module.

* bpo-37046: PEP 586: Add "Literal" to the "typing" module.

* bpo-37045: PEP 591: Add "Final" qualifier and "@final" decorator to
  the "typing" module.

* bpo-37035: Don’t log OSError based exceptions if a fatal error has
  occurred in asyncio transport. Peer can generate almost any OSError,
  user cannot avoid these exceptions by fixing own code. Errors are
  still propagated to user code, it’s just logging them is pointless
  and pollute asyncio logs.

* bpo-37001: "symtable.symtable()" now accepts the same input types
  for source code as the built-in "compile()" function. Patch by Dino
  Viehland.

* bpo-37028: Implement asyncio REPL

* bpo-37027: Return safe to use proxy socket object from
  transport.get_extra_info(‘socket’)

* bpo-32528: Make asyncio.CancelledError a BaseException.

  This will address the common mistake many asyncio users make: an
  “except Exception” clause breaking Tasks cancellation.

  In addition to this change, we stop inheriting asyncio.TimeoutError
  and asyncio.InvalidStateError from their concurrent.futures.*
  counterparts. There’s no point for these exceptions to share the
  inheritance chain.

* bpo-1230540: Add a new "threading.excepthook()" function which
  handles uncaught "threading.Thread.run()" exception. It can be
  overridden to control how uncaught "threading.Thread.run()"
  exceptions are handled.

* bpo-36996: Handle "unittest.mock.patch()" used as a decorator on
  async functions.

* bpo-37008: Add support for calling "next()" with the mock resulting
  from "unittest.mock.mock_open()"

* bpo-27737: Allow whitespace only header encoding in "email.header" -
  by Batuhan Taskaya

* bpo-36969: PDB command "args" now  display positional only
  arguments. Patch contributed by Rémi Lapeyre.

* bpo-36969: PDB command "args" now  display keyword only arguments.
  Patch contributed by Rémi Lapeyre.

* bpo-36983: Add missing names to "typing.__all__": "ChainMap",
  "ForwardRef", "OrderedDict" - by Anthony Sottile.

* bpo-36972: Add SupportsIndex protocol to the typing module to allow
  type checking to detect classes that can be passed to "hex()",
  "oct()" and "bin()".

* bpo-32972: Implement "unittest.IsolatedAsyncioTestCase" to help
  testing asyncio-based code.

* bpo-36952: "fileinput.input()" and "fileinput.FileInput" **bufsize**
  argument has been removed (was deprecated and ignored since Python
  3.6), and as a result the **mode** and **openhook** arguments have
  been made keyword-only.

* bpo-36952: Starting with Python 3.3, importing ABCs from
  "collections" is deprecated, and import should be done from
  "collections.abc". Still being able to import from "collections" was
  marked for removal in 3.8, but has been delayed to 3.9;
  documentation and "DeprecationWarning" clarified.

* bpo-36949: Implement __repr__ for WeakSet objects.

* bpo-36948: Fix "NameError" in "urllib.request.URLopener.retrieve()".
  Patch by Karthikeyan Singaravelan.

* bpo-33524: Fix the folding of email header when the max_line_length
  is 0 or None and the header contains non-ascii characters.
  Contributed by Licht Takeuchi (@Licht-T).

* bpo-24564: "shutil.copystat()" now ignores "errno.EINVAL" on
  "os.setxattr()" which may occur when copying files on filesystems
  without extended attributes support.

  Original patch by Giampaolo Rodola, updated by Ying Wang.

* bpo-36888: Python child processes can now access the status of their
  parent process using multiprocessing.process.parent_process

* bpo-36921: Deprecate "@coroutine" for sake of "async def".

* bpo-25652: Fix bug in "__rmod__" of "UserString" - by Batuhan
  Taskaya.

* bpo-36916: Remove a message about an unhandled exception in a task
  when writer.write() is used without await and writer.drain() fails
  with an exception.

* bpo-36889: Introduce "asyncio.Stream" class that merges
  "asyncio.StreamReader" and "asyncio.StreamWriter" functionality.
  "asyncio.Stream" can work in readonly, writeonly and readwrite
  modes. Provide "asyncio.connect()", "asyncio.connect_unix()",
  "asyncio.connect_read_pipe()" and "asyncio.connect_write_pipe()"
  factories to open "asyncio.Stream" connections. Provide
  "asyncio.StreamServer" and "UnixStreamServer" to serve servers with
  asyncio.Stream API. Modify "asyncio.create_subprocess_shell()" and
  "asyncio.create_subprocess_exec()" to use "asyncio.Stream" instead
  of deprecated "StreamReader" and "StreamWriter". Deprecate
  "asyncio.StreamReader" and "asyncio.StreamWriter". Deprecate usage
  of private classes, e.g. "asyncio.FlowControlMixing" and
  "asyncio.StreamReaderProtocol" outside of asyncio package.

* bpo-36845: Added validation of integer prefixes to the construction
  of IP networks and interfaces in the ipaddress module.

* bpo-23378: Add an extend action to argparser.

* bpo-36867: Fix a bug making a SharedMemoryManager instance and its
  parent process use two separate resource_tracker processes.

* bpo-23896: Adds a grammar to lib2to3.pygram that contains exec as a
  function not as statement.

* bpo-36895: The function "time.clock()" was deprecated in 3.3 in
  favor of "time.perf_counter()" and marked for removal in 3.8, it has
  removed.

* bpo-35545: Fix asyncio discarding IPv6 scopes when ensuring hostname
  resolutions internally

* bpo-36887: Add new function "math.isqrt()" to compute integer square
  roots.

* bpo-34632: Introduce the "importlib.metadata" module with
  (provisional) support for reading metadata from third-party
  packages.

* bpo-36878: When using "type_comments=True" in "ast.parse", treat "#
  type: ignore" followed by a non-alphanumeric character and then
  arbitrary text as a type ignore, instead of requiring nothing but
  whitespace or another comment. This is to permit formations such as
  "# type: ignore[E1000]".

* bpo-36778: "cp65001" encoding (Windows code page 65001) becomes an
  alias to "utf_8" encoding.

* bpo-36867: The multiprocessing.resource_tracker replaces the
  multiprocessing.semaphore_tracker module. Other than semaphores,
  resource_tracker also tracks shared_memory segments.

* bpo-30262: The "Cache" and "Statement" objects of the "sqlite3"
  module are not exposed to the user.  Patch by Aviv Palivoda.

* bpo-24538: In "shutil.copystat()", first copy extended file
  attributes and then file permissions, since extended attributes can
  only be set on the destination while it is still writeable.

* bpo-36829: Add new "sys.unraisablehook()" function which can be
  overridden to control how “unraisable exceptions” are handled. It is
  called when an exception has occurred but there is no way for Python
  to handle it. For example, when a destructor raises an exception or
  during garbage collection ("gc.collect()").

* bpo-36832: Introducing "zipfile.Path", a pathlib-compatible wrapper
  for traversing zip files.

* bpo-36814: Fix an issue where os.posix_spawnp() would incorrectly
  raise a TypeError when file_actions is None.

* bpo-33110: Handle exceptions raised by functions added by
  concurrent.futures add_done_callback correctly when the Future has
  already completed.

* bpo-26903: Limit "max_workers" in "ProcessPoolExecutor" to 61 to
  work around a WaitForMultipleObjects limitation.

* bpo-36813: Fix "QueueListener" to call "queue.task_done()" upon
  stopping. Patch by Bar Harel.

* bpo-36806: Forbid creation of asyncio stream objects like
  StreamReader, StreamWriter, Process, and their protocols outside of
  asyncio package.

* bpo-36802: Provide both sync and async calls for
  StreamWriter.write() and StreamWriter.close()

* bpo-36801: Properly handle SSL connection closing in asyncio
  StreamWriter.drain() call.

* bpo-36785: Implement PEP 574 (pickle protocol 5 with out-of-band
  buffers).

* bpo-36772: functools.lru_cache() can now be used as a straight
  decorator in addition to its existing usage as a function that
  returns a decorator.

* bpo-6584: Add a "BadGzipFile" exception to the "gzip" module.

* bpo-36748: Optimized write buffering in C implementation of
  "TextIOWrapper". Writing ASCII string to "TextIOWrapper" with ascii,
  latin1, or utf-8 encoding is about 20% faster.  Patch by Inada
  Naoki.

* bpo-8138: Don’t mark "wsgiref.simple_server.SimpleServer" as multi-
  threaded since "wsgiref.simple_server.WSGIServer" is single-
  threaded.

* bpo-22640: "py_compile.compile()" now supports silent mode. Patch by
  Joannah Nanjekye

* bpo-29183: Fix double exceptions in "wsgiref.handlers.BaseHandler"
  by calling its "close()" method only when no exception is raised.

* bpo-36548: Improved the repr of regular expression flags.

* bpo-36542: The signature of Python functions can now be overridden
  by specifying the "__text_signature__" attribute.

* bpo-36533: Reinitialize logging.Handler locks in forked child
  processes instead of attempting to acquire them all in the parent
  before forking only to be released in the child process.  The
  acquire/release pattern was leading to deadlocks in code that has
  implemented any form of chained logging handlers that depend upon
  one another as the lock acquisition order cannot be guaranteed.

* bpo-35252: Throw a TypeError instead of an AssertionError when using
  an invalid type annotation with singledispatch.

* bpo-35900: Allow reduction methods to return a 6-item tuple where
  the 6th item specifies a custom state-setting method that’s called
  instead of the regular "__setstate__" method.

* bpo-35900: enable custom reduction callback registration for
  functions and classes in _pickle.c, using the new Pickler’s
  attribute "reducer_override"

* bpo-36368: Fix a bug crashing SharedMemoryManager instances in
  interactive sessions after a ctrl-c (KeyboardInterrupt) was sent

* bpo-31904: Fix mmap fail for VxWorks

* bpo-27497: "csv.DictWriter.writeheader()" now returns the return
  value of the underlying "csv.Writer.writerow()" method. Patch
  contributed by Ashish Nitin Patil.

* bpo-36239: Parsing .mo files now ignores comments starting and
  ending with #-#-#-#-#.

* bpo-26707: Enable plistlib to read and write binary plist files that
  were created as a KeyedArchive file. Specifically, this allows the
  plistlib to process 0x80 tokens as UID objects.

* bpo-31904: Add posix module support for VxWorks.

* bpo-35125: Asyncio: Remove inner callback on outer cancellation in
  shield

* bpo-35721: Fix "asyncio.SelectorEventLoop.subprocess_exec()" leaks
  file descriptors if "Popen" fails and called with
  "stdin=subprocess.PIPE". Patch by Niklas Fiekas.

* bpo-31855: "unittest.mock.mock_open()" results now respects the
  argument of read([size]). Patch contributed by Rémi Lapeyre.

* bpo-35431: Implement "math.comb()" that returns binomial
  coefficient, that computes the number of ways to choose k items from
  n items without repetition and without order. Patch by Yash Aggarwal
  and Keller Fuchs.

* bpo-26660: Fixed permission errors in "TemporaryDirectory" clean up.
  Previously "TemporaryDirectory.cleanup()" failed when non-writeable
  or non-searchable files or directories were created inside a
  temporary directory.

* bpo-34271: Add debugging helpers to ssl module. It’s now possible to
  dump key material and to trace TLS protocol. The default and stdlib
  contexts also support SSLKEYLOGFILE env var.

* bpo-26467: Added AsyncMock to support using unittest to mock asyncio
  coroutines. Patch by Lisa Roach.

* bpo-33569: dataclasses.InitVar: Exposes the type used to create the
  init var.

* bpo-34424: Fix serialization of messages containing encoded strings
  when the policy.linesep is set to a multi-character string. Patch by
  Jens Troeger.

* bpo-34303: Performance of "functools.reduce()" is slightly improved.
  Patch by Sergey Fedoseev.

* bpo-33361: Fix a bug in "codecs.StreamRecoder" where seeking might
  leave old data in a buffer and break subsequent read calls. Patch by
  Ammar Askar.

* bpo-22454: The "shlex" module now exposes "shlex.join()", the
  inverse of "shlex.split()". Patch by Bo Bayles.

* bpo-31922: "asyncio.AbstractEventLoop.create_datagram_endpoint()":
  Do not connect UDP socket when broadcast is allowed. This allows to
  receive replies after a UDP broadcast.

* bpo-24882: Change ThreadPoolExecutor to use existing idle threads
  before spinning up new ones.

* bpo-31961: Added support for bytes and path-like objects in
  "subprocess.Popen()" on Windows.  The *args* parameter now accepts a
  *path-like object* if *shell* is "False" and a sequence containing
  bytes and path-like objects. The *executable* parameter now accepts
  a bytes and *path-like object*. The *cwd* parameter now accepts a
  bytes object. Based on patch by Anders Lorentsen.

* bpo-33123: "pathlib.Path.unlink" now accepts a *missing_ok*
  parameter to avoid a "FileNotFoundError" from being raised. Patch by
  Robert Buchholz.

* bpo-32941: Allow "mmap.mmap" objects to access the madvise() system
  call (through "mmap.mmap.madvise()").

* bpo-22102: Added support for ZIP files with disks set to 0. Such
  files are commonly created by builtin tools on Windows when use
  ZIP64 extension. Patch by Francisco Facioni.

* bpo-32515: trace.py can now run modules via python3 -m trace -t
  –module module_name

* bpo-32299: Changed "unittest.mock.patch.dict()" to return the
  patched dictionary when used as context manager. Patch by Vadim
  Tsander.

* bpo-27141: Added a "__copy__()" to "collections.UserList" and
  "collections.UserDict" in order to correctly implement shallow
  copying of the objects. Patch by Bar Harel.

* bpo-31829: "\r", "\0" and "\x1a" (end-of-file on Windows) are now
  escaped in protocol 0 pickles of Unicode strings. This allows to
  load them without loss from files open in text mode in Python 2.

* bpo-23395: "_thread.interrupt_main()" now avoids setting the Python
  error status if the "SIGINT" signal is ignored or not handled by
  Python.


Documentation
-------------

* bpo-36896: Clarify that some types have unstable constructor
  signature between Python versions.

* bpo-36686: Improve documentation of the stdin, stdout, and stderr
  arguments of the "asyncio.subprocess_exec" function to specify which
  values are supported. Also mention that decoding as text is not
  supported.

  Add a few tests to verify that the various values passed to the std*
  arguments actually work.

* bpo-36984: Improve version added references in "typing" module - by
  Anthony Sottile.

* bpo-36868: What’s new now mentions
  SSLContext.hostname_checks_common_name instead of
  SSLContext.host_flags.

* bpo-35924: Add a note to the "curses.addstr()" documentation to warn
  that multiline strings can cause segfaults because of an ncurses
  bug.

* bpo-36783: Added C API Documentation for Time_FromTimeAndFold and
  PyDateTime_FromDateAndTimeAndFold as per PEP 495. Patch by Edison
  Abahurire.

* bpo-36797: More of the legacy distutils documentation has been
  either pruned, or else more clearly marked as being retained solely
  until the setuptools documentation covers it independently.

* bpo-22865: Add detail to the documentation on the "pty.spawn"
  function.

* bpo-35397: Remove deprecation and document urllib.parse.unwrap().
  Patch contributed by Rémi Lapeyre.

* bpo-32995: Added the context variable in glossary.

* bpo-33519: Clarify that "copy()" is not part of the
  "MutableSequence" ABC.

* bpo-33482: Make "codecs.StreamRecoder.writelines" take a list of
  bytes.

* bpo-25735: Added documentation for func factorial to indicate that
  returns integer values

* bpo-20285: Expand object.__doc__ (docstring) to make it clearer.
  Modify pydoc.py so that help(object) lists object methods (for other
  classes, help omits methods of the object base class.)


Tests
-----

* bpo-37069: Modify test_coroutines, test_cprofile, test_generators,
  test_raise, test_ssl and test_yield_from to use
  "test.support.catch_unraisable_exception()" rather than
  "test.support.captured_stderr()".

* bpo-37098: Fix test_memfd_create on older Linux Kernels.

* bpo-37081: Test with OpenSSL 1.1.1c

* bpo-36829: Add "test.support.catch_unraisable_exception()": context
  manager catching unraisable exception using "sys.unraisablehook()".

* bpo-36915: The main regrtest process now always removes all
  temporary directories of worker processes even if they crash or if
  they are killed on KeyboardInterrupt (CTRL+c).

* bpo-36719: “python3 -m test -jN …” now continues the execution of
  next tests when a worker process crash (CHILD_ERROR state).
  Previously, the test suite stopped immediately. Use –failfast to
  stop at the first error.

* bpo-36816: Update Lib/test/selfsigned_pythontestdotnet.pem to match
  self-signed.pythontest.net’s new TLS certificate.

* bpo-35925: Skip httplib and nntplib networking tests when they would
  otherwise fail due to a modern OS or distro with a default OpenSSL
  policy of rejecting connections to servers with weak certificates.

* bpo-36782: Add tests for several C API functions in the "datetime"
  module. Patch by Edison Abahurire.

* bpo-36342: Fix test_multiprocessing in test_venv if platform lacks
  functioning sem_open.


Build
-----

* bpo-36721: To embed Python into an application, a new "--embed"
  option must be passed to "python3-config --libs --embed" to get
  "-lpython3.8" (link the application to libpython). To support both
  3.8 and older, try "python3-config --libs --embed" first and
  fallback to "python3-config --libs" (without "--embed") if the
  previous command fails.

  Add a pkg-config "python-3.8-embed" module to embed Python into an
  application: "pkg-config python-3.8-embed --libs" includes
  "-lpython3.8". To support both 3.8 and older, try "pkg-config
  python-X.Y-embed --libs" first and fallback to "pkg-config
  python-X.Y --libs" (without "--embed") if the previous command fails
  (replace "X.Y" with the Python version).

  On the other hand, "pkg-config python3.8 --libs" no longer contains
  "-lpython3.8". C extensions must not be linked to libpython (except
  on Android, case handled by the script); this change is backward
  incompatible on purpose.

* bpo-36786: “make install” now runs compileall in parallel.


Windows
-------

* bpo-36965: include of STATUS_CONTROL_C_EXIT without depending on MSC
  compiler

* bpo-35926: Update to OpenSSL 1.1.1b for Windows.

* bpo-29883: Add Windows support for UDP transports for the Proactor
  Event Loop. Patch by Adam Meily.

* bpo-33407: The "Py_DEPRECATED()" macro has been implemented for
  MSVC.


macOS
-----

* bpo-36231: Support building Python on macOS without /usr/include
  installed. As of macOS 10.14, system header files are only available
  within an SDK provided by either the Command Line Tools or the Xcode
  app.


IDLE
----

* bpo-35610: Replace now redundant .context_use_ps1 with
  .prompt_last_line. This finishes change started in bpo-31858.

* bpo-37038: Make idlelib.run runnable; add test clause.

* bpo-36958: Print any argument other than None or int passed to
  SystemExit or sys.exit().

* bpo-36807: When saving a file, call os.fsync() so bits are flushed
  to e.g. USB drive.

* bpo-32411: In browser.py, remove extraneous sorting by line number
  since dictionary was created in line number order.


Tools/Demos
-----------

* bpo-37053: Handle strings like u”bar” correctly in
  Tools/parser/unparse.py. Patch by Chih-Hsuan Yen.


C API
-----

* bpo-36763: Implement the **PEP 587** “Python Initialization
  Configuration”.

* bpo-36379: Fix crashes when attempting to use the *modulo* parameter
  when "__ipow__" is implemented in C.

* bpo-37107: Update "PyObject_CallMethodObjArgs()" and
  "_PyObject_CallMethodIdObjArgs" to use "_PyObject_GetMethod" to
  avoid creating a bound method object in many cases. Patch by Michael
  J. Sullivan.

* bpo-36974: Implement **PEP 590**: Vectorcall: a fast calling
  protocol for CPython. This is a new protocol to optimize calls of
  custom callable objects.

* bpo-36763: "Py_Main()" now returns the exitcode rather than calling
  "Py_Exit(exitcode)" when calling "PyErr_Print()" if the current
  exception type is "SystemExit".

* bpo-36922: Add new type flag "Py_TPFLAGS_METHOD_DESCRIPTOR" for
  objects behaving like unbound methods. These are objects supporting
  the optimization given by the "LOAD_METHOD"/"CALL_METHOD" opcodes.
  See PEP 590.

* bpo-36728: The "PyEval_ReInitThreads()" function has been removed
  from the C API. It should not be called explicitly: use
  "PyOS_AfterFork_Child()" instead.


Python 3.8.0 alpha 4
====================

*Release date: 2019-05-06*


Security
--------

* bpo-36742: Fixes mishandling of pre-normalization characters in
  urlsplit().

* bpo-30458: Address CVE-2019-9740 by disallowing URL paths with
  embedded whitespace or control characters through into the
  underlying http client request.  Such potentially malicious header
  injection URLs now cause an http.client.InvalidURL exception to be
  raised.

* bpo-35755: "shutil.which()" now uses "os.confstr("CS_PATH")" if
  available and if the "PATH" environment variable is not set. Remove
  also the current directory from "posixpath.defpath". On Unix,
  "shutil.which()" and the "subprocess" module no longer search the
  executable in the current directory if the "PATH" environment
  variable is not set.


Core and Builtins
-----------------

* bpo-36722: In debug build, import now also looks for C extensions
  compiled in release mode and for C extensions compiled in the stable
  ABI.

* bpo-32849: Fix Python Initialization code on FreeBSD to detect
  properly when stdin file descriptor (fd 0) is invalid.

* bpo-36623: Remove parser headers and related function declarations
  that lack implementations after the removal of pgen.

* bpo-20180: "dict.pop()" is now up to 33% faster thanks to Argument
  Clinic. Patch by Inada Naoki.

* bpo-36611: Debug memory allocators: disable serialno field by
  default from debug hooks on Python memory allocators to reduce the
  memory footprint by 5%. Enable "tracemalloc" to get the traceback
  where a memory block has been allocated when a fatal memory error is
  logged to decide where to put a breakpoint. Compile Python with
  "PYMEM_DEBUG_SERIALNO" defined to get back the field.

* bpo-36588: On AIX, "sys.platform" doesn’t contain the major version
  anymore. Always return "'aix'", instead of "'aix3'" .. "'aix7'".
  Since older Python versions include the version number, it is
  recommended to always use "sys.platform.startswith('aix')".
  Contributed by M. Felt.

* bpo-36549: Change str.capitalize to use titlecase for the first
  character instead of uppercase.

* bpo-36540: Implement **PEP 570** (Python positional-only
  parameters). Patch by Pablo Galindo.

* bpo-36475: "PyEval_AcquireLock()" and "PyEval_AcquireThread()" now
  terminate the current thread if called while the interpreter is
  finalizing, making them consistent with "PyEval_RestoreThread()",
  "Py_END_ALLOW_THREADS()", and "PyGILState_Ensure()".

* bpo-36504: Fix signed integer overflow in _ctypes.c’s
  "PyCArrayType_new()".

* bpo-20844: Fix running script with encoding cookie and LF line
  ending may fail on Windows.

* bpo-24214: Fixed support of the surrogatepass error handler in the
  UTF-8 incremental decoder.

* bpo-36452: Changing "dict" keys during iteration of the dict itself,
  "keys()", "values()", or "items()" will now be detected in certain
  corner cases where keys are deleted/added so that the number of keys
  isn’t changed. A "RuntimeError" will be raised after "len(dict)"
  iterations. Contributed by Thomas Perl.

* bpo-36459: Fix a possible double "PyMem_FREE()" due to tokenizer.c’s
  "tok_nextc()".

* bpo-36433: Fixed TypeError message in classmethoddescr_call.

* bpo-36430: Fix a possible reference leak in "itertools.count()".

* bpo-36440: Include node names in "ParserError" messages, instead of
  numeric IDs. Patch by A. Skrobov.

* bpo-36143: Regenerate "keyword" from the Grammar and Tokens file
  using pgen. Patch by Pablo Galindo.

* bpo-18372: Add missing "PyObject_GC_Track()" calls in the "pickle"
  module. Patch by Zackery Spytz.


Library
-------

* bpo-35952: Fix pythoninfo when the compiler is missing.

* bpo-28238: The ".find*()" methods of xml.etree.ElementTree can now
  search for wildcards like "{*}tag" and "{ns}*" that match a tag in
  any namespace or all tags in a namespace.  Patch by Stefan Behnel.

* bpo-26978: "pathlib.path.link_to()" is now implemented. It creates a
  hard link pointing to a path.

* bpo-1613500: "fileinput.FileInput" now uses the input file mode to
  correctly set the output file mode (previously it was hardcoded to
  "'w'")  when "inplace=True" is passed to its constructor.

* bpo-36734: Fix compilation of "faulthandler.c" on HP-UX. Initialize
  "stack_t current_stack" to zero using "memset()".

* bpo-13611: The xml.etree.ElementTree packages gained support for
  C14N 2.0 serialisation. Patch by Stefan Behnel.

* bpo-36669: Add missing matrix multiplication operator support to
  weakref.proxy.

* bpo-36676: The XMLParser() in xml.etree.ElementTree provides
  namespace prefix context to the parser target if it defines the
  callback methods “start_ns()” and/or “end_ns()”. Patch by Stefan
  Behnel.

* bpo-36673: The TreeBuilder and XMLPullParser in
  xml.etree.ElementTree gained support for parsing comments and
  processing instructions. Patch by Stefan Behnel.

* bpo-36650: The C version of functools.lru_cache() was treating calls
  with an empty "**kwargs" dictionary as being distinct from calls
  with no keywords at all. This did not result in an incorrect answer,
  but it did trigger an unexpected cache miss.

* bpo-28552: Fix "distutils.sysconfig" if "sys.executable" is "None"
  or an empty string: use "os.getcwd()" to initialize "project_base".
  Fix also the distutils build command: don’t use "sys.executable" if
  it is "None" or an empty string.

* bpo-35755: "shutil.which()" and "distutils.spawn.find_executable()"
  now use "os.confstr("CS_PATH")" if available instead of
  "os.defpath", if the "PATH" environment variable is not set.
  Moreover, don’t use "os.confstr("CS_PATH")" nor "os.defpath" if the
  "PATH" environment variable is set to an empty string.

* bpo-25430: improve performance of "IPNetwork.__contains__()"

* bpo-30485: Path expressions in xml.etree.ElementTree can now avoid
  explicit namespace prefixes for tags (or the “{namespace}tag”
  notation) by passing a default namespace with an empty string
  prefix.

* bpo-36613: Fix "asyncio" wait() not removing callback if exception

* bpo-36598: Fix "isinstance" check for Mock objects with spec when
  the code is executed under tracing. Patch by Karthikeyan
  Singaravelan.

* bpo-18748: In development mode ("-X" "dev") and in debug build, the
  "io.IOBase" destructor now logs "close()" exceptions. These
  exceptions are silent by default in release mode.

* bpo-36575: The "_lsprof" module now uses internal timer same to
  "time.perf_counter()" by default. "gettimeofday(2)" was used on
  Unix. New timer has better resolution on most Unix platforms and
  timings are no longer impacted by system clock updates since
  "perf_counter()" is monotonic. Patch by Inada Naoki.

* bpo-33461: "json.loads" now emits "DeprecationWarning" when
  "encoding" option is specified.  Patch by Matthias Bussonnier.

* bpo-36559: The random module now prefers the lean internal _sha512
  module over hashlib for seed(version=2) to optimize import time.

* bpo-17561: Set backlog=None as the default for socket.create_server.

* bpo-34373: Fix "time.mktime()" error handling on AIX for year before
  1970.

* bpo-36232: Improve error message when trying to open existing DBM
  database that actually doesn’t exist. Patch by Marco Rougeth.

* bpo-36546: Add statistics.quantiles()

* bpo-36050: Optimized "http.client.HTTPResponse.read()" for large
  response. Patch by Inada Naoki.

* bpo-36522: If *debuglevel* is set to >0 in "http.client", print all
  values for headers with multiple values for the same header name.
  Patch by Matt Houglum.

* bpo-36492: Deprecated passing required arguments like *func* as
  keyword arguments in functions which should accept arbitrary keyword
  arguments and pass them to other function. Arbitrary keyword
  arguments (even with names “self” and “func”) can now be passed to
  these functions if the required arguments are passed as positional
  arguments.

* bpo-27181: Add statistics.geometric_mean().

* bpo-30427: "os.path.normcase()" relies on "os.fspath()" to check the
  type of its argument. Redundant checks have been removed from its
  "posixpath.normcase()" and "ntpath.normcase()" implementations.
  Patch by Wolfgang Maier.

* bpo-36385: Stop rejecting IPv4 octets for being ambiguously octal.
  Leading zeros are ignored, and no longer are assumed to specify
  octal octets. Octets are always decimal numbers. Octets must still
  be no more than three digits, including leading zeroes.

* bpo-36434: Errors during writing to a ZIP file no longer prevent to
  properly close it.

* bpo-36407: Fixed wrong indentation writing for CDATA section in
  xml.dom.minidom. Patch by Vladimir Surjaninov.

* bpo-36326: inspect.getdoc() can now find docstrings for member
  objects when __slots__ is a dictionary.

* bpo-36366: Calling "stop()" on an unstarted or stopped
  "unittest.mock.patch()" object will now return "None" instead of
  raising "RuntimeError", making the method idempotent. Patch by
  Karthikeyan Singaravelan.

* bpo-36348: The "imap.IMAP4.logout()" method no longer ignores
  silently arbitrary exceptions.

* bpo-31904: Add time module support and fix test_time faiures for
  VxWorks.

* bpo-36227: Added support for keyword arguments "default_namespace"
  and "xml_declaration" in functions ElementTree.tostring() and
  ElementTree.tostringlist().

* bpo-36004: Added new alternate constructors
  "datetime.date.fromisocalendar()" and
  "datetime.datetime.fromisocalendar()", which construct date objects
  from ISO year, week number and weekday; these are the inverse of
  each class’s "isocalendar" method. Patch by Paul Ganssle.

* bpo-35936: "modulefinder" no longer depends on the deprecated "imp"
  module, and the initializer for "modulefinder.ModuleFinder" now has
  immutable default arguments. Patch by Brandt Bucher.

* bpo-35376: "modulefinder" correctly handles modules that have the
  same name as a bad package. Patch by Brandt Bucher.

* bpo-17396: "modulefinder" no longer crashes when encountering syntax
  errors in followed imports. Patch by Brandt Bucher.

* bpo-35934: Added "create_server()" and "has_dualstack_ipv6()"
  convenience functions to automate the necessary tasks usually
  involved when creating a server socket, including accepting both
  IPv4 and IPv6 connections on the same socket.  (Contributed by
  Giampaolo Rodola in bpo-17561.)

* bpo-23078: Add support for "classmethod()" and "staticmethod()" to
  "unittest.mock.create_autospec()".  Initial patch by Felipe Ochoa.

* bpo-35416: Fix potential resource warnings in distutils. Patch by
  Mickaël Schoentgen.

* bpo-25451: Add transparency methods to "tkinter.PhotoImage".  Patch
  by Zackery Spytz.

* bpo-35082: Don’t return deleted attributes when calling dir on a
  "unittest.mock.Mock".

* bpo-34547: "wsgiref.handlers.BaseHandler" now handles abrupt client
  connection terminations gracefully. Patch by Petter Strandmark.

* bpo-31658: "xml.sax.parse()" now supports *path-like*. Patch by
  Mickaël Schoentgen.

* bpo-34139: Remove stale unix datagram socket before binding

* bpo-33530: Implemented Happy Eyeballs in
  "asyncio.create_connection()". Added two new arguments,
  *happy_eyeballs_delay* and *interleave*, to specify Happy Eyeballs
  behavior.

* bpo-33291: Do not raise AttributeError when calling the inspect
  functions isgeneratorfunction, iscoroutinefunction,
  isasyncgenfunction on a method created from an arbitrary callable.
  Instead, return False.

* bpo-31310: Fix the multiprocessing.semaphore_tracker so it is reused
  by child processes

* bpo-31292: Fix "setup.py check --restructuredtext" for files
  containing "include" directives.


Documentation
-------------

* bpo-36625: Remove obsolete comments from docstrings in
  fractions.Fraction

* bpo-30840: Document relative imports

* bpo-36523: Add docstring for io.IOBase.writelines().

* bpo-36425: New documentation translation: Simplified Chinese.

* bpo-36345: Avoid the duplication of code from
  "Tools/scripts/serve.py" in using the "literalinclude" directive for
  the basic wsgiref-based web server in the documentation of
  "wsgiref". Contributed by Stéphane Wirtel.

* bpo-36345: Using the code of the "Tools/scripts/serve.py" script as
  an example in the "wsgiref" documentation.  Contributed by Stéphane
  Wirtel.

* bpo-36157: Added Documention for  PyInterpreterState_Main().

* bpo-33043: Updates the docs.python.org page with the addition of a
  ‘Contributing to Docs’ link at the end of the page (between
  ‘Reporting Bugs’ and ‘About Documentation’). Updates the ‘Found a
  Bug’ page with additional links and information in the Documentation
  Bugs section.

* bpo-35581: @typing.type_check_only now allows type stubs to mark
  functions and classes not available during runtime.

* bpo-33832: Add glossary entry for ‘magic method’.

* bpo-32913: Added re.Match.groupdict example to regex HOWTO.


Tests
-----

* bpo-36719: regrtest now always detects uncollectable objects.
  Previously, the check was only enabled by "--findleaks". The check
  now also works with "-jN/--multiprocess N". "--findleaks" becomes a
  deprecated alias to "--fail-env-changed".

* bpo-36725: When using multiprocessing mode (-jN), regrtest now
  better reports errors if a worker process fails, and it exits
  immediately on a worker thread failure or when interrupted.

* bpo-36454: Change test_time.test_monotonic() to test only the lower
  bound of elapsed time after a sleep command rather than the upper
  bound. This prevents unnecessary test failures on slow buildbots.
  Patch by Victor Stinner.

* bpo-32424: Improve test coverage for xml.etree.ElementTree. Patch by
  Gordon P. Hemsley.

* bpo-32424: Fix typo in test_cyclic_gc() test for
  xml.etree.ElementTree. Patch by Gordon P. Hemsley.

* bpo-36635: Add a new "_testinternalcapi" module to test the internal
  C API.

* bpo-36629: Fix "test_imap4_host_default_value()" of "test_imaplib":
  catch also "errno.ENETUNREACH" error.

* bpo-36611: Fix "test_sys.test_getallocatedblocks()" when
  "tracemalloc" is enabled.

* bpo-36560: Fix reference leak hunting in regrtest: compute also
  deltas (of reference count, allocated memory blocks, file descriptor
  count) during warmup, to ensure that everything is initialized
  before starting to hunt reference leaks.

* bpo-36565: Fix reference hunting ("python3 -m test -R 3:3") when
  Python has no built-in abc module.

* bpo-31904: Port test_resource to VxWorks: skip tests cases setting
  RLIMIT_FSIZE and RLIMIT_CPU.

* bpo-31904: Fix test_tabnanny on VxWorks: adjust ENOENT error
  message.

* bpo-36436: Fix "_testcapi.pymem_buffer_overflow()": handle memory
  allocation failure.

* bpo-31904: Fix test_utf8_mode on VxWorks: Python always use UTF-8 on
  VxWorks.

* bpo-36341: Fix tests that may fail with PermissionError upon calling
  bind() on AF_UNIX sockets.


Build
-----

* bpo-36747: Remove the stale scriptsinstall Makefile target.

* bpo-21536: On Unix, C extensions are no longer linked to libpython
  except on Android and Cygwin.

  It is now possible for a statically linked Python to load a C
  extension built using a shared library Python.

  When Python is embedded, "libpython" must not be loaded with
  "RTLD_LOCAL", but "RTLD_GLOBAL" instead. Previously, using
  "RTLD_LOCAL", it was already not possible to load C extensions which
  were not linked to "libpython", such as C extensions of the standard
  library built by the "*shared*" section of "Modules/Setup".

  distutils, python-config and python-config.py have been modified.

* bpo-36707: "./configure --with-pymalloc" no longer adds the "m" flag
  to SOABI (sys.implementation.cache_tag). Enabling or disabling
  pymalloc has no impact on the ABI.

* bpo-36635: Change "PyAPI_FUNC(type)", "PyAPI_DATA(type)" and
  "PyMODINIT_FUNC" macros of "pyport.h" when "Py_BUILD_CORE_MODULE" is
  defined. The "Py_BUILD_CORE_MODULE" define must be now be used to
  build a C extension as a dynamic library accessing Python internals:
  export the PyInit_xxx() function in DLL exports on Windows.

* bpo-31904: Don’t build the "_crypt" extension on VxWorks.

* bpo-36618: Add "-fmax-type-align=8" to CFLAGS when clang compiler is
  detected. The pymalloc memory allocator aligns memory on 8 bytes. On
  x86-64, clang expects alignment on 16 bytes by default and so uses
  MOVAPS instruction which can lead to segmentation fault. Instruct
  clang that Python is limited to alignment on 8 bytes to use MOVUPS
  instruction instead: slower but don’t trigger a SIGSEGV if the
  memory is not aligned on 16 bytes. Sadly, the flag must be added to
  "CFLAGS" and not just "CFLAGS_NODIST", since third party C
  extensions can have the same issue.

* bpo-36605: "make tags" and "make TAGS" now also parse
  "Modules/_io/*.c" and "Modules/_io/*.h".

* bpo-36465: Release builds and debug builds are now ABI compatible:
  defining the "Py_DEBUG" macro no longer implies the "Py_TRACE_REFS"
  macro, which introduces the only ABI incompatibility. The
  "Py_TRACE_REFS" macro, which adds the "sys.getobjects()" function
  and the "PYTHONDUMPREFS" environment variable, can be set using the
  new "./configure --with-trace-refs" build option.

* bpo-36577: setup.py now correctly reports missing OpenSSL headers
  and libraries again.

* bpo-36544: Fix regression introduced in bpo-36146 refactoring
  setup.py

* bpo-36508: "python-config --ldflags" no longer includes flags of the
  "LINKFORSHARED" variable. The "LINKFORSHARED" variable must only be
  used to build executables.

* bpo-36503: Remove references to “aix3” and “aix4”. Patch by M. Felt.


Windows
-------

* bpo-35920: Added platform.win32_edition() and
  platform.win32_is_iot(). Added support for cross-compiling packages
  for Windows ARM32. Skip tests that are not expected to work on
  Windows IoT Core ARM32.

* bpo-36649: Remove trailing spaces for registry keys when installed
  via the Store.

* bpo-34144: Fixed activate.bat to correctly update codepage when
  chcp.com returns dots in output. Patch by Lorenz Mende.

* bpo-36509: Added preset-iot layout for Windows IoT ARM containers.
  This layout doesn’t contain UI components like tkinter or IDLE. It
  also doesn’t contain files to support on-target builds since Windows
  ARM32 builds must be cross-compiled when using MSVC.

* bpo-35941: enum_certificates function of the ssl module now returns
  certificates from all available certificate stores inside windows in
  a query instead of returning only certificates from the system wide
  certificate store. This includes certificates from these certificate
  stores: local machine, local machine enterprise, local machine group
  policy, current user, current user group policy, services, users.
  ssl.enum_crls() function is changed in the same way to return all
  certificate revocation lists inside the windows certificate
  revocation list stores.

* bpo-36441: Fixes creating a venv when debug binaries are installed.

* bpo-36085: Enable better DLL resolution on Windows by using safe DLL
  search paths and adding "os.add_dll_directory()".

* bpo-36010: Add the venv standard library module to the nuget
  distribution for Windows.

* bpo-29515: Add the following socket module constants on Windows:
  IPPROTO_AH IPPROTO_CBT IPPROTO_DSTOPTS IPPROTO_EGP IPPROTO_ESP
  IPPROTO_FRAGMENT IPPROTO_GGP IPPROTO_HOPOPTS IPPROTO_ICLFXBM
  IPPROTO_ICMPV6 IPPROTO_IDP IPPROTO_IGMP IPPROTO_IGP IPPROTO_IPV4
  IPPROTO_IPV6 IPPROTO_L2TP IPPROTO_MAX IPPROTO_ND IPPROTO_NONE
  IPPROTO_PGM IPPROTO_PIM IPPROTO_PUP IPPROTO_RDP IPPROTO_ROUTING
  IPPROTO_SCTP IPPROTO_ST

* bpo-35947: Added current version of libffi to cpython-source-deps.
  Change _ctypes to use current version of libffi on Windows.

* bpo-34060: Report system load when running test suite on Windows.
  Patch by Ammar Askar. Based on prior work by Jeremy Kloth.

* bpo-31512: With the Windows 10 Creators Update, non-elevated users
  can now create symlinks as long as the computer has Developer Mode
  enabled.


macOS
-----

* bpo-34602: Avoid failures setting macOS stack resource limit with
  resource.setrlimit. This reverts an earlier fix for bpo-18075 which
  forced a non-default stack size when building the interpreter
  executable on macOS.


IDLE
----

* bpo-36429: Fix starting IDLE with pyshell. Add idlelib.pyshell alias
  at top; remove pyshell alias at bottom. Remove obsolete
  __name__==’__main__’ command.


Tools/Demos
-----------

* bpo-14546: Fix the argument handling in Tools/scripts/lll.py.


C API
-----

* bpo-36763: Fix memory leak in "Py_SetStandardStreamEncoding()":
  release memory if the function is called twice.

* bpo-36641: "PyDoc_VAR(name)" and "PyDoc_STRVAR(name, str)" now
  create "static const char name[]" instead of "static char name[]".
  Patch by Inada Naoki.

* bpo-36389: Change the value of "CLEANBYTE", "DEADDYTE" and
  "FORBIDDENBYTE" internal constants used by debug hooks on Python
  memory allocators ("PyMem_SetupDebugHooks()" function). Byte
  patterns "0xCB", "0xDB" and "0xFB" have been replaced with "0xCD",
  "0xDD" and "0xFD" to use the same values than Windows CRT debug
  "malloc()" and "free()".

* bpo-36443: Since Python 3.7.0, calling "Py_DecodeLocale()" before
  "Py_Initialize()" produces mojibake if the "LC_CTYPE" locale is
  coerced and/or if the UTF-8 Mode is enabled by the user
  configuration. The LC_CTYPE coercion and UTF-8 Mode are now disabled
  by default to fix the mojibake issue. They must now be enabled
  explicitly (opt-in) using the new "_Py_PreInitialize()" API with
  "_PyPreConfig".

* bpo-36025: Fixed an accidental change to the datetime C API where
  the arguments to the "PyDate_FromTimestamp()" function were
  incorrectly interpreted as a single timestamp rather than an
  arguments tuple, which causes existing code to start raising
  "TypeError". The backwards-incompatible change was only present in
  alpha releases of Python 3.8. Patch by Paul Ganssle.

* bpo-35810: Modify "PyObject_Init" to correctly increase the refcount
  of heap- allocated Type objects. Also fix the refcounts of the heap-
  allocated types that were either doing this manually or not
  decreasing the type’s refcount in tp_dealloc


Python 3.8.0 alpha 3
====================

*Release date: 2019-03-25*


Security
--------

* bpo-36216: Changes urlsplit() to raise ValueError when the URL
  contains characters that decompose under IDNA encoding (NFKC-
  normalization) into characters that affect how the URL is parsed.

* bpo-35121: Don’t send cookies of domain A without Domain attribute
  to domain B when domain A is a suffix match of domain B while using
  a cookiejar with "http.cookiejar.DefaultCookiePolicy" policy. Patch
  by Karthikeyan Singaravelan.


Core and Builtins
-----------------

* bpo-36421: Fix a possible double decref in _ctypes.c’s
  "PyCArrayType_new()".

* bpo-36412: Fix a possible crash when creating a new dictionary.

* bpo-36398: Fix a possible crash in "structseq_repr()".

* bpo-36256: Fix bug in parsermodule when parsing a state in a DFA
  that has two or more arcs with labels of the same type. Patch by
  Pablo Galindo.

* bpo-36365: repr(structseq) is no longer limited to 512 bytes.

* bpo-36374: Fix a possible null pointer dereference in
  "merge_consts_recursive()". Patch by Zackery Spytz.

* bpo-36236: At Python initialization, the current directory is no
  longer prepended to "sys.path" if it has been removed.

* bpo-36352: Python initialization now fails with an error, rather
  than silently truncating paths, if a path is too long.

* bpo-36301: Python initialization now fails if decoding
  "pybuilddir.txt" configuration file fails at startup.

* bpo-36333: Fix leak in _PyRuntimeState_Fini. Contributed by Stéphane
  Wirtel.

* bpo-36332: The builtin "compile()" can now handle AST objects that
  contain assignment expressions. Patch by Pablo Galindo.

* bpo-36282: Improved error message for too much positional arguments
  in some builtin functions.

* bpo-30040: New empty dict uses fewer memory for now.  It used more
  memory than empty dict created by "dict.clear()".  And empty dict
  creation and deletion is about 2x faster.  Patch by Inada Naoki.

* bpo-36262: Fix an unlikely memory leak on conversion from string to
  float in the function "_Py_dg_strtod()" used by "float(str)",
  "complex(str)", "pickle.load()", "marshal.load()", etc.

* bpo-36252: Update Unicode databases to version 12.0.0.

* bpo-36218: Fix a segfault occurring when sorting a list of
  heterogeneous values. Patch contributed by Rémi Lapeyre and Elliot
  Gorokhovsky.

* bpo-36188: Cleaned up left-over vestiges of Python 2 unbound method
  handling in method objects and documentation. Patch by Martijn
  Pieters

* bpo-36124: Add a new interpreter-specific dict and expose it in the
  C-API via PyInterpreterState_GetDict().  This parallels
  PyThreadState_GetDict(). However, extension modules should continue
  using PyModule_GetState() for their own internal per-interpreter
  state.

* bpo-35975: Add a "feature_version" flag to "ast.parse()"
  (documented) and "compile()" (hidden) that allows tweaking the
  parser to support older versions of the grammar. In particular, if
  "feature_version" is 5 or 6, the hacks for the "async" and "await"
  keyword from PEP 492 are reinstated. (For 7 or higher, these are
  unconditionally treated as keywords, but they are still special
  tokens rather than "NAME" tokens that the parser driver recognizes.)

* bpo-31904: Use UTF-8 as the system encoding on VxWorks.

* bpo-36048: The "__index__()" special method will be used instead of
  "__int__()" for implicit conversion of Python numbers to C integers.
  Using the "__int__()" method in implicit conversions has been
  deprecated.

* bpo-35808: Retire pgen and use a modified version of pgen2 to
  generate the parser. Patch by Pablo Galindo.


Library
-------

* bpo-36401: The class documentation created by pydoc now has a
  separate section for readonly properties.

* bpo-36320: The typing.NamedTuple() class has deprecated the
  _field_types attribute in favor of the __annotations__ attribute
  which carried the same information. Also, both attributes were
  converted from OrderedDict to a regular dict.

* bpo-34745: Fix "asyncio" ssl memory issues caused by circular
  references

* bpo-36324: Add method to statistics.NormalDist for computing the
  inverse cumulative normal distribution.

* bpo-36321: collections.namedtuple() misspelled the name of an
  attribute. To be consistent with typing.NamedTuple, the attribute
  name should have been “_field_defaults” instead of
  “_fields_defaults”.  For backwards compatibility, both spellings are
  now created.  The misspelled version may be removed in the future.

* bpo-36297: “unicode_internal” codec is removed.  It was deprecated
  since Python 3.3. Patch by Inada Naoki.

* bpo-36298: Raise ModuleNotFoundError in pyclbr when a module can’t
  be found. Thanks to ‘mental’ for the bug report.

* bpo-36268: Switch the default format used for writing tars with
  mod:"tarfile" to the modern POSIX.1-2001 pax standard, from the
  vendor-specific GNU. Contributed by C.A.M. Gerlach.

* bpo-36285: Fix integer overflows in the array module. Patch by
  Stephan Hohe.

* bpo-31904: Add _signal module support for VxWorks.

* bpo-36272: "logging" does not silently ignore RecursionError
  anymore. Patch contributed by Rémi Lapeyre.

* bpo-36280: Add a kind field to ast.Constant. It is ‘u’ if the
  literal has a ‘u’ prefix (i.e. a Python 2 style unicode literal),
  else None.

* bpo-35931: The "pdb" "debug" command now gracefully handles all
  exceptions.

* bpo-36251: Fix format strings used for stderrprinter and re.Match
  reprs. Patch by Stephan Hohe.

* bpo-36235: Fix "CFLAGS" in "customize_compiler()" of
  "distutils.sysconfig": when the "CFLAGS" environment variable is
  defined, don’t override "CFLAGS" variable with the "OPT" variable
  anymore. Initial patch written by David Malcolm.

* bpo-35807: Update ensurepip to install pip 19.0.3 and setuptools
  40.8.0.

* bpo-36139: Release GIL when closing "mmap" objects.

* bpo-36179: Fix two unlikely reference leaks in _hashopenssl. The
  leaks only occur in out-of-memory cases.

* bpo-36169: Add overlap() method to statistics.NormalDist.  Computes
  the overlapping coefficient for two normal distributions.

* bpo-36103: Default buffer size used by "shutil.copyfileobj()" is
  changed from 16 KiB to 64 KiB on non-Windows platform to reduce
  system call overhead. Contributed by Inada Naoki.

* bpo-36130: Fix "pdb" with "skip=..." when stepping into a frame
  without a "__name__" global.  Patch by Anthony Sottile.

* bpo-35652: shutil.copytree(copy_function=…) erroneously pass
  DirEntry instead of a path string.

* bpo-35178: Ensure custom "warnings.formatwarning()" function can
  receive "line" as positional argument. Based on patch by Tashrif
  Billah.

* bpo-36106: Resolve potential name clash with libm’s sinpi(). Patch
  by Dmitrii Pasechnik.

* bpo-36091: Clean up reference to async generator in Lib/types. Patch
  by Henry Chen.

* bpo-36043: "FileCookieJar" supports *path-like object*. Contributed
  by Stéphane Wirtel

* bpo-35899: Enum has been fixed to correctly handle empty strings and
  strings with non-Latin characters (ie. ‘α’, ‘א’) without crashing.
  Original patch contributed by Maxwell. Assisted by Stéphane Wirtel.

* bpo-21269: Add "args" and "kwargs" properties to mock call objects.
  Contributed by Kumar Akshay.

* bpo-30670: "pprint.pp" has been added to pretty-print objects with
  dictionary keys being sorted with their insertion order by default.
  Parameter *sort_dicts* has been added to "pprint.pprint",
  "pprint.pformat" and "pprint.PrettyPrinter". Contributed by Rémi
  Lapeyre.

* bpo-35843: Implement "__getitem__" for "_NamespacePath".  Patch by
  Anthony Sottile.

* bpo-35802: Clean up code which checked presence of "os.stat" /
  "os.lstat" / "os.chmod" which are always present.  Patch by Anthony
  Sottile.

* bpo-35715: Librates the return value of a ProcessPoolExecutor
  _process_worker after it’s no longer needed to free memory

* bpo-35493: Use "multiprocessing.connection.wait()" instead of
  polling each 0.2 seconds for worker updates in
  "multiprocessing.Pool". Patch by Pablo Galindo.

* bpo-35661: Store the venv prompt in pyvenv.cfg.

* bpo-35121: Don’t set cookie for a request when the request path is a
  prefix match of the cookie’s path attribute but doesn’t end with
  “/”. Patch by Karthikeyan Singaravelan.

* bpo-21478: Calls to a child function created with
  "unittest.mock.create_autospec()" should propagate to the parent.
  Patch by Karthikeyan Singaravelan.

* bpo-35198: Fix C++ extension compilation on AIX


Documentation
-------------

* bpo-36329: Declare the path of the Python binary for the usage of
  "Tools/scripts/serve.py" when executing "make -C Doc/ serve".
  Contributed by Stéphane Wirtel

* bpo-36138: Improve documentation about converting datetime.timedelta
  to scalars.

* bpo-21314: A new entry was added to the Core Language Section of the
  Programming FAQ, which explaines the usage of slash(/) in the
  signature of a function. Patch by Lysandros Nikolaou


Tests
-----

* bpo-36234: test_posix.PosixUidGidTests: add tests for invalid
  uid/gid type (str). Initial patch written by David Malcolm.

* bpo-29571: Fix "test_re.test_locale_flag()":  use
  "locale.getpreferredencoding()" rather than "locale.getlocale()" to
  get the locale encoding. With some locales, "locale.getlocale()"
  returns the wrong encoding.

* bpo-36123: Fix race condition in test_socket.


Build
-----

* bpo-36356: Fix leaks that led to build failure when configured with
  address sanitizer.

* bpo-36146: Add "TEST_EXTENSIONS" constant to "setup.py" to allow to
  not build test extensions like "_testcapi".

* bpo-36146: Fix setup.py on macOS: only add "/usr/include/ffi" to
  include directories of _ctypes, not for all extensions.

* bpo-31904: Enable build system to cross-build for VxWorks RTOS.


Windows
-------

* bpo-36312: Fixed decoders for the following code pages: 50220,
  50221, 50222, 50225, 50227, 50229, 57002 through 57011, 65000 and
  42.

* bpo-36264: Don’t honor POSIX "HOME" in "os.path.expanduser" on
  windows.  Patch by Anthony Sottile.

* bpo-24643: Fix name collisions due to "#define timezone _timezone"
  in PC/pyconfig.h.


IDLE
----

* bpo-36405: Use dict unpacking in idlelib.

* bpo-36396: Remove fgBg param of idlelib.config.GetHighlight(). This
  param was only used twice and changed the return type.

* bpo-36176: Fix IDLE autocomplete & calltip popup colors. Prevent
  conflicts with Linux dark themes (and slightly darken calltip
  background).

* bpo-23205: For the grep module, add tests for findfiles, refactor
  findfiles to be a module-level function, and refactor findfiles to
  use os.walk.

* bpo-23216: Add docstrings to IDLE search modules.

* bpo-36152: Remove colorizer.ColorDelegator.close_when_done and the
  corresponding argument of .close().  In IDLE, both have always been
  None or False since 2007.

* bpo-32129: Avoid blurry IDLE application icon on macOS with Tk 8.6.
  Patch by Kevin Walzer.

* bpo-36096: Refactor class variables to instance variables in
  colorizer.

* bpo-30348: Increase test coverage of idlelib.autocomplete by 30%.
  Patch by Louie Lu


Tools/Demos
-----------

* bpo-35132: Fix py-list and py-bt commands of python-gdb.py on gdb7.

* bpo-32217: Fix freeze script on Windows.


C API
-----

* bpo-36381: Raise "DeprecationWarning" when ‘#’ formats are used for
  building or parsing values without "PY_SSIZE_T_CLEAN".

* bpo-36142: The whole coreconfig.h header is now excluded from
  Py_LIMITED_API. Move functions definitions into a new internal
  pycore_coreconfig.h header.


Python 3.8.0 alpha 2
====================

*Release date: 2019-02-25*


Core and Builtins
-----------------

* bpo-36052: Raise a "SyntaxError" when assigning a value to
  "__debug__" with the Assignment Operator. Contributed by Stéphane
  Wirtel and Pablo Galindo.

* bpo-36012: Doubled the speed of class variable writes.  When a non-
  dunder attribute was updated, there was an unnecessary call to
  update slots.

* bpo-35942: The error message emitted when returning invalid types
  from "__fspath__" in interfaces that allow passing "PathLike"
  objects has been improved and now it does explain the origin of the
  error.

* bpo-36016: "gc.get_objects" can now receive an optional parameter
  indicating a generation to get objects from. Patch by Pablo Galindo.

* bpo-1054041: When the main interpreter exits due to an uncaught
  KeyboardInterrupt, the process now exits in the appropriate manner
  for its parent process to detect that a SIGINT or ^C terminated the
  process.  This allows shells and batch scripts to understand that
  the user has asked them to stop.

* bpo-35992: Fix "__class_getitem__()" not being called on a class
  with a custom non-subscriptable metaclass.

* bpo-35993: Fix a crash on fork when using subinterpreters.
  Contributed by Stéphane Wirtel

* bpo-35991: Fix a potential double free in Modules/_randommodule.c.

* bpo-35961: Fix a crash in slice_richcompare(): use strong references
  rather than stolen references for the two temporary internal tuples.

* bpo-35911: Enable the creation of cell objects by adding a
  "cell.__new__" method, and expose the type "cell" in "Lib/types.py"
  under the name CellType. Patch by Pierre Glaser.

* bpo-12822: Use monotonic clock for "pthread_cond_timedwait" when
  "pthread_condattr_setclock" and "CLOCK_MONOTONIC" are available.

* bpo-15248: The compiler emits now syntax warnings in the case when a
  comma is likely missed before tuple or list.

* bpo-35886: The implementation of PyInterpreterState has been moved
  into the internal header files (guarded by Py_BUILD_CORE).

* bpo-31506: Clarify the errors reported when "object.__new__" and
  "object.__init__" receive more than one argument. Contributed by
  Sanyam Khurana.

* bpo-35724: Signal-handling is now guaranteed to happen relative to
  the main interpreter.

* bpo-33608: We added a new internal _Py_AddPendingCall() that
  operates relative to the provided interpreter.  This allows us to
  use the existing implementation to ask another interpreter to do
  work that cannot be done in the current interpreter, like decref an
  object the other interpreter owns.  The existing Py_AddPendingCall()
  only operates relative to the main interpreter.

* bpo-33989: Fix a possible crash in "list.sort()" when sorting
  objects with "ob_type->tp_richcompare == NULL".  Patch by Zackery
  Spytz.


Library
-------

* bpo-35512: "unittest.mock.patch.dict()" used as a decorator with
  string target resolves the target during function call instead of
  during decorator construction. Patch by Karthikeyan Singaravelan.

* bpo-36018: Add statistics.NormalDist, a tool for creating and
  manipulating normal distributions of random variable.  Features a
  composite class that treats the mean and standard deviation of
  measurement data as single entity.

* bpo-35904: Added statistics.fmean() as a faster, floating point
  variant of the existing mean() function.

* bpo-35918: Removed broken "has_key" method from
  multiprocessing.managers.SyncManager.dict. Contributed by Rémi
  Lapeyre.

* bpo-18283: Add support for bytes to "shutil.which()".

* bpo-35960: Fix "dataclasses.field()" throwing away empty mapping
  objects passed as metadata.

* bpo-35500: Write expected and actual call parameters on separate
  lines in "unittest.mock.Mock.assert_called_with()" assertion errors.
  Contributed by Susan Su.

* bpo-35931: The "pdb" "debug" command now gracefully handles syntax
  errors.

* bpo-24209: In http.server script, rely on getaddrinfo to bind to
  preferred address based on the bind parameter. Now default bind or
  binding to a name may bind to IPv6 or dual-stack, depending on the
  environment.

* bpo-35321: Set "__spec__.origin" of  "_frozen_importlib" to frozen
  so that it matches the behavior of "_frozen_importlib_external".
  Patch by Nina Zakharenko.

* bpo-35378: Fix a reference issue inside "multiprocessing.Pool" that
  caused the pool to remain alive if it was deleted without being
  closed or terminated explicitly. A new strong reference is added to
  the pool iterators to link the lifetime of the pool to the lifetime
  of its iterators so the pool does not get destroyed if a pool
  iterator is still alive.

* bpo-34294: re module, fix wrong capturing groups in rare cases.
  "re.search()", "re.findall()", "re.sub()" and other functions that
  scan through string looking for a match, should reset capturing
  groups between two match attempts. Patch by Ma Lin.

* bpo-35615: "weakref": Fix a RuntimeError when copying a
  WeakKeyDictionary or a WeakValueDictionary, due to some keys or
  values disappearing while iterating.

* bpo-35606: Implement "math.prod()" as analogous function to "sum()"
  that returns the product of a ‘start’ value (default: 1) times an
  iterable of numbers. Patch by Pablo Galindo.

* bpo-32417: Performing arithmetic between "datetime.datetime"
  subclasses and "datetime.timedelta" now returns an object of the
  same type as the "datetime.datetime" subclass. As a result,
  "datetime.datetime.astimezone()" and alternate constructors like
  "datetime.datetime.now()" and "datetime.fromtimestamp()" called with
  a "tz" argument now *also* retain their subclass.

* bpo-35153: Add *headers* optional keyword-only parameter to
  "xmlrpc.client.ServerProxy", "xmlrpc.client.Transport" and
  "xmlrpc.client.SafeTransport".  Patch by Cédric Krier.

* bpo-34572: Fix C implementation of pickle.loads to use importlib’s
  locking mechanisms, and thereby avoid using partially loaded
  modules. Patch by Tim Burgess.


Documentation
-------------

* bpo-36083: Fix formatting of –check-hash-based-pycs options in the
  manpage Synopsis.

* bpo-36007: Bump minimum sphinx version to 1.8.  Patch by Anthony
  Sottile.

* bpo-22062: Update documentation and docstrings for pathlib. Original
  patch by Mike Short.


Tests
-----

* bpo-27313: Avoid test_ttk_guionly ComboboxTest failure with macOS
  Cocoa Tk.

* bpo-36019: Add test.support.TEST_HTTP_URL and replace references of
  http://www.example.com by this new constant. Contributed by Stéphane
  Wirtel.

* bpo-36037: Fix test_ssl for strict OpenSSL configuration like RHEL8
  strict crypto policy. Use older TLS version for minimum TLS version
  of the server SSL context if needed, to test TLS version older than
  default minimum TLS version.

* bpo-35798: Added "test.support.check_syntax_warning()".

* bpo-35505: Make test_imap4_host_default_value independent on whether
  the local IMAP server is running.

* bpo-35917: multiprocessing: provide unit tests for SyncManager and
  SharedMemoryManager classes + all the shareable types which are
  supposed to be supported by them.  (patch by Giampaolo Rodola)

* bpo-35704: Skip "test_shutil.test_unpack_archive_xztar" to prevent a
  MemoryError on 32-bit AIX when MAXDATA setting is less than
  0x20000000.

  Patch by Michael Felt (aixtools)

* bpo-34720: Assert m_state != NULL to mimic GC traversal functions
  that do not correctly handle module creation when the module state
  has not been created.


Windows
-------

* bpo-35976: Added ARM build support to Windows build files in
  PCBuild.

* bpo-35692: "pathlib" no longer raises when checking file and
  directory existence on drives that are not ready

* bpo-35872: Uses the base Python executable when invoking venv in a
  virtual environment

* bpo-35873: Prevents venv paths being inherited by child processes

* bpo-35299: Fix sysconfig detection of the source directory and
  distutils handling of pyconfig.h during PGO profiling


IDLE
----

* bpo-24310: IDLE – Document settings dialog font tab sample.

* bpo-35833: Revise IDLE doc for control codes sent to Shell. Add a
  code example block.

* bpo-35689: Add docstrings and unittests for colorizer.py.


Python 3.8.0 alpha 1
====================

*Release date: 2019-02-03*


Security
--------

* bpo-35746: [CVE-2019-5010] Fix a NULL pointer deref in ssl module.
  The cert parser did not handle CRL distribution points with empty DP
  or URI correctly. A malicious or buggy certificate can result into
  segfault. Vulnerability (TALOS-2018-0758) reported by Colin Read and
  Nicolas Edet of Cisco.

* bpo-34812: The "-I" command line option (run Python in isolated
  mode) is now also copied by the "multiprocessing" and "distutils"
  modules when spawning child processes. Previously, only "-E" and
  "-s" options (enabled by "-I") were copied.

* bpo-34791: The xml.sax and xml.dom.domreg no longer use environment
  variables to override parser implementations when
  sys.flags.ignore_environment is set by -E or -I arguments.

* bpo-17239: The xml.sax and xml.dom.minidom parsers no longer
  processes external entities by default. External DTD and ENTITY
  declarations no longer load files or create network connections.

* bpo-34623: CVE-2018-14647: The C accelerated _elementtree module now
  initializes hash randomization salt from _Py_HashSecret instead of
  libexpat’s default CSPRNG.

* bpo-34405: Updated to OpenSSL 1.1.0i for Windows builds.

* bpo-33871: Fixed sending the part of the file in "os.sendfile()" on
  macOS.  Using the *trailers* argument could cause sending more bytes
  from the input file than was specified.

* bpo-32533: Fixed thread-safety of error handling in _ssl.

* bpo-33136: Harden ssl module against LibreSSL CVE-2018-8970.
  X509_VERIFY_PARAM_set1_host() is called with an explicit namelen. A
  new test ensures that NULL bytes are not allowed.

* bpo-33001: Minimal fix to prevent buffer overrun in os.symlink on
  Windows

* bpo-32981: Regexes in difflib and poplib were vulnerable to
  catastrophic backtracking. These regexes formed potential DOS
  vectors (REDOS). They have been refactored. This resolves
  CVE-2018-1060 and CVE-2018-1061. Patch by Jamie Davis.

* bpo-28414: The ssl module now allows users to perform their own IDN
  en/decoding when using SNI.


Core and Builtins
-----------------

* bpo-35877: Make parenthesis optional for named expressions in while
  statement. Patch by Karthikeyan Singaravelan.

* bpo-35814: Allow same right hand side expressions in annotated
  assignments as in normal ones. In particular, "x: Tuple[int, int] =
  1, 2" (without parentheses on the right) is now allowed.

* bpo-35766: Add the option to parse PEP 484 type comments in the ast
  module. (Off by default.) This is merging the key functionality of
  the third party fork thereof,
  [typed_ast](https://github.com/python/typed_ast).

* bpo-35713: Reorganize Python initialization to get working
  exceptions and sys.stderr earlier.

* bpo-33416: Add end line and end column position information to the
  Python AST nodes. This is a C-level backwards incompatible change.

* bpo-35720: Fixed a minor memory leak in pymain_parse_cmdline_impl
  function in Modules/main.c

* bpo-35634: "func(**kwargs)" will now raise an error when "kwargs" is
  a mapping containing multiple entries with the same key. An error
  was already raised when other keyword arguments are passed before
  "**kwargs" since Python 3.6.

* bpo-35623: Fix a crash when sorting very long lists. Patch by
  Stephan Hohe.

* bpo-35214: clang Memory Sanitizer build instrumentation was added to
  work around false positives from posix, socket, time, test_io, and
  test_faulthandler.

* bpo-35560: Fix an assertion error in "format()" in debug build for
  floating point formatting with “n” format, zero padding and small
  width. Release build is not impacted. Patch by Karthikeyan
  Singaravelan.

* bpo-35552: Format characters "%s" and "%V" in
  "PyUnicode_FromFormat()" and "%s" in "PyBytes_FromFormat()" no
  longer read memory past the limit if *precision* is specified.

* bpo-35504: Fix segfaults and "SystemError"s when deleting certain
  attributes. Patch by Zackery Spytz.

* bpo-35504: Fixed a SystemError when delete the characters_written
  attribute of an OSError.

* bpo-35494: Improved syntax error messages for unbalanced parentheses
  in f-string.

* bpo-35444: Fixed error handling in pickling methods when fail to
  look up builtin “getattr”. Sped up pickling iterators.

* bpo-35436: Fix various issues with memory allocation error handling.
  Patch by Zackery Spytz.

* bpo-35423: Separate the signal handling trigger in the eval loop
  from the “pending calls” machinery. There is no semantic change and
  the difference in performance is insignificant.

* bpo-35357: Internal attributes’ names of unittest.mock._Call and
  unittest.mock.MagicProxy (name, parent & from_kall) are now prefixed
  with _mock_ in order to prevent clashes with widely used object
  attributes. Fixed minor typo in test function name.

* bpo-35372: Fixed the code page decoder for input longer than 2 GiB
  containing undecodable bytes.

* bpo-35336: Fix PYTHONCOERCECLOCALE=1 environment variable: only
  coerce the C locale if the LC_CTYPE locale is “C”.

* bpo-31241: The *lineno* and *col_offset* attributes of AST nodes for
  list comprehensions, generator expressions and tuples are now point
  to the opening parenthesis or square brace. For tuples without
  parenthesis they point to the position of the first item.

* bpo-33954: For "str.format()", "float.__format__()" and
  "complex.__format__()" methods for non-ASCII decimal point when
  using the “n” formatter.

* bpo-35269: Fix a possible segfault involving a newly created
  coroutine. Patch by Zackery Spytz.

* bpo-35224: Implement **PEP 572** (assignment expressions). Patch by
  Emily Morehouse.

* bpo-32492: Speed up "namedtuple" attribute access by 1.6x using a C
  fast-path for the name descriptors. Patch by Pablo Galindo.

* bpo-35214: Fixed an out of bounds memory access when parsing a
  truncated unicode escape sequence at the end of a string such as
  "'\N'".  It would read one byte beyond the end of the memory
  allocation.

* bpo-35214: The interpreter and extension modules have had
  annotations added so that they work properly under clang’s Memory
  Sanitizer.  A new configure flag –with-memory-sanitizer has been
  added to make test builds of this nature easier to perform.

* bpo-35193: Fix an off by one error in the bytecode peephole
  optimizer where it could read bytes beyond the end of bounds of an
  array when removing unreachable code. This bug was present in every
  release of Python 3.6 and 3.7 until now.

* bpo-35169: Improved error messages for forbidden assignments.

* bpo-34022: Fix handling of hash-based bytecode files in "zipimport".
  Patch by Elvis Pranskevichus.

* bpo-28401: Debug builds will no longer to attempt to import
  extension modules built for the ABI as they were never compatible to
  begin with. Patch by Stefano Rivera.

* bpo-29341: Clarify in the docstrings of "os" methods that path-like
  objects are also accepted as input parameters.

* bpo-35050: "socket": Fix off-by-one bug in length check for "AF_ALG"
  name and type.

* bpo-29743: Raise "ValueError" instead of "OverflowError" in case of
  a negative "_length_" in a "ctypes.Array" subclass.  Also raise
  "TypeError" instead of "AttributeError" for non-integer "_length_".
  Original patch by Oren Milman.

* bpo-16806: Fix "lineno" and "col_offset" for multi-line string
  tokens.

* bpo-35029: "SyntaxWarning" raised as an exception at code generation
  time will be now replaced with a "SyntaxError" for better error
  reporting.

* bpo-34983: Expose "symtable.Symbol.is_nonlocal()" in the symtable
  module. Patch by Pablo Galindo.

* bpo-34974: "bytes" and "bytearray" constructors no longer convert
  unexpected exceptions (e.g. "MemoryError" and "KeyboardInterrupt")
  to "TypeError".

* bpo-34939: Allow annotated names in module namespace that are
  declared global before the annotation happens. Patch by Pablo
  Galindo.

* bpo-34973: Fixed crash in "bytes()" when the "list" argument is
  mutated while it is iterated.

* bpo-34876: The *lineno* and *col_offset* attributes of the AST for
  decorated function and class refer now to the position of the
  corresponding "def", "async def" and "class" instead of the position
  of the first decorator. This leads to more correct line reporting in
  tracing. This is the only case when the position of child AST nodes
  can precede the position of the parent AST node.

* bpo-34879: Fix a possible null pointer dereference in bytesobject.c.
  Patch by Zackery Spytz.

* bpo-34784: Fix the implementation of PyStructSequence_NewType in
  order to create heap allocated StructSequences.

* bpo-32912: A "SyntaxWarning" is now emitted instead of a
  "DeprecationWarning" for invalid escape sequences in string and
  bytes literals.

* bpo-34854: Fixed a crash in compiling string annotations containing
  a lambda with a keyword-only argument that doesn’t have a default
  value.

* bpo-34850: The compiler now produces a "SyntaxWarning" when identity
  checks ("is" and "is not") are used with certain types of literals
  (e.g. strings, ints).  These can often work by accident in CPython,
  but are not guaranteed by the language spec.  The warning advises
  users to use equality tests ("==" and "!=") instead.

* bpo-34824: Fix a possible null pointer dereference in
  Modules/_ssl.c. Patch by Zackery Spytz.

* bpo-30156: The C function "property_descr_get()" uses a “cached”
  tuple to optimize function calls. But this tuple can be discovered
  in debug mode with "sys.getobjects()". Remove the optimization, it’s
  not really worth it and it causes 3 different crashes last years.

* bpo-34762: Fix contextvars C API to use PyObject* pointer types.

* bpo-34751: The hash function for tuples is now based on xxHash which
  gives better collision results on (formerly) pathological cases.
  Additionally, on 64-bit systems it improves tuple hashes in general.
  Patch by Jeroen Demeyer with substantial contributions by Tim
  Peters.

* bpo-34735: Fix a memory leak in Modules/timemodule.c.  Patch by
  Zackery Spytz.

* bpo-34683: Fixed a bug where some SyntaxError error pointed to
  locations that were off-by-one.

* bpo-34651: Only allow the main interpreter to fork.  The avoids the
  possibility of affecting the main interpreter, which is critical to
  operation of the runtime.

* bpo-34653: Remove unused function
  PyParser_SimpleParseStringFilename.

* bpo-32236: Warn that line buffering is not supported if "open()" is
  called with binary mode and "buffering=1".

* bpo-34641: Further restrict the syntax of the left-hand side of
  keyword arguments in function calls. In particular,
  "f((keyword)=arg)" is now disallowed.

* bpo-34637: Make the *start* argument to *sum()* visible as a keyword
  argument.

* bpo-1621: Do not assume signed integer overflow behavior (C
  undefined behavior) when performing set hash table resizing.

* bpo-34588: Fix an off-by-one in the recursive call pruning feature
  of traceback formatting.

* bpo-34485: On Windows, the LC_CTYPE is now set to the user preferred
  locale at startup. Previously, the LC_CTYPE locale was “C” at
  startup, but changed when calling setlocale(LC_CTYPE, “”) or
  setlocale(LC_ALL, “”).

* bpo-34485: Standard streams like sys.stdout now use the
  “surrogateescape” error handler, instead of “strict”, on the POSIX
  locale (when the C locale is not coerced and the UTF-8 Mode is
  disabled).

* bpo-34485: Fix the error handler of standard streams like
  sys.stdout: PYTHONIOENCODING=”:” is now ignored instead of setting
  the error handler to “strict”.

* bpo-34485: Python now gets the locale encoding with C code to
  initialize the encoding of standard streams like sys.stdout.
  Moreover, the encoding is now initialized to the Python codec name
  to get a normalized encoding name and to ensure that the codec is
  loaded. The change avoids importing _bootlocale and _locale modules
  at startup by default.

* bpo-34527: On FreeBSD, Py_DecodeLocale() and Py_EncodeLocale() now
  also forces the ASCII encoding if the LC_CTYPE locale is “POSIX”,
  not only if the LC_CTYPE locale is “C”.

* bpo-34527: The UTF-8 Mode is now also enabled by the “POSIX” locale,
  not only by the “C” locale.

* bpo-34403: On HP-UX with C or POSIX locale,
  sys.getfilesystemencoding() now returns “ascii” instead of “roman8”
  (when the UTF-8 Mode is disabled and the C locale is not coerced).

* bpo-34523: The Python filesystem encoding is now read earlier during
  the Python initialization.

* bpo-12458: Tracebacks show now correct line number for
  subexpressions in multiline expressions. Tracebacks show now the
  line number of the first line for multiline expressions instead of
  the line number of the last subexpression.

* bpo-34408: Prevent a null pointer dereference and resource leakage
  in "PyInterpreterState_New()".

* bpo-34400: Fix undefined behavior in parsetok.c.  Patch by Zackery
  Spytz.

* bpo-33073: Added as_integer_ratio to ints to make them more
  interoperable with floats.

* bpo-34377: Update valgrind suppression list to use
  "_PyObject_Free"/"_PyObject_Realloc" instead of
  "PyObject_Free"/"PyObject_Realloc".

* bpo-34353: Added the “socket” option in the "stat.filemode()" Python
  implementation to match the C implementation.

* bpo-34320: Fix "dict(od)" didn’t copy iteration order of
  OrderedDict.

* bpo-34113: Fixed crash on debug builds when opcode stack was
  adjusted with negative numbers. Patch by Constantin Petrisor.

* bpo-34100: Compiler now merges constants in tuples and frozensets
  recursively. Code attributes like "co_names" are merged too.

* bpo-34151: Performance of list concatenation, repetition and slicing
  operations is slightly improved. Patch by Sergey Fedoseev.

* bpo-34170: -X dev: it is now possible to override the memory
  allocator using PYTHONMALLOC even if the developer mode is enabled.

* bpo-33237: Improved "AttributeError" message for partially
  initialized module.

* bpo-34149: Fix min and max functions to get default behavior when
  key is None.

* bpo-34125: Profiling of unbound built-in methods now works when
  "**kwargs" is given.

* bpo-34141: Optimized pickling atomic types (None, bool, int, float,
  bytes, str).

* bpo-34126: Fix crashes when profiling certain invalid calls of
  unbound methods. Patch by Jeroen Demeyer.

* bpo-24618: Fixed reading invalid memory when create the code object
  with too small varnames tuple or too large argument counts.

* bpo-34068: In "io.IOBase.close()", ensure that the "closed"
  attribute is not set with a live exception. Patch by Zackery Spytz
  and Serhiy Storchaka.

* bpo-34087: Fix buffer overflow while converting unicode to numeric
  values.

* bpo-34080: Fixed a memory leak in the compiler when it raised some
  uncommon errors during tokenizing.

* bpo-34066: Disabled interruption by Ctrl-C between calling "open()"
  and entering a **with** block in "with open()".

* bpo-34042: Fix dict.copy() to maintain correct total refcount (as
  reported by sys.gettotalrefcount()).

* bpo-33418: Fix potential memory leak in function object when it
  creates reference cycle.

* bpo-33985: Implement contextvars.ContextVar.name attribute.

* bpo-33956: Update vendored Expat library copy to version 2.2.5.

* bpo-24596: Decref the module object in "PyRun_SimpleFileExFlags()"
  before calling "PyErr_Print()".  Patch by Zackery Spytz.

* bpo-33451: Close directly executed pyc files before calling
  "PyEval_EvalCode()".

* bpo-1617161: The hash of "BuiltinMethodType" instances (methods of
  built-in classes) now depends on the hash of the identity of
  *__self__* instead of its value. The hash and equality of
  "ModuleType" and "MethodWrapperType" instances (methods of user-
  defined classes and some methods of built-in classes like
  "str.__add__") now depend on the hash and equality of the identity
  of *__self__* instead of its value. "MethodWrapperType" instances no
  longer support ordering.

* bpo-33824: Fix “LC_ALL=C python3.7 -V”: reset properly the command
  line parser when the encoding changes after reading the Python
  configuration.

* bpo-33803: Fix a crash in hamt.c caused by enabling GC tracking for
  an object that hadn’t all of its fields set to NULL.

* bpo-33738: Seven macro incompatibilities with the Limited API were
  fixed, and the macros "PyIter_Check()", "PyIndex_Check()" and
  "PyExceptionClass_Name()" were added as functions. A script for
  automatic macro checks was added.

* bpo-33786: Fix asynchronous generators to handle GeneratorExit in
  athrow() correctly

* bpo-30167: "PyRun_SimpleFileExFlags" removes "__cached__" from
  module in addition to "__file__".

* bpo-33706: Fix a crash in Python initialization when parsing the
  command line options. Thanks Christoph Gohlke for the bug report and
  the fix!

* bpo-33597: Reduce "PyGC_Head" size from 3 words to 2 words.

* bpo-30654: Fixed reset of the SIGINT handler to SIG_DFL on
  interpreter shutdown even when there was a custom handler set
  previously. Patch by Philipp Kerling.

* bpo-33622: Fixed a leak when the garbage collector fails to add an
  object with the "__del__" method or referenced by it into the
  "gc.garbage" list. "PyGC_Collect()" can now be called when an
  exception is set and preserves it.

* bpo-33462: Make dict and dict views reversible. Patch by Rémi
  Lapeyre.

* bpo-23722: A "RuntimeError" is now raised when the custom metaclass
  doesn’t provide the "__classcell__" entry in the namespace passed to
  "type.__new__".  A "DeprecationWarning" was emitted in Python
  3.6–3.7.

* bpo-33499: Add "PYTHONPYCACHEPREFIX" environment variable and "-X"
  "pycache_prefix" command-line option to set an alternate root
  directory for writing module bytecode cache files.

* bpo-25711: The "zipimport" module has been rewritten in pure Python.

* bpo-33509: Fix module_globals parameter of warnings.warn_explicit():
  don’t crash if module_globals is not a dict.

* bpo-31849: Fix signed/unsigned comparison warning in pyhash.c.

* bpo-33475: Fixed miscellaneous bugs in converting annotations to
  strings and optimized parentheses in the string representation.

* bpo-20104: Added support for the "setpgroup", "resetids",
  "setsigmask", "setsigdef" and "scheduler" parameters of
  "posix_spawn". Patch by Pablo Galindo.

* bpo-33391: Fix a leak in set_symmetric_difference().

* bpo-33363: Raise a SyntaxError for "async with" and "async for"
  statements outside of async functions.

* bpo-28055: Fix unaligned accesses in siphash24(). Patch by Rolf Eike
  Beer.

* bpo-33128: Fix a bug that causes PathFinder to appear twice on
  sys.meta_path. Patch by Pablo Galindo Salgado.

* bpo-33331: Modules imported last are now cleared first at
  interpreter shutdown.

* bpo-33312: Fixed clang ubsan (undefined behavior sanitizer) warnings
  in dictobject.c by adjusting how the internal struct _dictkeysobject
  shared keys structure is declared.

* bpo-33305: Improved syntax error messages for invalid numerical
  literals.

* bpo-33306: Improved syntax error messages for unbalanced
  parentheses.

* bpo-33234: The list constructor will pre-size and not over-allocate
  when the input length is known.

* bpo-33270: Intern the names for all anonymous code objects.  Patch
  by Zackery Spytz.

* bpo-30455: The C and Python code and the documentation related to
  tokens are now generated from a single source file "Grammar/Tokens".

* bpo-33176: Add a "toreadonly()" method to memoryviews.

* bpo-33231: Fix potential memory leak in "normalizestring()".

* bpo-33205: Change dict growth function from
  "round_up_to_power_2(used*2+hashtable_size/2)" to
  "round_up_to_power_2(used*3)".  Previously, dict is shrinked only
  when "used == 0". Now dict has more chance to be shrinked.

* bpo-29922: Improved error messages in ‘async with’ when
  "__aenter__()" or "__aexit__()" return non-awaitable object.

* bpo-33199: Fix "ma_version_tag" in dict implementation is
  uninitialized when copying from key-sharing dict.

* bpo-33053: When using the -m switch, sys.path[0] is now explicitly
  expanded as the *starting* working directory, rather than being left
  as the empty path (which allows imports from the current working
  directory at the time of the import)

* bpo-33138: Changed standard error message for non-pickleable and
  non-copyable types. It now says “cannot pickle” instead of “can’t
  pickle” or “cannot serialize”.

* bpo-33018: Improve consistency of errors raised by "issubclass()"
  when called with a non-class and an abstract base class as the first
  and second arguments, respectively. Patch by Josh Bronson.

* bpo-33083: "math.factorial" no longer accepts arguments that are not
  int-like. Patch by Pablo Galindo.

* bpo-33041: Added new opcode "END_ASYNC_FOR" and fixes the following
  issues:

  * Setting global "StopAsyncIteration" no longer breaks "async for"
    loops.

  * Jumping into an "async for" loop is now disabled.

  * Jumping out of an "async for" loop no longer corrupts the stack.

* bpo-25750: Fix rare Python crash due to bad refcounting in
  "type_getattro()" if a descriptor deletes itself from the class.
  Patch by Jeroen Demeyer.

* bpo-33041: Fixed bytecode generation for “async for” with a complex
  target. A StopAsyncIteration raised on assigning or unpacking will
  be now propagated instead of stopping the iteration.

* bpo-33026: Fixed jumping out of “with” block by setting f_lineno.

* bpo-33005: Fix a crash on fork when using a custom memory allocator
  (ex: using PYTHONMALLOC env var). _PyGILState_Reinit() and
  _PyInterpreterState_Enable() now use the default RAW memory
  allocator to allocate a new interpreters mutex on fork.

* bpo-32911: Due to unexpected compatibility issues discovered during
  downstream beta testing, reverted bpo-29463. "docstring" field is
  removed from Module, ClassDef, FunctionDef, and AsyncFunctionDef ast
  nodes which was added in 3.7a1.  Docstring expression is restored as
  a first statement in their body. Based on patch by Inada Naoki.

* bpo-17288: Prevent jumps from ‘return’ and ‘exception’ trace events.

* bpo-32946: Importing names from already imported module with “from …
  import …” is now 30% faster if the module is not a package.

* bpo-32932: Make error message more revealing when there are non-str
  objects in "__all__".

* bpo-32925: Optimized iterating and containing test for literal lists
  consisting of non-constants: "x in [a, b]" and "for x in [a, b]".
  The case of all constant elements already was optimized.

* bpo-32889: Update Valgrind suppression list to account for the
  rename of "Py_ADDRESS_IN_RANG" to "address_in_range".

* bpo-32836: Don’t use temporary variables in cases of list/dict/set
  comprehensions

* bpo-31356: Remove the new API added in bpo-31356
  (gc.ensure_disabled() context manager).

* bpo-32305: For namespace packages, ensure that both "__file__" and
  "__spec__.origin" are set to None.

* bpo-32303: Make sure "__spec__.loader" matches "__loader__" for
  namespace packages.

* bpo-32711: Fix the warning messages for Python/ast_unparse.c. Patch
  by Stéphane Wirtel

* bpo-32583: Fix possible crashing in builtin Unicode decoders caused
  by write out-of-bound errors when using customized decode error
  handlers.

* bpo-32489: A "continue" statement is now allowed in the "finally"
  clause.

* bpo-17611: Simplified the interpreter loop by moving the logic of
  unrolling the stack of blocks into the compiler. The compiler emits
  now explicit instructions for adjusting the stack of values and
  calling the cleaning up code for "break", "continue" and "return".

  Removed opcodes "BREAK_LOOP", "CONTINUE_LOOP", "SETUP_LOOP" and
  "SETUP_EXCEPT". Added new opcodes "ROT_FOUR", "BEGIN_FINALLY" and
  "CALL_FINALLY" and "POP_FINALLY". Changed the behavior of
  "END_FINALLY" and "WITH_CLEANUP_START".

* bpo-32285: New function unicodedata.is_normalized, which can check
  whether a string is in a specific normal form.

* bpo-10544: Yield expressions are now disallowed in comprehensions
  and generator expressions except the expression for the outermost
  iterable.

* bpo-32117: Iterable unpacking is now allowed without parentheses in
  yield and return statements, e.g. "yield 1, 2, 3, *rest". Thanks to
  David Cuthbert for the change and Jordan Chapman for added tests.

* bpo-31902: Fix the "col_offset" attribute for ast nodes
  "ast.AsyncFor", "ast.AsyncFunctionDef", and "ast.AsyncWith".
  Previously, "col_offset" pointed to the keyword after "async".

* bpo-25862: Fix assertion failures in the "tell()" method of
  "io.TextIOWrapper". Patch by Zackery Spytz.

* bpo-21983: Fix a crash in "ctypes.cast()" in case the type argument
  is a ctypes structured data type. Patch by Eryk Sun and Oren Milman.

* bpo-31577: Fix a crash in "os.utime()" in case of a bad ns argument.
  Patch by Oren Milman.

* bpo-29832: Remove references to ‘getsockaddrarg’ from various socket
  error messages. Patch by Oren Milman.


Library
-------

* bpo-35845: Add ‘order’ parameter to memoryview.tobytes().

* bpo-35864: The _asdict() method for collections.namedtuple now
  returns a regular dict instead of an OrderedDict.

* bpo-35537: An ExitStack is now used internally within
  subprocess.Popen to clean up pipe file handles. No behavior change
  in normal operation. But if closing one handle were ever to cause an
  exception, the others will now be closed instead of leaked.  (patch
  by Giampaolo Rodola)

* bpo-35847: RISC-V needed the CTYPES_PASS_BY_REF_HACK.  Fixes ctypes
  Structure test_pass_by_value.

* bpo-35813: Shared memory submodule added to multiprocessing to avoid
  need for serialization between processes

* bpo-35780: Fix lru_cache() errors arising in recursive, reentrant,
  or multi-threaded code. These errors could result in orphan links
  and in the cache being trapped in a state with fewer than the
  specified maximum number of links. Fix handling of negative maxsize
  which should have been treated as zero. Fix errors in toggling the
  “full” status flag. Fix misordering of links when errors are
  encountered.  Sync-up the C code and pure Python code for the space
  saving path in functions with a single positional argument. In this
  common case, the space overhead of an lru cache entry is reduced by
  almost half.  Fix counting of cache misses. In error cases, the miss
  count was out of sync with the actual number of times the underlying
  user function was called.

* bpo-35537: "os.posix_spawn()" and "os.posix_spawnp()" now have a
  *setsid* parameter.

* bpo-23846: "asyncio.ProactorEventLoop" now catches and logs send
  errors when the self-pipe is full.

* bpo-34323: "asyncio": Enhance "IocpProactor.close()" log: wait 1
  second before the first log, then log every second. Log also the
  number of seconds since "close()" was called.

* bpo-35674: Add a new "os.posix_spawnp()" function. Patch by Joannah
  Nanjekye.

* bpo-35733: "ast.Constant(boolean)" no longer an instance of
  "ast.Num".  Patch by Anthony Sottile.

* bpo-35726: QueueHandler.prepare() now makes a copy of the record
  before modifying and enqueueing it, to avoid affecting other
  handlers in the chain.

* bpo-35719: Sped up multi-argument "math" functions atan2(),
  copysign(), remainder() and hypot() by 1.3–2.5 times.

* bpo-35717: Fix KeyError exception raised when using enums and
  compile. Patch contributed by Rémi Lapeyre.

* bpo-35699: Fixed detection of Visual Studio Build Tools 2017 in
  distutils

* bpo-32710: Fix memory leaks in asyncio ProactorEventLoop on
  overlapped operation failure.

* bpo-35702: The "time.CLOCK_UPTIME_RAW" constant is now available for
  macOS 10.12.

* bpo-32710: Fix a memory leak in asyncio in the ProactorEventLoop
  when "ReadFile()" or "WSASend()" overlapped operation fail
  immediately: release the internal buffer.

* bpo-35682: Fix "asyncio.ProactorEventLoop.sendfile()": don’t attempt
  to set the result of an internal future if it’s already done.

* bpo-35283: Add a deprecated warning for the
  "threading.Thread.isAlive()" method. Patch by Dong-hee Na.

* bpo-35664: Improve operator.itemgetter() performance by 33% with
  optimized argument handling and with adding a fast path for the
  common case of a single non-negative integer index into a tuple
  (which is the typical use case in the standard library).

* bpo-35643: Fixed a SyntaxWarning: invalid escape sequence in
  Modules/_sha3/cleanup.py. Patch by Mickaël Schoentgen.

* bpo-35619: Improved support of custom data descriptors in "help()"
  and "pydoc".

* bpo-28503: The "crypt" module now internally uses the "crypt_r()"
  library function instead of "crypt()" when available.

* bpo-35614: Fixed help() on metaclasses. Patch by Sanyam Khurana.

* bpo-35568: Expose "raise(signum)" as "raise_signal"

* bpo-35588: The floor division and modulo operations and the
  "divmod()" function on "fractions.Fraction" types are 2–4x faster.
  Patch by Stefan Behnel.

* bpo-35585: Speed-up building enums by value, e.g.
  http.HTTPStatus(200).

* bpo-30561: random.gammavariate(1.0, beta) now computes the same
  result as random.expovariate(1.0 / beta).  This synchronizes the two
  algorithms and eliminates some idiosyncrasies in the old
  implementation.  It does however produce a difference stream of
  random variables than it used to.

* bpo-35537: The "subprocess" module can now use the
  "os.posix_spawn()" function in some cases for better performance.

* bpo-35526: Delaying the ‘joke’ of barry_as_FLUFL.mandatory to Python
  version 4.0

* bpo-35523: Remove "ctypes" callback workaround: no longer create a
  callback at startup. Avoid SELinux alert on "import ctypes" and
  "import uuid".

* bpo-31784: "uuid.uuid1()" now calls "time.time_ns()" rather than
  "int(time.time() * 1e9)".

* bpo-35513: "TextTestRunner" of "unittest.runner" now uses
  "time.perf_counter()" rather than "time.time()" to measure the
  execution time of a test: "time.time()" can go backwards, whereas
  "time.perf_counter()" is monotonic.

* bpo-35502: Fixed reference leaks in
  "xml.etree.ElementTree.TreeBuilder" in case of unfinished building
  of the tree (in particular when an error was raised during parsing
  XML).

* bpo-35348: Make "platform.architecture()" parsing of "file" command
  output more reliable: add the "-b" option to the "file" command to
  omit the filename, force the usage of the C locale, and search also
  the “shared object” pattern.

* bpo-35491: "multiprocessing": Add "Pool.__repr__()" and enhance
  "BaseProcess.__repr__()" (add pid and parent pid) to ease debugging.
  Pool state constant values are now strings instead of integers, for
  example "RUN" value becomes "'RUN'" instead of "0".

* bpo-35477: "multiprocessing.Pool.__enter__()" now fails if the pool
  is not running: "with pool:" fails if used more than once.

* bpo-31446: Copy command line that was passed to CreateProcessW since
  this function can change the content of the input buffer.

* bpo-35471: Python 2.4 dropped MacOS 9 support. The macpath module
  was deprecated in Python 3.7. The module is now removed.

* bpo-23057: Unblock Proactor event loop when keyboard interrupt is
  received on Windows

* bpo-35052: Fix xml.dom.minidom cloneNode() on a document with an
  entity: pass the correct arguments to the user data handler of an
  entity.

* bpo-20239: Allow repeated assignment deletion of
  "unittest.mock.Mock" attributes. Patch by Pablo Galindo.

* bpo-17185: Set "__signature__" on mock for "inspect" to get
  signature. Patch by Karthikeyan Singaravelan.

* bpo-35445: Memory errors during creating posix.environ no longer
  ignored.

* bpo-35415: Validate fileno= argument to socket.socket().

* bpo-35424: "multiprocessing.Pool" destructor now emits
  "ResourceWarning" if the pool is still running.

* bpo-35330: When a "Mock" instance was used to wrap an object, if
  "side_effect" is used in one of the mocks of it methods, don’t call
  the original implementation and return the result of using the side
  effect the same way that it is done with return_value.

* bpo-35346: Drop Mac OS 9 and Rhapsody support from the "platform"
  module. Rhapsody last release was in 2000. Mac OS 9 last release was
  in 2001.

* bpo-10496: "check_environ()" of "distutils.utils" now catches
  "KeyError" on calling "pwd.getpwuid()": don’t create the "HOME"
  environment variable in this case.

* bpo-10496: "posixpath.expanduser()" now returns the input *path*
  unchanged if the "HOME" environment variable is not set and the
  current user has no home directory (if the current user identifier
  doesn’t exist in the password database). This change fix the "site"
  module if the current user doesn’t exist in the password database
  (if the user has no home directory).

* bpo-35389: "platform.libc_ver()" now uses
  "os.confstr('CS_GNU_LIBC_VERSION')" if available and the
  *executable* parameter is not set.

* bpo-35394: Add empty slots to asyncio abstract protocols.

* bpo-35310: Fix a bug in "select.select()" where, in some cases, the
  file descriptor sequences were returned unmodified after a signal
  interruption, even though the file descriptors might not be ready
  yet. "select.select()" will now always return empty lists if a
  timeout has occurred.  Patch by Oran Avraham.

* bpo-35380: Enable TCP_NODELAY on Windows for proactor asyncio event
  loop.

* bpo-35341: Add generic version of "collections.OrderedDict" to the
  "typing" module. Patch by Ismo Toijala.

* bpo-35371: Fixed possible crash in "os.utime()" on Windows when pass
  incorrect arguments.

* bpo-35346: "platform.uname()" now redirects "stderr" to "os.devnull"
  when running external programs like "cmd /c ver".

* bpo-35066: Previously, calling the strftime() method on a datetime
  object with a trailing ‘%’ in the format string would result in an
  exception. However, this only occurred when the datetime C module
  was being used; the python implementation did not match this
  behavior. Datetime is now PEP-399 compliant, and will not throw an
  exception on a trailing ‘%’.

* bpo-35345: The function "platform.popen" has been removed, it was
  deprecated since Python 3.3: use "os.popen()" instead.

* bpo-35344: On macOS, "platform.platform()" now uses
  "platform.mac_ver()", if it returns a non-empty release string, to
  get the macOS version rather than the darwin version.

* bpo-35312: Make "lib2to3.pgen2.parse.ParseError" round-trip pickle-
  able. Patch by Anthony Sottile.

* bpo-35308: Fix regression in "webbrowser" where default browsers may
  be preferred over browsers in the "BROWSER" environment variable.

* bpo-24746: Avoid stripping trailing whitespace in doctest fancy
  diff. Original patch by R. David Murray & Jairo Trad. Enhanced by
  Sanyam Khurana.

* bpo-28604: "locale.localeconv()" now sets temporarily the "LC_CTYPE"
  locale to the "LC_MONETARY" locale if the two locales are different
  and monetary strings are non-ASCII. This temporary change affects
  other threads.

* bpo-35277: Update ensurepip to install pip 18.1 and setuptools
  40.6.2.

* bpo-24209: Adds IPv6 support when invoking http.server directly.

* bpo-35226: Recursively check arguments when testing for equality of
  "unittest.mock.call" objects and add note that tracking of
  parameters used to create ancestors of mocks in "mock_calls" is not
  possible.

* bpo-29564: The warnings module now suggests to enable tracemalloc if
  the source is specified, the tracemalloc module is available, but
  tracemalloc is not tracing memory allocations.

* bpo-35189: Modify the following fnctl function to retry if
  interrupted by a signal (EINTR): flock, lockf, fnctl

* bpo-30064: Use add_done_callback() in sock_* asyncio API to
  unsubscribe reader/writer early on calcellation.

* bpo-35186: Removed the “built with” comment added when "setup.py
  upload" is used with either "bdist_rpm" or "bdist_dumb".

* bpo-35152: Allow sending more than 2 GB at once on a multiprocessing
  connection on non-Windows systems.

* bpo-35062: Fix incorrect parsing of
  "_io.IncrementalNewlineDecoder"’s *translate* argument.

* bpo-35065: Remove "StreamReaderProtocol._untrack_reader". The call
  to "_untrack_reader" is currently performed too soon, causing the
  protocol to forget about the reader before "connection_lost" can run
  and feed the EOF to the reader.

* bpo-34160: ElementTree and minidom now preserve the attribute order
  specified by the user.

* bpo-35079: Improve difflib.SequenceManager.get_matching_blocks doc
  by adding ‘non-overlapping’ and changing ‘!=’ to ‘<’.

* bpo-33710: Deprecated "l*gettext()" functions and methods in the
  "gettext" module. They return encoded bytes instead of Unicode
  strings and are artifacts from Python 2 times. Also deprecated
  functions and methods related to setting the charset for
  "l*gettext()" functions and methods.

* bpo-35017: "socketserver.BaseServer.serve_forever()" now exits
  immediately if it’s "shutdown()" method is called while it is
  polling for new events.

* bpo-35024: "importlib" no longer logs "wrote" redundantly after
  "(created|could not create)" is already logged. Patch by Quentin
  Agren.

* bpo-35047: "unittest.mock" now includes mock calls in exception
  messages if "assert_not_called", "assert_called_once", or
  "assert_called_once_with" fails. Patch by Petter Strandmark.

* bpo-31047: Fix "ntpath.abspath" regression where it didn’t remove a
  trailing separator on Windows. Patch by Tim Graham.

* bpo-35053: tracemalloc now tries to update the traceback when an
  object is reused from a “free list” (optimization for faster object
  creation, used by the builtin list type for example).

* bpo-31553: Add the –json-lines option to json.tool. Patch by
  hongweipeng.

* bpo-34794: Fixed a leak in Tkinter when pass the Python wrapper
  around Tcl_Obj back to Tcl/Tk.

* bpo-34909: Enum: fix grandchildren subclassing when parent mixed
  with concrete data types.

* bpo-35022: "unittest.mock.MagicMock" now supports the "__fspath__"
  method (from "os.PathLike").

* bpo-35008: Fixed references leaks when call the "__setstate__()"
  method of "xml.etree.ElementTree.Element" in the C implementation
  for already initialized element.

* bpo-23420: Verify the value for the parameter ‘-s’ of the cProfile
  CLI. Patch by Robert Kuska

* bpo-33947: dataclasses now handle recursive reprs without raising
  RecursionError.

* bpo-34890: Make "inspect.iscoroutinefunction()",
  "inspect.isgeneratorfunction()" and "inspect.isasyncgenfunction()"
  work with "functools.partial()". Patch by Pablo Galindo.

* bpo-34521: Use "socket.CMSG_SPACE()" to calculate ancillary data
  size instead of "socket.CMSG_LEN()" in
  "multiprocessing.reduction.recvfds()" as **RFC 3542** requires the
  use of the former for portable applications.

* bpo-31522: The "mailbox.mbox.get_string" function *from_* parameter
  can now successfully be set to a non-default value.

* bpo-34970: Protect tasks weak set manipulation in
  "asyncio.all_tasks()"

* bpo-34969: gzip: Add –fast, –best on the gzip CLI, these parameters
  will be used for the fast compression method (quick) or the best
  method compress (slower, but smaller file). Also, change the default
  compression level to 6 (tradeoff).

* bpo-16965: The *2to3* "execfile" fixer now opens the file with mode
  "'rb'".  Patch by Zackery Spytz.

* bpo-34966: "pydoc" now supports aliases not only to methods defined
  in the end class, but also to inherited methods.  The docstring is
  not duplicated for aliases.

* bpo-34926: "mimetypes.MimeTypes.guess_type()" now accepts *path-like
  object* in addition to url strings. Patch by Mayank Asthana.

* bpo-23831: Add "moveto()" method to the "tkinter.Canvas" widget.
  Patch by Juliette Monsel.

* bpo-34941: Methods "find()", "findtext()" and "findall()" of the
  "Element" class in the "xml.etree.ElementTree" module are now able
  to find children which are instances of "Element" subclasses.

* bpo-32680: "smtplib.SMTP" objects now always have a "sock" attribute
  present

* bpo-34769: Fix for async generators not finalizing when event loop
  is in debug mode and garbage collector runs in another thread.

* bpo-34936: Fix "TclError" in "tkinter.Spinbox.selection_element()".
  Patch by Juliette Monsel.

* bpo-34829: Add methods "selection_from", "selection_range",
  "selection_present" and "selection_to" to the "tkinter.Spinbox" for
  consistency with the "tkinter.Entry" widget. Patch by Juliette
  Monsel.

* bpo-34911: Added *secure_protocols* argument to
  *http.cookiejar.DefaultCookiePolicy* to allow for tweaking of
  protocols and also to add support by default for *wss*, the secure
  websocket protocol.

* bpo-34922: Fixed integer overflow in the "digest()" and
  "hexdigest()" methods for the SHAKE algorithm in the "hashlib"
  module.

* bpo-34925: 25% speedup in argument parsing for the functions in the
  bisect module.

* bpo-34900: Fixed "unittest.TestCase.debug()" when used to call test
  methods with subtests.  Patch by Bruno Oliveira.

* bpo-34844: logging.Formatter enhancement - Ensure styles and fmt
  matches in logging.Formatter - Added validate method in each format
  style class: StrFormatStyle, PercentStyle, StringTemplateStyle. -
  This method is called in the constructor of logging.Formatter class
  - Also re-raise the KeyError in the format method of each style
  class, so it would a bit clear that it’s an error with the invalid
  format fields.

* bpo-34897: Adjust test.support.missing_compiler_executable check so
  that a nominal command name of “” is ignored. Patch by Michael Felt.

* bpo-34871: Fix inspect module polluted "sys.modules" when parsing
  "__text_signature__" of callable.

* bpo-34898: Add "mtime" argument to "gzip.compress" for reproducible
  output. Patch by Guo Ci Teo.

* bpo-28441: On Cygwin and MinGW, ensure that "sys.executable" always
  includes the full filename in the path, including the ".exe" suffix
  (unless it is a symbolic link).

* bpo-34866: Adding "max_num_fields" to "cgi.FieldStorage" to make DOS
  attacks harder by limiting the number of "MiniFieldStorage" objects
  created by "FieldStorage".

* bpo-34711: http.server ensures it reports HTTPStatus.NOT_FOUND when
  the local path ends with “/” and is not a directory, even if the
  underlying OS (e.g. AIX) accepts such paths as a valid file
  reference. Patch by Michael Felt.

* bpo-34872: Fix self-cancellation in C implementation of asyncio.Task

* bpo-34849: Don’t log waiting for "selector.select" in asyncio loop
  iteration. The waiting is pretty normal for any asyncio program,
  logging its time just adds a noise to logs without any useful
  information provided.

* bpo-34022: The "SOURCE_DATE_EPOCH" environment variable no longer
  overrides the value of the *invalidation_mode* argument to
  "py_compile.compile()", and determines its default value instead.

* bpo-34819: Use a monotonic clock to compute timeouts in
  "Executor.map()" and "as_completed()", in order to prevent timeouts
  from deviating when the system clock is adjusted.

* bpo-34758: Add .wasm -> application/wasm to list of recognized file
  types and content type headers

* bpo-34789: "xml.sax.make_parser()" now accepts any iterable as its
  *parser_list* argument.  Patch by Andrés Delfino.

* bpo-34334: In "QueueHandler", clear "exc_text" from "LogRecord" to
  prevent traceback from being written twice.

* bpo-34687: On Windows, asyncio now uses ProactorEventLoop, instead
  of SelectorEventLoop, by default.

* bpo-5950: Support reading zip files with archive comments in
  "zipimport".

* bpo-32892: The parser now represents all constants as "ast.Constant"
  instead of using specific constant AST types ("Num", "Str", "Bytes",
  "NameConstant" and "Ellipsis"). These classes are considered
  deprecated and will be removed in future Python versions.

* bpo-34728: Add deprecation warning when "loop" is used in methods:
  "asyncio.sleep", "asyncio.wait" and "asyncio.wait_for".

* bpo-34738: ZIP files created by "distutils" will now include entries
  for directories.

* bpo-34659: Add an optional *initial* argument to
  itertools.accumulate().

* bpo-29577: Support multiple mixin classes when creating Enums.

* bpo-34670: Add SSLContext.post_handshake_auth and
  SSLSocket.verify_client_post_handshake for TLS 1.3’s post handshake
  authentication feature.

* bpo-32718: The Activate.ps1 script from venv works with PowerShell
  Core 6.1 and is now available under all operating systems.

* bpo-31177: Fix bug that prevented using "reset_mock" on mock
  instances with deleted attributes

* bpo-34672: Add a workaround, so the "'Z'" "time.strftime()"
  specifier on the musl C library can work in some cases.

* bpo-34666: Implement "asyncio.StreamWriter.awrite" and
  "asyncio.StreamWriter.aclose()" coroutines.  Methods are needed for
  providing a consistent stream API with control flow switched on by
  default.

* bpo-6721: Acquire the logging module’s commonly used internal locks
  while fork()ing to avoid deadlocks in the child process.

* bpo-34658: Fix a rare interpreter unhandled exception state
  SystemError only seen when using subprocess with a preexec_fn while
  an after_parent handler has been registered with os.register_at_fork
  and the fork system call fails.

* bpo-34652: Ensure "os.lchmod()" is never defined on Linux.

* bpo-34638: Store a weak reference to stream reader to break strong
  references loop between reader and protocol.  It allows to detect
  and close the socket if the stream is deleted (garbage collected)
  without "close()" call.

* bpo-34536: "Enum._missing_":  raise "ValueError" if None returned
  and "TypeError" if non-member is returned.

* bpo-34636: Speed up re scanning of many non-matching characters for
  s w and d within bytes objects. (microoptimization)

* bpo-24412: Add "addModuleCleanup()" and "addClassCleanup()" to
  unittest to support cleanups for "setUpModule()" and "setUpClass()".
  Patch by Lisa Roach.

* bpo-34630: Don’t log SSL certificate errors in asyncio code
  (connection error logging is skipped already).

* bpo-32490: Prevent filename duplication in "subprocess" exception
  messages.  Patch by Zackery Spytz.

* bpo-34363: dataclasses.asdict() and .astuple() now handle
  namedtuples correctly.

* bpo-34625: Update vendorized expat library version to 2.2.6.

* bpo-32270: The subprocess module no longer mistakenly closes
  redirected fds even when they were in pass_fds when outside of the
  default {0, 1, 2} set.

* bpo-34622: Create a dedicated "asyncio.CancelledError",
  "asyncio.InvalidStateError" and "asyncio.TimeoutError" exception
  classes.  Inherit them from corresponding exceptions from
  "concurrent.futures" package. Extract "asyncio" exceptions into a
  separate file.

* bpo-34610: Fixed iterator of "multiprocessing.managers.DictProxy".

* bpo-34421: Fix distutils logging for non-ASCII strings.  This caused
  installation issues on Windows.

* bpo-34604: Fix possible mojibake in the error message of
  "pwd.getpwnam" and "grp.getgrnam" using string representation
  because of invisible characters or trailing whitespaces. Patch by
  William Grzybowski.

* bpo-30977: Make uuid.UUID use "__slots__" to reduce its memory
  footprint. Based on original patch by Wouter Bolsterlee.

* bpo-34574: OrderedDict iterators are not exhausted during pickling
  anymore. Patch by Sergey Fedoseev.

* bpo-8110: Refactored "subprocess" to check for Windows-specific
  modules rather than "sys.platform == 'win32'".

* bpo-34530: "distutils.spawn.find_executable()" now falls back on
  "os.defpath" if the "PATH" environment variable is not set.

* bpo-34563: On Windows, fix multiprocessing.Connection for very large
  read: fix _winapi.PeekNamedPipe() and _winapi.ReadFile() for read
  larger than INT_MAX (usually "2**31-1").

* bpo-34558: Correct typo in Lib/ctypes/_aix.py

* bpo-34282: Move "Enum._convert" to "EnumMeta._convert_" and fix enum
  members getting shadowed by parent attributes.

* bpo-22872: When the queue is closed, "ValueError" is now raised by
  "multiprocessing.Queue.put()" and "multiprocessing.Queue.get()"
  instead of "AssertionError" and "OSError", respectively. Patch by
  Zackery Spytz.

* bpo-34515: Fix parsing non-ASCII identifiers in
  "lib2to3.pgen2.tokenize" (PEP 3131).

* bpo-13312: Avoids a possible integer underflow (undefined behavior)
  in the time module’s year handling code when passed a very low
  negative year value.

* bpo-34472: Improved compatibility for streamed files in "zipfile".
  Previously an optional signature was not being written and certain
  ZIP applications were not supported. Patch by Silas Sewell.

* bpo-34454: Fix the .fromisoformat() methods of datetime types
  crashing when given unicode with non-UTF-8-encodable code points.
  Specifically, datetime.fromisoformat() now accepts surrogate unicode
  code points used as the separator. Report and tests by Alexey
  Izbyshev, patch by Paul Ganssle.

* bpo-6700: Fix inspect.getsourcelines for module level
  frames/tracebacks. Patch by Vladimir Matveev.

* bpo-34171: Running the "trace" module no longer creates the
  "trace.cover" file.

* bpo-34441: Fix crash when an "ABC"-derived class with invalid
  "__subclasses__" is passed as the second argument to "issubclass()".
  Patch by Alexey Izbyshev.

* bpo-34427: Fix infinite loop in "a.extend(a)" for "MutableSequence"
  subclasses.

* bpo-34412: Make "signal.strsignal()" work on HP-UX. Patch by Michael
  Osipov.

* bpo-20849: shutil.copytree now accepts a new "dirs_exist_ok" keyword
  argument. Patch by Josh Bronson.

* bpo-31715: Associate ".mjs" file extension with
  "application/javascript" MIME Type.

* bpo-34384: "os.readlink()" now accepts *path-like* and "bytes"
  objects on Windows.

* bpo-22602: The UTF-7 decoder now raises "UnicodeDecodeError" for
  ill-formed sequences starting with “+” (as specified in RFC 2152).
  Patch by Zackery Spytz.

* bpo-2122: The "mmap.flush()" method now returns "None" on success,
  raises an exception on error under all platforms.

* bpo-34341: Appending to the ZIP archive with the ZIP64 extension no
  longer grows the size of extra fields of existing entries.

* bpo-34333: Fix %-formatting in "pathlib.PurePath.with_suffix()" when
  formatting an error message.

* bpo-18540: The "imaplib.IMAP4" and "imaplib.IMAP4_SSL" classes now
  resolve to the local host IP correctly when the default value of
  *host* parameter ("''") is used.

* bpo-26502: Implement "traceback.FrameSummary.__len__()" method to
  preserve compatibility with the old tuple API.

* bpo-34318: "assertRaises()", "assertRaisesRegex()", "assertWarns()"
  and "assertWarnsRegex()" no longer success if the passed callable is
  None. They no longer ignore unknown keyword arguments in the context
  manager mode. A DeprecationWarning was raised in these cases since
  Python 3.5.

* bpo-9372: Deprecate "__getitem__()" methods of
  "xml.dom.pulldom.DOMEventStream", "wsgiref.util.FileWrapper" and
  "fileinput.FileInput".

* bpo-33613: Fix a race condition in
  "multiprocessing.semaphore_tracker" when the tracker receives SIGINT
  before it can register signal handlers for ignoring it.

* bpo-34248: Report filename in the exception raised when the database
  file cannot be opened by "dbm.gnu.open()" and "dbm.ndbm.open()" due
  to OS-related error. Patch by Zsolt Cserna.

* bpo-33089: Add math.dist() to compute the Euclidean distance between
  two points.

* bpo-34246: "smtplib.SMTP.send_message()" no longer modifies the
  content of the *mail_options* argument. Patch by Pablo S. Blum de
  Aguiar.

* bpo-31047: Fix "ntpath.abspath" for invalid paths on windows. Patch
  by Franz Woellert.

* bpo-32321: Add pure Python fallback for functools.reduce. Patch by
  Robert Wright.

* bpo-34270: The default asyncio task class now always has a name
  which can be get or set using two new methods ("get_name()" and
  "set_name()") and is visible in the "repr()" output. An initial name
  can also be set using the new "name" keyword argument to
  "asyncio.create_task()" or the "create_task()" method of the event
  loop. If no initial name is set, the default Task implementation
  generates a name like "Task-1" using a monotonic counter.

* bpo-34263: asyncio’s event loop will not pass timeouts longer than
  one day to epoll/select etc.

* bpo-34035: Fix several AttributeError in zipfile seek() methods.
  Patch by Mickaël Schoentgen.

* bpo-32215: Fix performance regression in "sqlite3" when a DML
  statement appeared in a different line than the rest of the SQL
  query.

* bpo-34075: Deprecate passing non-ThreadPoolExecutor instances to
  "AbstractEventLoop.set_default_executor()".

* bpo-34251: Restore "msilib.Win64" to preserve backwards
  compatibility since it’s already used by "distutils"’ "bdist_msi"
  command.

* bpo-19891: Ignore errors caused by missing / non-writable homedir
  while writing history during exit of an interactive session.  Patch
  by Anthony Sottile.

* bpo-33089: Enhanced math.hypot() to support more than two
  dimensions.

* bpo-34228: tracemalloc: PYTHONTRACEMALLOC=0 environment variable and
  -X tracemalloc=0 command line option are now allowed to disable
  explicitly tracemalloc at startup.

* bpo-13041: Use "shutil.get_terminal_size()" to calculate the
  terminal width correctly in the "argparse.HelpFormatter" class.
  Initial patch by Zbyszek Jędrzejewski-Szmek.

* bpo-34213: Allow frozen dataclasses to have a field named “object”.
  Previously this conflicted with an internal use of “object”.

* bpo-34052: "sqlite3.Connection.create_aggregate()",
  "sqlite3.Connection.create_function()",
  "sqlite3.Connection.set_authorizer()",
  "sqlite3.Connection.set_progress_handler()" methods raises TypeError
  when unhashable objects are passed as callable. These methods now
  don’t pass such objects to SQLite API. Previous behavior could lead
  to segfaults. Patch by Sergey Fedoseev.

* bpo-34197: Attributes *skipinitialspace*, *doublequote* and *strict*
  of the *dialect* attribute of the "csv" reader are now "bool"
  instances instead of integers 0 or 1.

* bpo-32788: Errors other than "TypeError" raised in methods
  "__adapt__()" and "__conform__()" in the "sqlite3" module are now
  propagated to the user.

* bpo-21446: The "reload" fixer now uses "importlib.reload()" instead
  of deprecated "imp.reload()".

* bpo-940286: pydoc’s "Helper.showtopic()" method now prints the cross
  references of a topic correctly.

* bpo-34164: "base64.b32decode()" could raise UnboundLocalError or
  OverflowError for incorrect padding.  Now it always raises
  "base64.Error" in these cases.

* bpo-33729: Fixed issues with arguments parsing in "hashlib".

* bpo-34097: ZipFile can zip files older than 1980-01-01 and newer
  than 2107-12-31 using a new "strict_timestamps" parameter at the
  cost of setting the timestamp to the limit.

* bpo-34108: Remove extraneous CR in 2to3 refactor.

* bpo-34070: Make sure to only check if the handle is a tty, when
  opening a file with "buffering=-1".

* bpo-27494: Reverted bpo-27494. 2to3 rejects now a trailing comma in
  generator expressions.

* bpo-33967: functools.singledispatch now raises TypeError instead of
  IndexError when no positional arguments are passed.

* bpo-34041: Add the parameter *deterministic* to the
  "sqlite3.Connection.create_function()" method. Patch by Sergey
  Fedoseev.

* bpo-34056: Ensure the loader shim created by "imp.load_module"
  always returns bytes from its "get_data()" function. This fixes
  using "imp.load_module" with **PEP 552** hash-based pycs.

* bpo-34054: The multiprocessing module now uses the monotonic clock
  "time.monotonic()" instead of the system clock "time.time()" to
  implement timeout.

* bpo-34043: Optimize tarfile uncompress performance about 15% when
  gzip is used.

* bpo-34044: "subprocess.Popen" now copies the *startupinfo* argument
  to leave it unchanged: it will modify the copy, so that the same
  "STARTUPINFO" object can be used multiple times.

* bpo-34010: Fixed a performance regression for reading streams with
  tarfile. The buffered read should use a list, instead of appending
  to a bytes object.

* bpo-34019: webbrowser: Correct the arguments passed to Opera Browser
  when opening a new URL using the "webbrowser" module. Patch by
  Bumsik Kim.

* bpo-34003: csv.DictReader now creates dicts instead of OrderedDicts.
  Patch by Michael Selik.

* bpo-33978: Closed existing logging handlers before reconfiguration
  via fileConfig and dictConfig. Patch by Karthikeyan Singaravelan.

* bpo-14117: Make minor tweaks to turtledemo. The ‘wikipedia’ example
  is now ‘rosette’, describing what it draws.  The ‘penrose’ print
  output is reduced. The’1024’ output of ‘tree’ is eliminated.

* bpo-33974: Fixed passing lists and tuples of strings containing
  special characters """, "\", "{", "}" and "\n" as options to "ttk"
  widgets.

* bpo-27500: Fix getaddrinfo to resolve IPv6 addresses correctly.

* bpo-24567: Improve random.choices() to handle subnormal input
  weights that could occasionally trigger an IndexError.

* bpo-33871: Fixed integer overflow in "os.readv()", "os.writev()",
  "os.preadv()" and "os.pwritev()" and in "os.sendfile()" with
  *headers* or *trailers* arguments (on BSD-based OSes and macOS).

* bpo-25007: Add "copy.copy()" and "copy.deepcopy()" support to zlib
  compressors and decompressors.  Patch by Zackery Spytz.

* bpo-33929: multiprocessing: Fix a race condition in Popen of
  multiprocessing.popen_spawn_win32. The child process now duplicates
  the read end of pipe instead of “stealing” it. Previously, the read
  end of pipe was “stolen” by the child process, but it leaked a
  handle if the child process had been terminated before it could
  steal the handle from the parent process.

* bpo-33899: Tokenize module now implicitly emits a NEWLINE when
  provided with input that does not have a trailing new line.  This
  behavior now matches what the C tokenizer does internally.
  Contributed by Ammar Askar.

* bpo-33897: Added a ‘force’ keyword argument to
  logging.basicConfig().

* bpo-33695: "shutil.copytree()" uses "os.scandir()" function and all
  copy functions depending from it use cached "os.stat()" values. The
  speedup for copying a directory with 8000 files is around +9% on
  Linux, +20% on Windows and + 30% on a Windows SMB share. Also the
  number of "os.stat()" syscalls is reduced by 38% making
  "shutil.copytree()" especially faster on network filesystems.
  (Contributed by Giampaolo Rodola’ in bpo-33695.)

* bpo-33916: bz2 and lzma: When Decompressor.__init__() is called
  twice, free the old lock to not leak memory.

* bpo-32568: Make select.epoll() and its documentation consistent
  regarding *sizehint* and *flags*.

* bpo-33833: Fixed bug in asyncio where ProactorSocketTransport logs
  AssertionError if force closed during write.

* bpo-33663: Convert content length to string before putting to
  header.

* bpo-33721: "os.path" functions that return a boolean result like
  "exists()", "lexists()", "isdir()", "isfile()", "islink()", and
  "ismount()", and "pathlib.Path" methods that return a boolean result
  like "exists()", "is_dir()", "is_file()", "is_mount()",
  "is_symlink()", "is_block_device()", "is_char_device()",
  "is_fifo()", "is_socket()" now return "False" instead of raising
  "ValueError" or its subclasses "UnicodeEncodeError" and
  "UnicodeDecodeError" for paths that contain characters or bytes
  unrepresentable at the OS level.

* bpo-26544: Fixed implementation of "platform.libc_ver()". It almost
  always returned version ‘2.9’ for glibc.

* bpo-33843: Remove deprecated "cgi.escape", "cgi.parse_qs" and
  "cgi.parse_qsl".

* bpo-33842: Remove "tarfile.filemode" which is deprecated since
  Python 3.3.

* bpo-30167: Prevent site.main() exception if PYTHONSTARTUP is set.
  Patch by Steve Weber.

* bpo-33805: Improve error message of dataclasses.replace() when an
  InitVar is not specified

* bpo-33687: Fix the call to "os.chmod()" for "uu.decode()" if a mode
  is given or decoded. Patch by Timo Furrer.

* bpo-33812: Datetime instance d with non-None tzinfo, but with
  d.tzinfo.utcoffset(d) returning None is now treated as naive by the
  astimezone() method.

* bpo-32108: In configparser, don’t clear section when it is assigned
  to itself.

* bpo-27397: Make email module properly handle invalid-length base64
  strings.

* bpo-33578: Implement multibyte encoder/decoder state methods

* bpo-30805: Avoid race condition with debug logging

* bpo-33476: Fix _header_value_parser.py when address group is missing
  final ‘;’. Contributed by Enrique Perez-Terron

* bpo-33694: asyncio: Fix a race condition causing data loss on
  pause_reading()/resume_reading() when using the ProactorEventLoop.

* bpo-32493: Correct test for "uuid_enc_be" availability in
  "configure.ac". Patch by Michael Felt.

* bpo-33792: Add asyncio.WindowsSelectorEventLoopPolicy and
  asyncio.WindowsProactorEventLoopPolicy.

* bpo-33274: W3C DOM Level 1 specifies return value of
  Element.removeAttributeNode() as “The Attr node that was removed.”
  xml.dom.minidom now complies with this requirement.

* bpo-33778: Update "unicodedata"’s database to Unicode version
  11.0.0.

* bpo-33165: Added a stacklevel parameter to logging calls to allow
  use of wrapper/helper functions for logging APIs.

* bpo-33770: improve base64 exception message for encoded inputs of
  invalid length

* bpo-33769: asyncio/start_tls: Fix error message; cancel callbacks in
  case of an unhandled error; mark SSLTransport as closed if it is
  aborted.

* bpo-33767: The concatenation ("+") and repetition ("*") sequence
  operations now raise "TypeError" instead of "SystemError" when
  performed on "mmap.mmap" objects.  Patch by Zackery Spytz.

* bpo-33734: asyncio/ssl: Fix AttributeError, increase default
  handshake timeout

* bpo-31014: Fixed creating a controller for "webbrowser" when a user
  specifies a path to an entry in the BROWSER environment variable.
  Based on patch by John Still.

* bpo-2504: Add gettext.pgettext() and variants.

* bpo-33197: Add description property for _ParameterKind

* bpo-32751: When cancelling the task due to a timeout,
  "asyncio.wait_for()" will now wait until the cancellation is
  complete.

* bpo-32684: Fix gather to propagate cancellation of itself even with
  return_exceptions.

* bpo-33654: Support protocol type switching in
  SSLTransport.set_protocol().

* bpo-33674: Pause the transport as early as possible to further
  reduce the risk of data_received() being called before
  connection_made().

* bpo-33671: "shutil.copyfile()", "shutil.copy()", "shutil.copy2()",
  "shutil.copytree()" and "shutil.move()" use platform-specific fast-
  copy syscalls on Linux and macOS in order to copy the file more
  efficiently. On Windows "shutil.copyfile()" uses a bigger default
  buffer size (1 MiB instead of 16 KiB) and a "memoryview()"-based
  variant of "shutil.copyfileobj()" is used. The speedup for copying a
  512MiB file is about +26% on Linux, +50% on macOS and +40% on
  Windows. Also, much less CPU cycles are consumed. (Contributed by
  Giampaolo Rodola’ in bpo-25427.)

* bpo-33674: Fix a race condition in SSLProtocol.connection_made() of
  asyncio.sslproto: start immediately the handshake instead of using
  call_soon(). Previously, data_received() could be called before the
  handshake started, causing the handshake to hang or fail.

* bpo-31647: Fixed bug where calling write_eof() on a
  _SelectorSocketTransport after it’s already closed raises
  AttributeError.

* bpo-32610: Make asyncio.all_tasks() return only pending tasks.

* bpo-32410: Avoid blocking on file IO in sendfile fallback code

* bpo-33469: Fix RuntimeError after closing loop that used
  run_in_executor

* bpo-33672: Fix Task.__repr__ crash with Cython’s bogus coroutines

* bpo-33654: Fix transport.set_protocol() to support switching between
  asyncio.Protocol and asyncio.BufferedProtocol.  Fix loop.start_tls()
  to work with asyncio.BufferedProtocols.

* bpo-33652: Pickles of type variables and subscripted generics are
  now future-proof and compatible with older Python versions.

* bpo-32493: Fixed "uuid.uuid1()" on FreeBSD.

* bpo-33238: Add "InvalidStateError" to "concurrent.futures".
  "Future.set_result" and "Future.set_exception" now raise
  "InvalidStateError" if the futures are not pending or running. Patch
  by Jason Haydaman.

* bpo-33618: Finalize and document preliminary and experimental TLS
  1.3 support with OpenSSL 1.1.1

* bpo-33625: Release GIL on "grp.getgrnam", "grp.getgrgid",
  "pwd.getpwnam" and "pwd.getpwuid" if reentrant variants of these
  functions are available. Patch by William Grzybowski.

* bpo-33623: Fix possible SIGSGV when asyncio.Future is created in
  __del__

* bpo-11874: Use a better regex when breaking usage into wrappable
  parts. Avoids bogus assertion errors from custom metavar strings.

* bpo-30877: Fixed a bug in the Python implementation of the JSON
  decoder that prevented the cache of parsed strings from clearing
  after finishing the decoding. Based on patch by c-fos.

* bpo-33604: Remove HMAC default to md5 marked for removal in 3.8
  (removal originally planned in 3.6, bump to 3.8 in PR 7062).

* bpo-33582: Emit a deprecation warning for inspect.formatargspec

* bpo-21145: Add "functools.cached_property" decorator, for computed
  properties cached for the life of the instance.

* bpo-33570: Change TLS 1.3 cipher suite settings for compatibility
  with OpenSSL 1.1.1-pre6 and newer. OpenSSL 1.1.1 will have TLS 1.3
  ciphers enabled by default.

* bpo-28556: Do not simplify arguments to "typing.Union". Now
  "Union[Manager, Employee]" is not simplified to "Employee" at
  runtime. Such simplification previously caused several bugs and
  limited possibilities for introspection.

* bpo-12486: "tokenize.generate_tokens()" is now documented as a
  public API to tokenize unicode strings. It was previously present
  but undocumented.

* bpo-33540: Add a new "block_on_close" class attribute to
  "ForkingMixIn" and "ThreadingMixIn" classes of "socketserver".

* bpo-33548: tempfile._candidate_tempdir_list should consider common
  TEMP locations

* bpo-33109: argparse subparsers are once again not required by
  default, reverting the change in behavior introduced by bpo-26510 in
  3.7.0a2.

* bpo-33541: Remove unused private method "_strptime.LocaleTime.__pad"
  (a.k.a. "_LocaleTime__pad").

* bpo-33536: dataclasses.make_dataclass now checks for invalid field
  names and duplicate fields. Also, added a check for invalid field
  specifications.

* bpo-33542: Prevent "uuid.get_node" from using a DUID instead of a
  MAC on Windows. Patch by Zvi Effron

* bpo-26819: Fix race condition with "ReadTransport.resume_reading" in
  Windows proactor event loop.

* Fix failure in "typing.get_type_hints()" when ClassVar was provided
  as a string forward reference.

* bpo-33516: "unittest.mock.MagicMock" now supports the "__round__"
  magic method.

* bpo-28612: Added support for Site Maps to urllib’s "RobotFileParser"
  as "RobotFileParser.site_maps()". Patch by Lady Red, based on patch
  by Peter Wirtz.

* bpo-28167: Remove platform.linux_distribution, which was deprecated
  since 3.5.

* bpo-33504: Switch the default dictionary implementation for
  "configparser" from "collections.OrderedDict" to the standard "dict"
  type.

* bpo-33505: Optimize asyncio.ensure_future() by reordering if checks:
  1.17x faster.

* bpo-33497: Add errors param to cgi.parse_multipart and make an
  encoding in FieldStorage use the given errors (needed for Twisted).
  Patch by Amber Brown.

* bpo-29235: The "cProfile.Profile" class can now be used as a context
  manager. Patch by Scott Sanderson.

* bpo-33495: Change dataclasses.Fields repr to use the repr of each of
  its members, instead of str.  This makes it more clear what each
  field actually represents.  This is especially true for the ‘type’
  member.

* bpo-26103: Correct "inspect.isdatadescriptor" to look for "__set__"
  or "__delete__".  Patch by Aaron Hall.

* bpo-29209: Removed the "doctype()" method and the *html* parameter
  of the constructor of "XMLParser".  The "doctype()" method defined
  in a subclass will no longer be called. Deprecated methods
  "getchildren()" and "getiterator()" in the "ElementTree" module emit
  now a "DeprecationWarning" instead of "PendingDeprecationWarning".

* bpo-33453: Fix dataclasses to work if using literal string type
  annotations or if using PEP 563 “Postponed Evaluation of
  Annotations”. Only specific string prefixes are detected for both
  ClassVar (“ClassVar” and “typing.ClassVar”) and InitVar (“InitVar”
  and “dataclasses.InitVar”).

* bpo-28556: Minor fixes in typing module: add annotations to
  "NamedTuple.__new__", pass "*args" and "**kwds" in
  "Generic.__new__".  Original PRs by Paulius Šarka and Chad Dombrova.

* bpo-33365: Print the header values besides the header keys instead
  just the header keys if *debuglevel* is set to >0 in "http.client".
  Patch by Marco Strigl.

* bpo-20087: Updated alias mapping with glibc 2.27 supported locales.

* bpo-33422: Fix trailing quotation marks getting deleted when looking
  up byte/string literals on pydoc. Patch by Andrés Delfino.

* bpo-28167: The function "platform.linux_distribution" and
  "platform.dist" now trigger a "DeprecationWarning" and have been
  marked for removal in Python 3.8

* bpo-33281: Fix ctypes.util.find_library regression on macOS.

* bpo-33311: Text and html output generated by cgitb does not display
  parentheses if the current call is done directly in the module.
  Patch by Stéphane Blondon.

* bpo-27300: The file classes in *tempfile* now accept an *errors*
  parameter that complements the already existing *encoding*.  Patch
  by Stephan Hohe.

* bpo-32933: "unittest.mock.mock_open()" now supports iteration over
  the file contents. Patch by Tony Flury.

* bpo-33217: Raise "TypeError" when looking up non-Enum objects in
  Enum classes and Enum members.

* bpo-33197: Update error message when constructing invalid
  inspect.Parameters Patch by Dong-hee Na.

* bpo-33383: Fixed crash in the get() method of the "dbm.ndbm"
  database object when it is called with a single argument.

* bpo-33375: The warnings module now finds the Python file associated
  with a warning from the code object, rather than the frame’s global
  namespace. This is consistent with how tracebacks and pdb find
  filenames, and should work better for dynamically executed code.

* bpo-33336: "imaplib" now allows "MOVE" command in "IMAP4.uid()" (RFC
  6851: IMAP MOVE Extension) and potentially as a name of supported
  method of "IMAP4" object.

* bpo-32455: Added *jump* parameter to "dis.stack_effect()".

* bpo-27485: Rename and deprecate undocumented functions in
  "urllib.parse()".

* bpo-33332: Add "signal.valid_signals()" to expose the POSIX
  sigfillset() functionality.

* bpo-33251: "ConfigParser.items()" was fixed so that key-value pairs
  passed in via "vars" are not included in the resulting output.

* bpo-33329: Fix multiprocessing regression on newer glibcs

* bpo-33334: "dis.stack_effect()" now supports all defined opcodes
  including NOP and EXTENDED_ARG.

* bpo-991266: Fix quoting of the "Comment" attribute of
  "http.cookies.SimpleCookie".

* bpo-33131: Upgrade bundled version of pip to 10.0.1.

* bpo-33308: Fixed a crash in the "parser" module when converting an
  ST object to a tree of tuples or lists with "line_info=False" and
  "col_info=True".

* bpo-23403: lib2to3 now uses pickle protocol 4 for pre-computed
  grammars.

* bpo-33266: lib2to3 now recognizes "rf'...'" strings.

* bpo-11594: Ensure line-endings are respected when using lib2to3.

* bpo-33254: Have "importlib.resources.contents()" and
  "importlib.abc.ResourceReader.contents()" return an *iterable*
  instead of an *iterator*.

* bpo-33265: "contextlib.ExitStack" and "contextlib.AsyncExitStack"
  now use a method instead of a wrapper function for exit callbacks.

* bpo-33263: Fix FD leak in "_SelectorSocketTransport"  Patch by Vlad
  Starostin.

* bpo-33256: Fix display of "<module>" call in the html produced by
  "cgitb.html()". Patch by Stéphane Blondon.

* bpo-33144: "random.Random()" and its subclassing mechanism got
  optimized to check only once at class/subclass instantiation time
  whether its "getrandbits()" method can be relied on by other
  methods, including "randrange()", for the generation of arbitrarily
  large random integers. Patch by Wolfgang Maier.

* bpo-33185: Fixed regression when running pydoc with the "-m" switch.
  (The regression was introduced in 3.7.0b3 by the resolution of
  bpo-33053)

  This fix also changed pydoc to add "os.getcwd()" to "sys.path" when
  necessary, rather than adding ""."".

* bpo-29613: Added support for the "SameSite" cookie flag to the
  "http.cookies" module.

* bpo-33169: Delete entries of "None" in "sys.path_importer_cache"
  when "importlib.machinery.invalidate_caches()" is called.

* bpo-33203: "random.Random.choice()" now raises "IndexError" for
  empty sequences consistently even when called from subclasses
  without a "getrandbits()" implementation.

* bpo-33224: Update difflib.mdiff() for **PEP 479**.  Convert an
  uncaught StopIteration in a generator into a return-statement.

* bpo-33209: End framing at the end of C implementation of
  "pickle.Pickler.dump()".

* bpo-32861: The urllib.robotparser’s "__str__" representation now
  includes wildcard entries and the “Crawl-delay” and “Request-rate”
  fields. Also removes extra newlines that were being appended to the
  end of the string. Patch by Michael Lazar.

* bpo-23403: "DEFAULT_PROTOCOL" in "pickle" was bumped to 4. Protocol
  4 is described in **PEP 3154** and available since Python 3.4. It
  offers better performance and smaller size compared to protocol 3
  introduced in Python 3.0.

* bpo-20104: Improved error handling and fixed a reference leak in
  "os.posix_spawn()".

* bpo-33106: Deleting a key from a read-only dbm database raises
  module specific error instead of KeyError.

* bpo-33175: In dataclasses, Field.__set_name__ now looks up the
  __set_name__ special method on the class, not the instance, of the
  default value.

* bpo-32380: Create functools.singledispatchmethod to support generic
  single dispatch on descriptors and methods.

* bpo-33141: Have Field objects pass through __set_name__ to their
  default values, if they have their own __set_name__.

* bpo-33096: Allow ttk.Treeview.insert to insert iid that has a false
  boolean value. Note iid=0 and iid=False would be same. Patch by
  Garvit Khatri.

* bpo-32873: Treat type variables and special typing forms as
  immutable by copy and pickle.  This fixes several minor issues and
  inconsistencies, and improves backwards compatibility with Python
  3.6.

* bpo-33134: When computing dataclass’s __hash__, use the lookup table
  to contain the function which returns the __hash__ value.  This is
  an improvement over looking up a string, and then testing that
  string to see what to do.

* bpo-33127: The ssl module now compiles with LibreSSL 2.7.1.

* bpo-32505: Raise TypeError if a member variable of a dataclass is of
  type Field, but doesn’t have a type annotation.

* bpo-33078: Fix the failure on OSX caused by the tests relying on
  sem_getvalue

* bpo-33116: Add ‘Field’ to dataclasses.__all__.

* bpo-32896: Fix an error where subclassing a dataclass with a field
  that uses a default_factory would generate an incorrect class.

* bpo-33100: Dataclasses: If a field has a default value that’s a
  MemberDescriptorType, then it’s from that field being in __slots__,
  not an actual default value.

* bpo-32953: If a non-dataclass inherits from a frozen dataclass,
  allow attributes to be added to the derived class.  Only attributes
  from the frozen dataclass cannot be assigned to.  Require all
  dataclasses in a hierarchy to be either all frozen or all non-
  frozen.

* bpo-33097: Raise RuntimeError when "executor.submit" is called
  during interpreter shutdown.

* bpo-32968: Modulo and floor division involving Fraction and float
  should return float.

* bpo-33061: Add missing "NoReturn" to "__all__" in typing.py

* bpo-33078: Fix the size handling in multiprocessing.Queue when a
  pickling error occurs.

* bpo-33064: lib2to3 now properly supports trailing commas after
  "*args" and "**kwargs" in function signatures.

* bpo-33056: FIX properly close leaking fds in
  concurrent.futures.ProcessPoolExecutor.

* bpo-33021: Release the GIL during fstat() calls, avoiding hang of
  all threads when calling mmap.mmap(), os.urandom(), and
  random.seed().  Patch by Nir Soffer.

* bpo-31804: Avoid failing in multiprocessing.Process if the standard
  streams are closed or None at exit.

* bpo-33034: Providing an explicit error message when casting the port
  property to anything that is not an integer value using "urlparse()"
  and "urlsplit()". Patch by Matt Eaton.

* bpo-30249: Improve struct.unpack_from() exception messages for
  problems with the buffer size and offset.

* bpo-33037: Skip sending/receiving data after SSL transport closing.

* bpo-27683: Fix a regression in "ipaddress" that result of "hosts()"
  is empty when the network is constructed by a tuple containing an
  integer mask and only 1 bit left for addresses.

* bpo-22674: Add the strsignal() function in the signal module that
  returns the system description of the given signal, as returned by
  strsignal(3).

* bpo-32999: Fix C implementation of "ABC.__subclasscheck__(cls,
  subclass)" crashed when "subclass" is not a type object.

* bpo-33009: Fix inspect.signature() for single-parameter
  partialmethods.

* bpo-32969: Expose several missing constants in zlib and fix
  corresponding documentation.

* bpo-32056: Improved exceptions raised for invalid number of channels
  and sample width when read an audio file in modules "aifc", "wave"
  and "sunau".

* bpo-32970: Improved disassembly of the MAKE_FUNCTION instruction.

* bpo-32844: Fix wrong redirection of a low descriptor (0 or 1) to
  stderr in subprocess if another low descriptor is closed.

* bpo-32960: For dataclasses, disallow inheriting frozen from non-
  frozen classes, and also disallow inheriting non-frozen from frozen
  classes. This restriction will be relaxed at a future date.

* bpo-32713: Fixed tarfile.itn handling of out-of-bounds float values.
  Patch by Joffrey Fuhrer.

* bpo-32257: The ssl module now contains OP_NO_RENEGOTIATION constant,
  available with OpenSSL 1.1.0h or 1.1.1.

* bpo-32951: Direct instantiation of SSLSocket and SSLObject objects
  is now prohibited. The constructors were never documented, tested,
  or designed as public constructors. Users were suppose to use
  ssl.wrap_socket() or SSLContext.

* bpo-32929: Remove the tri-state parameter “hash”, and add the
  boolean “unsafe_hash”. If unsafe_hash is True, add a __hash__
  function, but if a __hash__ exists, raise TypeError.  If unsafe_hash
  is False, add a __hash__ based on the values of eq= and frozen=.
  The unsafe_hash=False behavior is the same as the old hash=None
  behavior.  unsafe_hash=False is the default, just as hash=None used
  to be.

* bpo-32947: Add OP_ENABLE_MIDDLEBOX_COMPAT and test workaround for
  TLSv1.3 for future compatibility with OpenSSL 1.1.1.

* bpo-32146: Document the interaction between frozen executables and
  the spawn and forkserver start methods in multiprocessing.

* bpo-30622: The ssl module now detects missing NPN support in
  LibreSSL.

* bpo-32922: dbm.open() now encodes filename with the filesystem
  encoding rather than default encoding.

* bpo-32759: Free unused arenas in multiprocessing.heap.

* bpo-32859: In "os.dup2", don’t check every call whether the "dup3"
  syscall exists or not.

* bpo-32556: nt._getfinalpathname, nt._getvolumepathname and
  nt._getdiskusage now correctly convert from bytes.

* bpo-21060: Rewrite confusing message from setup.py upload from “No
  dist file created in earlier command” to the more helpful “Must
  create and upload files in one command”.

* bpo-32857: In "tkinter", "after_cancel(None)" now raises a
  "ValueError" instead of canceling the first scheduled function.
  Patch by Cheryl Sabella.

* bpo-32852: Make sure sys.argv remains as a list when running trace.

* bpo-31333: "_abc" module is added.  It is a speedup module with C
  implementations for various functions and methods in "abc".
  Creating an ABC subclass and calling "isinstance" or "issubclass"
  with an ABC subclass are up to 1.5x faster. In addition, this makes
  Python start-up up to 10% faster.

  Note that the new implementation hides internal registry and caches,
  previously accessible via private attributes "_abc_registry",
  "_abc_cache", and "_abc_negative_cache".  There are three debugging
  helper methods that can be used instead "_dump_registry",
  "_abc_registry_clear", and "_abc_caches_clear".

* bpo-32841: Fixed "asyncio.Condition" issue which silently ignored
  cancellation after notifying and cancelling a conditional lock.
  Patch by Bar Harel.

* bpo-32819: ssl.match_hostname() has been simplified and no longer
  depends on re and ipaddress module for wildcard and IP addresses.
  Error reporting for invalid wildcards has been improved.

* bpo-19675: "multiprocessing.Pool" no longer leaks processes if its
  initialization fails.

* bpo-32394: socket: Remove
  TCP_FASTOPEN,TCP_KEEPCNT,TCP_KEEPIDLE,TCP_KEEPINTVL flags on older
  version Windows during run-time.

* bpo-31787: Fixed refleaks of "__init__()" methods in various
  modules. (Contributed by Oren Milman)

* bpo-30157: Fixed guessing quote and delimiter in csv.Sniffer.sniff()
  when only the last field is quoted.  Patch by Jake Davis.

* bpo-30688: Added support of "\N{name}" escapes in regular
  expressions. Based on patch by Jonathan Eunice.

* bpo-32792: collections.ChainMap() preserves the order of the
  underlying mappings.

* bpo-32775: "fnmatch.translate()" no longer produces patterns which
  contain set operations. Sets starting with ‘[’ or containing ‘–’,
  ‘&&’, ‘~~’ or ‘||’ will be interpreted differently in regular
  expressions in future versions. Currently they emit warnings.
  fnmatch.translate() now avoids producing patterns containing such
  sets by accident.

* bpo-32622: Implement native fast sendfile for Windows proactor event
  loop.

* bpo-32777: Fix a rare but potential pre-exec child process deadlock
  in subprocess on POSIX systems when marking file descriptors
  inheritable on exec in the child process.  This bug appears to have
  been introduced in 3.4.

* bpo-32647: The ctypes module used to depend on indirect linking for
  dlopen. The shared extension is now explicitly linked against libdl
  on platforms with dl.

* bpo-32749: A "dbm.dumb" database opened with flags ‘r’ is now read-
  only. "dbm.dumb.open()" with flags ‘r’ and ‘w’ no longer creates a
  database if it does not exist.

* bpo-32741: Implement "asyncio.TimerHandle.when()" method.

* bpo-32691: Use mod_spec.parent when running modules with pdb

* bpo-32734: Fixed "asyncio.Lock()" safety issue which allowed
  acquiring and locking the same lock multiple times, without it being
  free. Patch by Bar Harel.

* bpo-32727: Do not include name field in SMTP envelope from address.
  Patch by Stéphane Wirtel

* bpo-31453: Add TLSVersion constants and SSLContext.maximum_version /
  minimum_version attributes. The new API wraps OpenSSL 1.1 https://w
  ww.openssl.org/docs/man1.1.0/ssl/SSL_CTX_set_min_proto_version.html
  feature.

* bpo-24334: Internal implementation details of ssl module were
  cleaned up. The SSLSocket has one less layer of indirection. Owner
  and session information are now handled by the SSLSocket and
  SSLObject constructor. Channel binding implementation has been
  simplified.

* bpo-31848: Fix the error handling in Aifc_read.initfp() when the
  SSND chunk is not found. Patch by Zackery Spytz.

* bpo-32585: Add Ttk spinbox widget to "tkinter.ttk".  Patch by Alan D
  Moore.

* bpo-32512: "profile" CLI accepts "-m module_name" as an alternative
  to script path.

* bpo-8525: help() on a type now displays builtin subclasses. This is
  intended primarily to help with notification of more specific
  exception subclasses.

  Patch by Sanyam Khurana.

* bpo-31639: http.server now exposes a ThreadingHTTPServer class and
  uses it when the module is run with "-m" to cope with web browsers
  pre-opening sockets.

* bpo-29877: compileall: import ProcessPoolExecutor only when needed,
  preventing hangs on low resource platforms

* bpo-32221: Various functions returning tuple containing IPv6
  addresses now omit "%scope" part since the same information is
  already encoded in *scopeid* tuple item. Especially this speeds up
  "socket.recvfrom()" when it receives multicast packet since useless
  resolving of network interface name is omitted.

* bpo-32147: "binascii.unhexlify()" is now up to 2 times faster. Patch
  by Sergey Fedoseev.

* bpo-30693: The TarFile class now recurses directories in a
  reproducible way.

* bpo-30693: The ZipFile class now recurses directories in a
  reproducible way.

* bpo-31680: Added "curses.ncurses_version".

* bpo-31908: Fix output of cover files for "trace" module command-line
  tool. Previously emitted cover files only when "--missing" option
  was used. Patch by Michael Selik.

* bpo-31608: Raise a "TypeError" instead of crashing if a
  "collections.deque" subclass returns a non-deque from "__new__".
  Patch by Oren Milman.

* bpo-31425: Add support for sockets of the AF_QIPCRTR address family,
  supported by the Linux kernel. This is used to communicate with
  services, such as GPS or radio, running on Qualcomm devices. Patch
  by Bjorn Andersson.

* bpo-22005: Implemented unpickling instances of "datetime", "date"
  and "time" pickled by Python 2. "encoding='latin1'" should be used
  for successful decoding.

* bpo-27645: "sqlite3.Connection" now exposes a "backup" method, if
  the underlying SQLite library is at version 3.6.11 or higher.  Patch
  by Lele Gaifax.

* bpo-16865: Support arrays >=2GiB in "ctypes".  Patch by Segev Finer.

* bpo-31508: Removed support of arguments in
  "tkinter.ttk.Treeview.selection". It was deprecated in 3.6.  Use
  specialized methods like "selection_set" for changing the selection.

* bpo-29456: Fix bugs in hangul normalization: u1176, u11a7 and u11c3


Documentation
-------------

* bpo-21257: Document "http.client.parse_headers()".

* bpo-34764: Improve example of iter() with 2nd sentinel argument.

* bpo-35564: Explicitly set master_doc variable in conf.py for
  compliance with Sphinx 2.0

* bpo-35511: Specified that profile.Profile class doesn’t not support
  enable or disable methods. Also, elaborated that Profile object as a
  context manager is only supported in cProfile module.

* bpo-10536: Enhance the gettext docs. Patch by Éric Araujo

* bpo-35089: Remove mention of "typing.io" and "typing.re". Their
  types should be imported from "typing" directly.

* bpo-35038: Fix the documentation about an unexisting "f_restricted"
  attribute in the frame object. Patch by Stéphane Wirtel

* bpo-35042: Replace PEP XYZ by the pep role and allow to use the
  direct links to the PEPs.

* bpo-35044: Fix the documentation with the role "exc" for the
  appropriated exception. Patch by Stéphane Wirtel

* bpo-35035: Rename documentation for "email.utils" to
  "email.utils.rst".

* bpo-34967: Use app.add_object_type() instead of the deprecated
  Sphinx function app.description_unit()

* bpo-34913: Add documentation about the new command line interface of
  the gzip module.

* bpo-32174: chm document displays non-ASCII charaters properly on
  some MBCS Windows systems.

* bpo-11233: Create availability directive for documentation.
  Original patch by Georg Brandl.

* bpo-34790: Document how passing coroutines to asyncio.wait() can be
  confusing.

* bpo-34552: Make clear that "==" operator sometimes is equivalent to
  "is". The "<", "<=", ">" and ">=" operators are only defined where
  they make sense.

* bpo-28617: Fixed info in the stdtypes docs concerning the types that
  support membership tests.

* bpo-20177: Migrate datetime.date.fromtimestamp to Argument Clinic.
  Patch by Tim Hoffmann.

* bpo-34065: Fix wrongly written basicConfig documentation markup
  syntax

* bpo-33460: replaced ellipsis with correct error codes in tutorial
  chapter 3.

* bpo-33847: Add ‘@’ operator entry to index.

* bpo-33409: Clarified the relationship between **PEP 538**’s
  PYTHONCOERCECLOCALE and PEP 540’s PYTHONUTF8 mode.

* bpo-33197: Add versionadded tag to the documentation of
  ParameterKind.description

* bpo-17045: Improve the C-API doc for PyTypeObject.  This includes
  adding several quick-reference tables and a lot of missing
  slot/typedef entries. The existing entries were also cleaned up with
  a slightly more consistent format.

* bpo-33736: Improve the documentation of "asyncio.open_connection()",
  "asyncio.start_server()" and their UNIX socket counterparts.

* bpo-23859: Document that "asyncio.wait()" does not cancel its
  futures on timeout.

* bpo-32436: Document **PEP 567** changes to asyncio.

* bpo-33604: Update HMAC md5 default to a DeprecationWarning, bump
  removal to 3.8.

* bpo-33594: Document "getargspec", "from_function" and "from_builtin"
  as deprecated in their respective docstring, and include version
  since deprecation in DeprecationWarning message.

* bpo-33503: Fix broken pypi link

* bpo-33421: Add missing documentation for
  "typing.AsyncContextManager".

* bpo-33487: BZ2file now emit a DeprecationWarning when buffering=None
  is passed, the deprecation message and documentation also now
  explicitly state it is deprecated since 3.0.

* bpo-33378: Add Korean language switcher for
  https://docs.python.org/3/

* bpo-33276: Clarify that the "__path__" attribute on modules cannot
  be just any value.

* bpo-33201: Modernize documentation for writing C extension types.

* bpo-33195: Deprecate "Py_UNICODE" usage in "c-api/arg" document.
  "Py_UNICODE" related APIs are deprecated since Python 3.3, but it is
  missed in the document.

* bpo-33126: Document PyBuffer_ToContiguous().

* bpo-27212: Modify documentation for the "islice()" recipe to consume
  initial values up to the start index.

* bpo-28247: Update "zipapp" documentation to describe how to make
  standalone applications.

* bpo-18802: Documentation changes for ipaddress.  Patch by Jon Foster
  and Berker Peksag.

* bpo-27428: Update documentation to clarify that
  "WindowsRegistryFinder" implements "MetaPathFinder". (Patch by
  Himanshu Lakhara)

* bpo-28124: The ssl module function ssl.wrap_socket() has been de-
  emphasized and deprecated in favor of the more secure and efficient
  SSLContext.wrap_socket() method.

* bpo-17232: Clarify docs for -O and -OO.  Patch by Terry Reedy.

* bpo-32436: Add documentation for the contextvars module (PEP 567).

* bpo-32800: Update link to w3c doc for xml default namespaces.

* bpo-11015: Update "test.support" documentation.

* bpo-32613: Update the faq/windows.html to use the py command from
  PEP 397 instead of python.

* bpo-8722: Document "__getattr__()" behavior when property "get()"
  method raises "AttributeError".

* bpo-32614: Modify RE examples in documentation to use raw strings to
  prevent "DeprecationWarning" and add text to REGEX HOWTO to
  highlight the deprecation.

* bpo-20709: Remove the paragraph where we explain that os.utime()
  does not support a directory as path under Windows. Patch by Jan-
  Philip Gehrcke

* bpo-32722: Remove the bad example in the tutorial of the Generator
  Expression. Patch by Stéphane Wirtel

* bpo-31972: Improve docstrings for "pathlib.PurePath" subclasses.

* bpo-30607: Use the externalized "python-docs-theme" package when
  building the documentation.

* bpo-8243: Add a note about curses.addch and curses.addstr exception
  behavior when writing outside a window, or pad.

* bpo-32337: Update documentation related with "dict" order.

* bpo-25041: Document "AF_PACKET" in the "socket" module.

* bpo-31432: Clarify meaning of CERT_NONE, CERT_OPTIONAL, and
  CERT_REQUIRED flags for ssl.SSLContext.verify_mode.


Tests
-----

* bpo-35772: Fix sparse file tests of test_tarfile on ppc64 with the
  tmpfs filesystem. Fix the function testing if the filesystem
  supports sparse files: create a file which contains data and
  “holes”, instead of creating a file which contains no data. tmpfs
  effective block size is a page size (tmpfs lives in the page cache).
  RHEL uses 64 KiB pages on aarch64, ppc64, ppc64le, only s390x and
  x86_64 use 4 KiB pages, whereas the test punch holes of 4 KiB.

* bpo-35045: Make ssl tests less strict and also accept TLSv1 as
  system default. The changes unbreaks test_min_max_version on Fedora
  29.

* bpo-32710: "test_asyncio/test_sendfile.py" now resets the event loop
  policy using "tearDownModule()" as done in other tests, to prevent a
  warning when running tests on Windows.

* bpo-33717: test.pythoninfo now logs information of all clocks, not
  only time.time() and time.perf_counter().

* bpo-35488: Add a test to pathlib’s Path.match() to verify it does
  not support glob-style ** recursive pattern matching.

* bpo-31731: Fix a race condition in "check_interrupted_write()" of
  test_io: create directly the thread with SIGALRM signal blocked,
  rather than blocking the signal later from the thread. Previously,
  it was possible that the thread gets the signal before the signal is
  blocked.

* bpo-35424: Fix test_multiprocessing_main_handling: use
  "multiprocessing.Pool" with a context manager and then explicitly
  join the pool.

* bpo-35519: Rename "test.bisect" module to "test.bisect_cmd" to avoid
  conflict with "bisect" module when running directly a test like
  "./python Lib/test/test_xmlrpc.py".

* bpo-35513: Replace "time.time()" with "time.monotonic()" in tests to
  measure time delta.

* bpo-34279: "test.support.run_unittest()" no longer raise
  "TestDidNotRun" if the test result contains skipped tests. The
  exception is now only raised if no test have been run and no test
  have been skipped.

* bpo-35412: Add testcase to "test_future4": check unicode literal.

* bpo-26704: Added test demonstrating double-patching of an instance
  method. Patch by Anthony Sottile.

* bpo-33725: test_multiprocessing_fork may crash on recent versions of
  macOS.  Until the issue is resolved, skip the test on macOS.

* bpo-35352: Modify test_asyncio to use the certificate set from the
  test directory.

* bpo-35317: Fix "mktime()" overflow error in "test_email": run
  "test_localtime_daylight_true_dst_true()" and
  "test_localtime_daylight_false_dst_true()" with a specific timezone.

* bpo-21263: After several reports that test_gdb does not work
  properly on macOS and since gdb is not shipped by default anymore,
  test_gdb is now skipped on macOS when LLVM Clang has been used to
  compile Python. Patch by Lysandros Nikolaou

* bpo-34279: regrtest issue a warning when no tests have been executed
  in a particular test file. Also, a new final result state is issued
  if no test have been executed across all test files. Patch by Pablo
  Galindo.

* bpo-34962: make docstest in Doc now passes., and is enforced in CI

* bpo-23596: Use argparse for the command line of the gzip module.
  Patch by Antony Lee

* bpo-34537: Fix "test_gdb.test_strings()" when "LC_ALL=C" and GDB was
  compiled with Python 3.6 or earlier.

* bpo-34587: test_socket: Remove RDSTest.testCongestion(). The test
  tries to fill the receiver’s socket buffer and expects an error. But
  the RDS protocol doesn’t require that. Moreover, the Linux
  implementation of RDS expects that the producer of the messages
  reduces its rate, it’s not the role of the receiver to trigger an
  error. The test fails on Fedora 28 by design, so just remove it.

* bpo-34661: Fix test_shutil if unzip doesn’t support -t.

* bpo-34200: Fixed non-deterministic flakiness of test_pkg by not
  using the scary test.support.module_cleanup() logic to save and
  restore sys.modules contents between test cases.

* bpo-34569: The experimental PEP 554 data channels now correctly pass
  negative PyLong objects between subinterpreters on 32-bit systems.
  Patch by Michael Felt.

* bpo-34594: Fix usage of hardcoded "errno" values in the tests.

* bpo-34579: Fix test_embed for AIX Patch by Michael Felt

* bpo-34542: Use 3072 RSA keys and SHA-256 signature for test certs
  and keys.

* bpo-11193: Remove special condition for AIX in
  "test_subprocess.test_undecodable_env"

* bpo-34347: Fix "test_utf8_mode.test_cmd_line" for AIX

* bpo-34490: On AIX with AF_UNIX family sockets getsockname() does not
  provide ‘sockname’, so skip calls to
  transport.get_extra_info(‘sockname’)

* bpo-34391: Fix ftplib test for TLS 1.3 by reading from data socket.

* bpo-11192: Fix "test_socket" on AIX 6.1 and later IPv6 zone id
  supports only supported by inet_pton6_zone() Switch to runtime-based
  platform.system() to establish current platform  rather than build-
  time based sys.platform()

* bpo-34399: Update all RSA keys and DH params to use at least 2048
  bits.

* bpo-34373: Fix "test_mktime" and "test_pthread_getcpuclickid" tests
  for AIX Add range checking for "_PyTime_localtime" for AIX Patch by
  Michael Felt

* bpo-11191: Skip the distutils test ‘test_search_cpp’ when using XLC
  as compiler patch by aixtools (Michael Felt)

* Improved an error message when mock assert_has_calls fails.

* bpo-33746: Fix test_unittest when run in verbose mode.

* bpo-33901: Fix test_dbm_gnu on macOS with gdbm 1.15: add a larger
  value to make sure that the file size changes.

* bpo-33873: Fix a bug in "regrtest" that caused an extra test to run
  if –huntrleaks/-R was used. Exit with error in case that invalid
  parameters are specified to –huntrleaks/-R (at least one warmup run
  and one repetition must be used).

* bpo-33562: Check that a global asyncio event loop policy is not left
  behind by any tests.

* bpo-33655: Ignore test_posix_fallocate failures on BSD platforms
  that might be due to running on ZFS.

* bpo-32962: Fixed test_gdb when Python is compiled with flags -mcet
  -fcf-protection -O0.

* bpo-33358: Fix "test_embed.test_pre_initialization_sys_options()"
  when the interpreter is built with "--enable-shared".

* bpo-32872: Avoid regrtest compatibility issue with namespace
  packages.

* bpo-32517: Fix failing "test_asyncio" on macOS 10.12.2+ due to
  transport of "KqueueSelector" loop was not being closed.

* bpo-32663: Making sure the "SMTPUTF8SimTests" class of tests gets
  run in test_smtplib.py.

* bpo-27643: Test_C test case needs “signed short” bitfields, but the
  IBM XLC compiler (on AIX) does not support this Skip the code and
  test when AIX and XLC are used

  Applicable to Python2-2.7 and later

* bpo-19417: Add test_bdb.py.

* bpo-31809: Add tests to verify connection with secp ECDH curves.


Build
-----

* bpo-34691: The _contextvars module is now built into the core Python
  library on Windows.

* bpo-35683: Improved Azure Pipelines build steps and now verifying
  layouts correctly

* bpo-35642: Remove asynciomodule.c from pythoncore.vcxproj

* bpo-35550: Fix incorrect Solaris #ifdef checks to look for __sun &&
  __SVR4 instead of sun when compiling.

* bpo-35499: "make profile-opt" no longer replaces "CFLAGS_NODIST"
  with "CFLAGS". It now adds profile-guided optimization (PGO) flags
  to "CFLAGS_NODIST": existing "CFLAGS_NODIST" flags are kept.

* bpo-35257: Avoid leaking the linker flags from Link Time
  Optimizations (LTO) into distutils when compiling C extensions.

* bpo-35351: When building Python with clang and LTO, LTO flags are no
  longer passed into CFLAGS to build third-party C extensions through
  distutils.

* bpo-35139: Fix a compiler error when statically linking "pyexpat" in
  "Modules/Setup".

* bpo-35059: PCbuild: Set InlineFunctionExpansion to
  OnlyExplicitInline (“/Ob1” option) in pyproject.props in Debug mode
  to expand functions marked as inline. This change should make Python
  compiled in Debug mode a little bit faster on Windows.

* bpo-35011: Restores the use of pyexpatns.h to isolate our embedded
  copy of the expat C library so that its symbols do not conflict at
  link or dynamic loading time with an embedding application or other
  extension modules with their own version of libexpat.

* bpo-28015: Have –with-lto works correctly with clang.

* bpo-34765: Update the outdated install-sh file to the latest
  revision from automake v1.16.1

* bpo-34585: Check for floating-point byte order in configure.ac using
  compilation tests instead of executing code, so that these checks
  work in cross-compiled builds.

* bpo-34710: Fixed SSL module build with OpenSSL & pedantic CFLAGS.

* bpo-34582: Add JUnit XML output for regression tests and update
  Azure DevOps builds.

* bpo-34081: Make Sphinx warnings as errors in the Docs Makefile.

* bpo-34555: Fix for case where it was not possible to have both
  "HAVE_LINUX_VM_SOCKETS_H" and "HAVE_SOCKADDR_ALG" be undefined.

* bpo-33015: Fix an undefined behaviour in the pthread implementation
  of "PyThread_start_new_thread()": add a function wrapper to always
  return "NULL".

* bpo-34245: The Python shared library is now installed with write
  permission (mode 0755), which is the standard way of installing such
  libraries.

* bpo-34121: Fix detection of C11 atomic support on clang.

* bpo-32430: Rename Modules/Setup.dist to Modules/Setup, and remove
  the necessity to copy the former manually to the latter when
  updating the local source tree.

* bpo-30345: Add -g to LDFLAGS when compiling with LTO to get debug
  symbols.

* bpo-5755: Move "-Wstrict-prototypes" option to "CFLAGS_NODIST" from
  "OPT". This option emitted annoying warnings when building extension
  modules written in C++.

* bpo-33614: Ensures module definition files for the stable ABI on
  Windows are correctly regenerated.

* bpo-33648: The –with-c-locale-warning configuration flag has been
  removed. It has had no effect for about a year.

* bpo-33522: Enable CI builds on Visual Studio Team Services at
  https://python.visualstudio.com/cpython

* bpo-33512: configure’s check for “long double” has been simplified

* bpo-33483: C compiler is now correctly detected from the standard
  environment variables. –without-gcc and –with-icc options have been
  removed.

* bpo-33394: Enable the verbose build for extension modules, when GNU
  make is passed macros on the command line.

* bpo-33393: Update config.guess and config.sub files.

* bpo-33377: Add new triplets for mips r6 and riscv variants (used in
  extension suffixes).

* bpo-32232: By default, modules configured in "Modules/Setup" are no
  longer built with "-DPy_BUILD_CORE". Instead, modules that
  specifically need that preprocessor definition include it in their
  individual entries.

* bpo-33182: The embedding tests can once again be built with clang
  6.0

* bpo-33163: Upgrade pip to 9.0.3 and setuptools to v39.0.1.

* bpo-33012: gcc 8 has added a new warning heuristic to detect invalid
  function casts and a stock python build seems to hit that warning
  quite often.  The most common is the cast of a METH_NOARGS function
  (that uses just one argument) to a PyCFunction. Fix this by adding a
  dummy argument to all functions that implement METH_NOARGS.

* bpo-32898: Fix the python debug build when using COUNT_ALLOCS.

* bpo-29442: Replace optparse with argparse in setup.py


Windows
-------

* bpo-35890: Fix API calling consistency of GetVersionEx and wcstok.

* bpo-32560: The "py" launcher now forwards its "STARTUPINFO"
  structure to child processes.

* bpo-35854: Fix EnvBuilder and –symlinks in venv on Windows

* bpo-35811: Avoid propagating venv settings when launching via py.exe

* bpo-35797: Fix default executable used by the multiprocessing module

* bpo-35758: Allow building on ARM with MSVC.

* bpo-29734: Fix handle leaks in os.stat on Windows.

* bpo-35596: Use unchecked PYCs for the embeddable distro to avoid
  zipimport restrictions.

* bpo-35596: Fix vcruntime140.dll being added to embeddable distro
  multiple times.

* bpo-35402: Update Windows build to use Tcl and Tk 8.6.9

* bpo-35401: Updates Windows build to OpenSSL 1.1.0j

* bpo-34977: venv on Windows will now use a python.exe redirector
  rather than copying the actual binaries from the base environment.

* bpo-34977: Adds support for building a Windows App Store package

* bpo-35067: Remove _distutils_findvs module and use vswhere.exe
  instead.

* bpo-32557: Allow shutil.disk_usage to take a file path on Windows

* bpo-34770: Fix a possible null pointer dereference in
  pyshellext.cpp.

* bpo-34603: Fix returning structs from functions produced by MSVC

* bpo-34581: Guard MSVC-specific code in socketmodule.c with "#ifdef
  _MSC_VER".

* bpo-34532: Fixes exit code of list version arguments for py.exe.

* bpo-34062: Fixed the ‘–list’ and ‘–list-paths’ arguments for the
  py.exe launcher

* bpo-34225: Ensure INCLUDE and LIB directories do not end with a
  backslash.

* bpo-34011: A suite of code has been changed which copied across DLLs
  and init.tcl from the running Python location into a venv being
  created. These copies are needed only when running from a Python
  source build, and the copying code is now only run when that is the
  case, rather than whenever a venv is created.

* bpo-34006: Revert line length limit for Windows help docs. The line-
  length limit is not needed because the pages appear in a separate
  app rather than on a browser tab.  It can also interact badly with
  the DPI setting.

* bpo-31546: Restore running PyOS_InputHook while waiting for user
  input at the prompt. The restores integration of interactive GUI
  windows (such as Matplotlib figures) with the prompt on Windows.

* bpo-30237: Output error when ReadConsole is canceled by
  CancelSynchronousIo instead of crashing.

* bpo-33895: GIL is released while calling functions that acquire
  Windows loader lock.

* bpo-33720: Reduces maximum marshal recursion depth on release
  builds.

* bpo-29097: Fix bug where "datetime.fromtimestamp()" erroneously
  throws an "OSError" on Windows for values between 0 and 86400. Patch
  by Ammar Askar.

* bpo-33316: PyThread_release_lock always fails

* bpo-33184: Update Windows installer to use OpenSSL 1.1.0h.

* bpo-32890: Fix usage of GetLastError() instead of errno in
  os.execve() and os.truncate().

* bpo-33016: Fix potential use of uninitialized memory in
  nt._getfinalpathname

* bpo-32903: Fix a memory leak in os.chdir() on Windows if the current
  directory is set to a UNC path.

* bpo-32901: Update Tcl and Tk versions to 8.6.8

* bpo-31966: Fixed WindowsConsoleIO.write() for writing empty data.

* bpo-32409: Ensures activate.bat can handle Unicode contents.

* bpo-32457: Improves handling of denormalized executable path when
  launching Python.

* bpo-32370: Use the correct encoding for ipconfig output in the uuid
  module. Patch by Segev Finer.

* bpo-29248: Fix "os.readlink()" on Windows, which was mistakenly
  treating the "PrintNameOffset" field of the reparse data buffer as a
  number of characters instead of bytes. Patch by Craig Holmquist and
  SSE4.

* bpo-1104: Correctly handle string length in
  "msilib.SummaryInfo.GetProperty()" to prevent it from truncating the
  last character.


macOS
-----

* bpo-35401: Update macOS installer to use OpenSSL 1.1.0j.

* bpo-35025: Properly guard the use of the "CLOCK_GETTIME" et al.
  macros in "timemodule" on macOS.

* bpo-24658: On macOS, fix reading from and writing into a file with a
  size larger than 2 GiB.

* bpo-34405: Update to OpenSSL 1.1.0i for macOS installer builds.

* bpo-33635: In macOS stat on some file descriptors (/dev/fd/3 f.e)
  will result in bad file descriptor OSError. Guard against this
  exception was added in is_dir, is_file and similar methods.
  DirEntry.is_dir can also throw this exception so
  _RecursiveWildcardSelector._iterate_directories was also extended
  with the same error ignoring pattern.

* bpo-13631: The .editrc file in user’s home directory is now
  processed correctly during the readline initialization through
  editline emulation on macOS.

* bpo-33184: Update macOS installer build to use OpenSSL 1.1.0h.

* bpo-32726: Build and link with private copy of Tcl/Tk 8.6 for the
  macOS 10.6+ installer. The 10.9+ installer variant already does
  this.  This means that the Python 3.7 provided by the python.org
  macOS installers no longer need or use any external versions of
  Tcl/Tk, either system-provided or user-installed, such as ActiveTcl.

* bpo-32901: Update macOS 10.9+ installer to Tcl/Tk 8.6.8.

* bpo-31903: In "_scproxy", drop the GIL when calling into
  "SystemConfiguration" to avoid deadlocks.


IDLE
----

* bpo-35770: IDLE macosx deletes Options => Configure IDLE. It
  previously deleted Window => Zoom Height by mistake. (Zoom Height is
  now on the Options menu).  On Mac, the settings dialog is accessed
  via Preferences on the IDLE menu.

* bpo-35769: Change IDLE’s new file name from ‘Untitled’ to ‘untitled’

* bpo-35660: Fix imports in idlelib.window.

* bpo-35641: Proper format "calltip" when the function has no
  docstring.

* bpo-33987: Use ttk Frame for ttk widgets.

* bpo-34055: Fix erroneous ‘smart’ indents and newlines in IDLE Shell.

* bpo-35591: Find Selection now works when selection not found.

* bpo-35196: Speed up squeezer line counting.

* bpo-35598: Update config_key: use PEP 8 names and ttk widgets, make
  some objects global, and add tests.

* bpo-28097: Add Previous/Next History entries to Shell menu.

* bpo-35208: Squeezer now properly counts wrapped lines before
  newlines.

* bpo-35555: Gray out Code Context menu entry when it’s not
  applicable.

* bpo-35521: Document the IDLE editor code context feature. Add some
  internal references within the IDLE doc.

* bpo-22703: The Code Context menu label now toggles between Show/Hide
  Code Context. The Zoom Height menu now toggles between Zoom/Restore
  Height. Zoom Height has moved from the Window menu to the Options
  menu.

* bpo-35213: Where appropriate, use ‘macOS’ in idlelib.

* bpo-34864: On macOS, warn if the system preference “Prefer tabs when
  opening documents” is set to “Always”.

* bpo-34864: Document two IDLE on MacOS issues. The System Preferences
  Dock “prefer tabs always” setting disables some IDLE features.
  Menus are a bit different than as described for Windows and Linux.

* bpo-35202: Remove unused imports from lib/idlelib

* bpo-33000: Document that IDLE’s shell has no line limit. A program
  that runs indefinitely can overfill memory.

* bpo-23220: Explain how IDLE’s Shell displays output.

* bpo-35099: Improve the doc about IDLE running user code.   The
  section is renamed from “IDLE – console differences” is renamed
  “Running user code”. It mostly covers the implications of using
  custom sys.stdxxx objects.

* bpo-35097: Add IDLE doc subsection explaining editor windows. Topics
  include opening, title and status bar, .py* extension, and running.

* bpo-35093: Document the IDLE document viewer in the IDLE doc. Add a
  paragraph in “Help and preferences”, “Help sources” subsection.

* bpo-35088: Update idlelib.help.copy_string docstring. We now use git
  and backporting instead of hg and forward merging.

* bpo-35087: Update idlelib help files for the current doc build. The
  main change is the elimination of chapter-section numbers.

* bpo-34548: Use configured color theme for read-only text views.

* bpo-1529353: Enable “squeezing” of long outputs in the shell, to
  avoid performance degradation and to clean up the history without
  losing it. Squeezed outputs may be copied, viewed in a separate
  window, and “unsqueezed”.

* bpo-34047: Fixed mousewheel scrolling direction on macOS.

* bpo-34275: Make IDLE calltips always visible on Mac. Some MacOS-tk
  combinations need .update_idletasks(). Patch by Kevin Walzer.

* bpo-34120: Fix unresponsiveness after closing certain windows and
  dialogs.

* bpo-33975: Avoid small type when running htests. Since part of the
  purpose of human-viewed tests is to determine that widgets look
  right, it is important that they look the same for testing as when
  running IDLE.

* bpo-33905: Add test for idlelib.stackview.StackBrowser.

* bpo-33924: Change mainmenu.menudefs key ‘windows’ to ‘window’. Every
  other menudef key is lowercase version of main menu entry.

* bpo-33906: Rename idlelib.windows as window Match Window on the main
  menu and remove last plural module name.

* bpo-33917: Fix and document idlelib/idle_test/template.py. The
  revised file compiles, runs, and tests OK.  idle_test/README.txt
  explains how to use it to create new IDLE test files.

* bpo-33904: IDLE: In rstrip, rename class RstripExtension as Rstrip

* bpo-33907: For consistency and clarity, rename an IDLE module and
  classes. Module calltips and its class CallTips are now calltip and
  Calltip. In module calltip_w, class CallTip is now CalltipWindow.

* bpo-33856: Add “help” in the welcome message of IDLE

* bpo-33839: IDLE: refactor ToolTip and CallTip and add documentation
  and tests

* bpo-33855: Minimally test all IDLE modules. Add missing files,
  import module, instantiate classes, and check coverage. Check
  existing files.

* bpo-33656: On Windows, add API call saying that tk scales for DPI.
  On Windows 8.1+ or 10, with DPI compatibility properties of the
  Python binary unchanged, and a monitor resolution greater than 96
  DPI, this should make text and lines sharper.  It should otherwise
  have no effect.

* bpo-33768: Clicking on a context line moves that line to the top of
  the editor window.

* bpo-33763: IDLE: Use read-only text widget for code context instead
  of label widget.

* bpo-33664: Scroll IDLE editor text by lines. Previously, the mouse
  wheel and scrollbar slider moved text by a fixed number of pixels,
  resulting in partial lines at the top of the editor box.  The change
  also applies to the shell and grep output windows, but not to read-
  only text views.

* bpo-33679: Enable theme-specific color configuration for Code
  Context. Use the Highlights tab to see the setting for built-in
  themes or add settings to custom themes.

* bpo-33642: Display up to maxlines non-blank lines for Code Context.
  If there is no current context, show a single blank line.

* bpo-33628: IDLE: Cleanup codecontext.py and its test.

* bpo-33564: IDLE’s code context now recognizes async as a block
  opener.

* bpo-21474: Update word/identifier definition from ascii to unicode.
  In text and entry boxes, this affects selection by double-click,
  movement left/right by control-left/right, and deletion left/right
  by control-BACKSPACE/DEL.

* bpo-33204: IDLE: consistently color invalid string prefixes. A ‘u’
  string prefix cannot be paired with either ‘r’ or ‘f’. Consistently
  color as much of the prefix, starting at the right, as is valid.
  Revise and extend colorizer test.

* bpo-32984: Set "__file__" while running a startup file.  Like
  Python, IDLE optionally runs one startup file in the Shell window
  before presenting the first interactive input prompt.  For IDLE,
  "-s" runs a file named in environmental variable  "IDLESTARTUP" or
  "PYTHONSTARTUP"; "-r file" runs "file".  Python sets "__file__" to
  the startup file name before running the file and unsets it before
  the first prompt.  IDLE now does the same when run normally, without
  the "-n" option.

* bpo-32940: Simplify and rename StringTranslatePseudoMapping in
  pyparse.

* bpo-32916: Change "str" to "code" in pyparse.

* bpo-32905: Remove unused code in pyparse module.

* bpo-32874: Add tests for pyparse.

* bpo-32837: Using the system and place-dependent default encoding for
  open() is a bad idea for IDLE’s system and location-independent
  files.

* bpo-32826: Add “encoding=utf-8” to open() in IDLE’s test_help_about.
  GUI test test_file_buttons() only looks at initial ascii-only lines,
  but failed on systems where open() defaults to ‘ascii’ because
  readline() internally reads and decodes far enough ahead to
  encounter a non-ascii character in CREDITS.txt.

* bpo-32831: Add docstrings and tests for codecontext.

* bpo-32765: Update configdialog General tab docstring to add new
  widgets to the widget list.


Tools/Demos
-----------

* bpo-35884: Add a benchmark script for timing various ways to access
  variables: "Tools/scripts/var_access_benchmark.py".

* bpo-34989: python-gdb.py now handles errors on computing the line
  number of a Python frame.

* bpo-20260: Argument Clinic now has non-bitwise unsigned int
  converters.

* bpo-32962: python-gdb now catches "UnicodeDecodeError" exceptions
  when calling "string()".

* bpo-32962: python-gdb now catches ValueError on read_var(): when
  Python has no debug symbols for example.

* bpo-33189: **pygettext.py** now recognizes only literal strings as
  docstrings and translatable strings, and rejects bytes literals and
  f-string expressions.

* bpo-31920: Fixed handling directories as arguments in the
  "pygettext" script. Based on patch by Oleg Krasnikov.

* bpo-29673: Fix pystackv and pystack gdbinit macros.

* bpo-25427: Remove the pyvenv script in favor of "python3 -m venv" in
  order to lower confusion as to what Python interpreter a virtual
  environment will be created for.

* bpo-32885: Add an "-n" flag for "Tools/scripts/pathfix.py" to
  disable automatic backup creation (files with "~" suffix).

* bpo-32222: Fix pygettext not extracting docstrings for functions
  with type annotated arguments. Patch by Toby Harradine.

* bpo-31583: Fix 2to3 for using with –add-suffix option but without
  –output-dir option for relative path to files in current directory.


C API
-----

* bpo-35713: The "PyByteArray_Init()" and "PyByteArray_Fini()"
  functions have been removed. They did nothing since Python 2.7.4 and
  Python 3.2.0, were excluded from the limited API (stable ABI), and
  were not documented.

* bpo-33817: Fixed "_PyBytes_Resize()" for empty bytes objects.

* bpo-35322: Fix memory leak in "PyUnicode_EncodeLocale()" and
  "PyUnicode_EncodeFSDefault()" on error handling.

* bpo-35059: The following C macros have been converted to static
  inline functions: "Py_INCREF()", "Py_DECREF()", "Py_XINCREF()",
  "Py_XDECREF()", "PyObject_INIT()", "PyObject_INIT_VAR()".

* bpo-35296: "make install" now also installs the internal API:
  "Include/internal/*.h" header files.

* bpo-35081: Internal APIs surrounded by "#ifdef Py_BUILD_CORE" have
  been moved from "Include/*.h" headers to new header files
  "Include/internal/pycore_*.h".

* bpo-35259: Conditionally declare "Py_FinalizeEx()" (new in 3.6)
  based on Py_LIMITED_API. Patch by Arthur Neufeld.

* bpo-35081: The "_PyObject_GC_TRACK()" and "_PyObject_GC_UNTRACK()"
  macros have been removed from the public C API.

* bpo-35134: Creation of a new "Include/cpython/" subdirectory.

* bpo-34725: Adds _Py_SetProgramFullPath so embedders may override
  sys.executable

* bpo-34910: Ensure that "PyObject_Print()" always returns "-1" on
  error.  Patch by Zackery Spytz.

* bpo-34523: Py_DecodeLocale() and Py_EncodeLocale() now use the UTF-8
  encoding on Windows if Py_LegacyWindowsFSEncodingFlag is zero.

* bpo-34193: Fix pluralization in TypeError messages in getargs.c and
  typeobject.c: ‘1 argument’ instead of ‘1 arguments’ and ‘1 element’
  instead of ‘1 elements’.

* bpo-34127: Return grammatically correct error message based on
  argument count. Patch by Karthikeyan Singaravelan.

* bpo-23927: Fixed "SystemError" in "PyArg_ParseTupleAndKeywords()"
  when the "w*" format unit is used for optional parameter.

* bpo-32455: Added "PyCompile_OpcodeStackEffectWithJump()".

* bpo-34008: Py_Main() can again be called after Py_Initialize(), as
  in Python 3.6.

* bpo-32500: Fixed error messages for "PySequence_Size()",
  "PySequence_GetItem()", "PySequence_SetItem()" and
  "PySequence_DelItem()" called with a mapping and "PyMapping_Size()"
  called with a sequence.

* bpo-33818: "PyExceptionClass_Name()" will now return "const char *"
  instead of "char *".

* bpo-33042: Embedding applications may once again call
  PySys_ResetWarnOptions, PySys_AddWarnOption, and PySys_AddXOption
  prior to calling Py_Initialize.

* bpo-32374: Document that m_traverse for multi-phase initialized
  modules can be called with m_state=NULL, and add a sanity check

* bpo-30863: "PyUnicode_AsWideChar()" and
  "PyUnicode_AsWideCharString()" no longer cache the "wchar_t*"
  representation of string objects.


Python 3.7.0 final
==================

*Release date: 2018-06-27*


Library
-------

* bpo-33851: Fix "ast.get_docstring()" for a node that lacks a
  docstring.


C API
-----

* bpo-33932: Calling Py_Initialize() twice does nothing, instead of
  failing with a fatal error: restore the Python 3.6 behaviour.


Python 3.7.0 release candidate 1
================================

*Release date: 2018-06-12*


Core and Builtins
-----------------

* bpo-33803: Fix a crash in hamt.c caused by enabling GC tracking for
  an object that hadn’t all of its fields set to NULL.

* bpo-33706: Fix a crash in Python initialization when parsing the
  command line options. Thanks Christoph Gohlke for the bug report and
  the fix!

* bpo-30654: Fixed reset of the SIGINT handler to SIG_DFL on
  interpreter shutdown even when there was a custom handler set
  previously. Patch by Philipp Kerling.

* bpo-31849: Fix signed/unsigned comparison warning in pyhash.c.


Library
-------

* bpo-30167: Prevent site.main() exception if PYTHONSTARTUP is set.
  Patch by Steve Weber.

* bpo-33812: Datetime instance d with non-None tzinfo, but with
  d.tzinfo.utcoffset(d) returning None is now treated as naive by the
  astimezone() method.

* bpo-30805: Avoid race condition with debug logging

* bpo-33694: asyncio: Fix a race condition causing data loss on
  pause_reading()/resume_reading() when using the ProactorEventLoop.

* bpo-32493: Correct test for "uuid_enc_be" availability in
  "configure.ac". Patch by Michael Felt.

* bpo-33792: Add asyncio.WindowsSelectorEventLoopPolicy and
  asyncio.WindowsProactorEventLoopPolicy.

* bpo-33778: Update "unicodedata"’s database to Unicode version
  11.0.0.

* bpo-33770: improve base64 exception message for encoded inputs of
  invalid length

* bpo-33769: asyncio/start_tls: Fix error message; cancel callbacks in
  case of an unhandled error; mark SSLTransport as closed if it is
  aborted.

* bpo-33767: The concatenation ("+") and repetition ("*") sequence
  operations now raise "TypeError" instead of "SystemError" when
  performed on "mmap.mmap" objects.  Patch by Zackery Spytz.

* bpo-33734: asyncio/ssl: Fix AttributeError, increase default
  handshake timeout

* bpo-11874: Use a better regex when breaking usage into wrappable
  parts. Avoids bogus assertion errors from custom metavar strings.

* bpo-33582: Emit a deprecation warning for inspect.formatargspec


Documentation
-------------

* bpo-33409: Clarified the relationship between **PEP 538**’s
  PYTHONCOERCECLOCALE and PEP 540’s PYTHONUTF8 mode.

* bpo-33736: Improve the documentation of "asyncio.open_connection()",
  "asyncio.start_server()" and their UNIX socket counterparts.

* bpo-31432: Clarify meaning of CERT_NONE, CERT_OPTIONAL, and
  CERT_REQUIRED flags for ssl.SSLContext.verify_mode.


Build
-----

* bpo-5755: Move "-Wstrict-prototypes" option to "CFLAGS_NODIST" from
  "OPT". This option emitted annoying warnings when building extension
  modules written in C++.


Windows
-------

* bpo-33720: Reduces maximum marshal recursion depth on release
  builds.


IDLE
----

* bpo-33656: On Windows, add API call saying that tk scales for DPI.
  On Windows 8.1+ or 10, with DPI compatibility properties of the
  Python binary unchanged, and a monitor resolution greater than 96
  DPI, this should make text and lines sharper.  It should otherwise
  have no effect.

* bpo-33768: Clicking on a context line moves that line to the top of
  the editor window.

* bpo-33763: IDLE: Use read-only text widget for code context instead
  of label widget.

* bpo-33664: Scroll IDLE editor text by lines. Previously, the mouse
  wheel and scrollbar slider moved text by a fixed number of pixels,
  resulting in partial lines at the top of the editor box.  The change
  also applies to the shell and grep output windows, but not to read-
  only text views.

* bpo-33679: Enable theme-specific color configuration for Code
  Context. Use the Highlights tab to see the setting for built-in
  themes or add settings to custom themes.

* bpo-33642: Display up to maxlines non-blank lines for Code Context.
  If there is no current context, show a single blank line.


Python 3.7.0 beta 5
===================

*Release date: 2018-05-30*


Core and Builtins
-----------------

* bpo-33622: Fixed a leak when the garbage collector fails to add an
  object with the "__del__" method or referenced by it into the
  "gc.garbage" list. "PyGC_Collect()" can now be called when an
  exception is set and preserves it.

* bpo-33509: Fix module_globals parameter of warnings.warn_explicit():
  don’t crash if module_globals is not a dict.

* bpo-20104: The new "os.posix_spawn" added in 3.7.0b1 was removed as
  we are still working on what the API should look like.  Expect this
  in 3.8 instead.

* bpo-33475: Fixed miscellaneous bugs in converting annotations to
  strings and optimized parentheses in the string representation.

* bpo-33391: Fix a leak in set_symmetric_difference().

* bpo-28055: Fix unaligned accesses in siphash24(). Patch by Rolf Eike
  Beer.

* bpo-32911: Due to unexpected compatibility issues discovered during
  downstream beta testing, reverted bpo-29463. "docstring" field is
  removed from Module, ClassDef, FunctionDef, and AsyncFunctionDef ast
  nodes which was added in 3.7a1.  Docstring expression is restored as
  a first statement in their body. Based on patch by Inada Naoki.

* bpo-21983: Fix a crash in "ctypes.cast()" in case the type argument
  is a ctypes structured data type. Patch by Eryk Sun and Oren Milman.


Library
-------

* bpo-32751: When cancelling the task due to a timeout,
  "asyncio.wait_for()" will now wait until the cancellation is
  complete.

* bpo-32684: Fix gather to propagate cancellation of itself even with
  return_exceptions.

* bpo-33654: Support protocol type switching in
  SSLTransport.set_protocol().

* bpo-33674: Pause the transport as early as possible to further
  reduce the risk of data_received() being called before
  connection_made().

* bpo-33674: Fix a race condition in SSLProtocol.connection_made() of
  asyncio.sslproto: start immediately the handshake instead of using
  call_soon(). Previously, data_received() could be called before the
  handshake started, causing the handshake to hang or fail.

* bpo-31647: Fixed bug where calling write_eof() on a
  _SelectorSocketTransport after it’s already closed raises
  AttributeError.

* bpo-32610: Make asyncio.all_tasks() return only pending tasks.

* bpo-32410: Avoid blocking on file IO in sendfile fallback code

* bpo-33469: Fix RuntimeError after closing loop that used
  run_in_executor

* bpo-33672: Fix Task.__repr__ crash with Cython’s bogus coroutines

* bpo-33654: Fix transport.set_protocol() to support switching between
  asyncio.Protocol and asyncio.BufferedProtocol.  Fix loop.start_tls()
  to work with asyncio.BufferedProtocols.

* bpo-33652: Pickles of type variables and subscripted generics are
  now future-proof and compatible with older Python versions.

* bpo-32493: Fixed "uuid.uuid1()" on FreeBSD.

* bpo-33618: Finalize and document preliminary and experimental TLS
  1.3 support with OpenSSL 1.1.1

* bpo-33623: Fix possible SIGSGV when asyncio.Future is created in
  __del__

* bpo-30877: Fixed a bug in the Python implementation of the JSON
  decoder that prevented the cache of parsed strings from clearing
  after finishing the decoding. Based on patch by c-fos.

* bpo-33570: Change TLS 1.3 cipher suite settings for compatibility
  with OpenSSL 1.1.1-pre6 and newer. OpenSSL 1.1.1 will have TLS 1.3
  ciphers enabled by default.

* bpo-28556: Do not simplify arguments to "typing.Union". Now
  "Union[Manager, Employee]" is not simplified to "Employee" at
  runtime. Such simplification previously caused several bugs and
  limited possibilities for introspection.

* bpo-33540: Add a new "block_on_close" class attribute to
  "ForkingMixIn" and "ThreadingMixIn" classes of "socketserver".

* bpo-33548: tempfile._candidate_tempdir_list should consider common
  TEMP locations

* bpo-33109: argparse subparsers are once again not required by
  default, reverting the change in behavior introduced by bpo-26510 in
  3.7.0a2.

* bpo-33536: dataclasses.make_dataclass now checks for invalid field
  names and duplicate fields. Also, added a check for invalid field
  specifications.

* bpo-33542: Prevent "uuid.get_node" from using a DUID instead of a
  MAC on Windows. Patch by Zvi Effron

* bpo-26819: Fix race condition with "ReadTransport.resume_reading" in
  Windows proactor event loop.

* Fix failure in "typing.get_type_hints()" when ClassVar was provided
  as a string forward reference.

* bpo-33505: Optimize asyncio.ensure_future() by reordering if checks:
  1.17x faster.

* bpo-33497: Add errors param to cgi.parse_multipart and make an
  encoding in FieldStorage use the given errors (needed for Twisted).
  Patch by Amber Brown.

* bpo-33495: Change dataclasses.Fields repr to use the repr of each of
  its members, instead of str.  This makes it more clear what each
  field actually represents.  This is especially true for the ‘type’
  member.

* bpo-33453: Fix dataclasses to work if using literal string type
  annotations or if using PEP 563 “Postponed Evaluation of
  Annotations”. Only specific string prefixes are detected for both
  ClassVar (“ClassVar” and “typing.ClassVar”) and InitVar (“InitVar”
  and “dataclasses.InitVar”).

* bpo-28556: Minor fixes in typing module: add annotations to
  "NamedTuple.__new__", pass "*args" and "**kwds" in
  "Generic.__new__".  Original PRs by Paulius Šarka and Chad Dombrova.

* bpo-20087: Updated alias mapping with glibc 2.27 supported locales.

* bpo-33422: Fix trailing quotation marks getting deleted when looking
  up byte/string literals on pydoc. Patch by Andrés Delfino.

* bpo-28167: The function "platform.linux_distribution" and
  "platform.dist" now trigger a "DeprecationWarning" and have been
  marked for removal in Python 3.8

* bpo-33197: Update error message when constructing invalid
  inspect.Parameters Patch by Dong-hee Na.

* bpo-33263: Fix FD leak in "_SelectorSocketTransport"  Patch by Vlad
  Starostin.

* bpo-32861: The urllib.robotparser’s "__str__" representation now
  includes wildcard entries and the “Crawl-delay” and “Request-rate”
  fields. Patch by Michael Lazar.

* bpo-32257: The ssl module now contains OP_NO_RENEGOTIATION constant,
  available with OpenSSL 1.1.0h or 1.1.1.

* bpo-16865: Support arrays >=2GiB in "ctypes".  Patch by Segev Finer.


Documentation
-------------

* bpo-23859: Document that "asyncio.wait()" does not cancel its
  futures on timeout.

* bpo-32436: Document **PEP 567** changes to asyncio.

* bpo-33604: Update HMAC md5 default to a DeprecationWarning, bump
  removal to 3.8.

* bpo-33503: Fix broken pypi link

* bpo-33421: Add missing documentation for
  "typing.AsyncContextManager".


Tests
-----

* bpo-33655: Ignore test_posix_fallocate failures on BSD platforms
  that might be due to running on ZFS.

* bpo-32604: Remove the _xxsubinterpreters module (meant for testing)
  and associated helpers.  This module was originally added recently
  in 3.7b1.


Build
-----

* bpo-33614: Ensures module definition files for the stable ABI on
  Windows are correctly regenerated.

* bpo-33522: Enable CI builds on Visual Studio Team Services at
  https://python.visualstudio.com/cpython

* bpo-33012: Add "-Wno-cast-function-type" for gcc 8 for silencing
  warnings about function casts like casting to PyCFunction in method
  definition lists.


macOS
-----

* bpo-13631: The .editrc file in user’s home directory is now
  processed correctly during the readline initialization through
  editline emulation on macOS.


IDLE
----

* bpo-33628: IDLE: Cleanup codecontext.py and its test.

* bpo-33564: IDLE’s code context now recognizes async as a block
  opener.

* bpo-32831: Add docstrings and tests for codecontext.


Python 3.7.0 beta 4
===================

*Release date: 2018-05-02*


Core and Builtins
-----------------

* bpo-33363: Raise a SyntaxError for "async with" and "async for"
  statements outside of async functions.

* bpo-33128: Fix a bug that causes PathFinder to appear twice on
  sys.meta_path. Patch by Pablo Galindo Salgado.

* bpo-33312: Fixed clang ubsan (undefined behavior sanitizer) warnings
  in dictobject.c by adjusting how the internal struct _dictkeysobject
  shared keys structure is declared.

* bpo-33231: Fix potential memory leak in "normalizestring()".

* bpo-33205: Change dict growth function from
  "round_up_to_power_2(used*2+hashtable_size/2)" to
  "round_up_to_power_2(used*3)".  Previously, dict is shrinked only
  when "used == 0". Now dict has more chance to be shrinked.

* bpo-29922: Improved error messages in ‘async with’ when
  "__aenter__()" or "__aexit__()" return non-awaitable object.

* bpo-33199: Fix "ma_version_tag" in dict implementation is
  uninitialized when copying from key-sharing dict.


Library
-------

* bpo-33281: Fix ctypes.util.find_library regression on macOS.

* bpo-33383: Fixed crash in the get() method of the "dbm.ndbm"
  database object when it is called with a single argument.

* bpo-33329: Fix multiprocessing regression on newer glibcs

* bpo-991266: Fix quoting of the "Comment" attribute of
  "http.cookies.SimpleCookie".

* bpo-33131: Upgrade bundled version of pip to 10.0.1.

* bpo-33308: Fixed a crash in the "parser" module when converting an
  ST object to a tree of tuples or lists with "line_info=False" and
  "col_info=True".

* bpo-33266: lib2to3 now recognizes "rf'...'" strings.

* bpo-11594: Ensure line-endings are respected when using lib2to3.

* bpo-33254: Have "importlib.resources.contents()" and
  "importlib.abc.ResourceReader.contents()" return an *iterable*
  instead of an *iterator*.

* bpo-33256: Fix display of "<module>" call in the html produced by
  "cgitb.html()". Patch by Stéphane Blondon.

* bpo-33185: Fixed regression when running pydoc with the "-m" switch.
  (The regression was introduced in 3.7.0b3 by the resolution of
  bpo-33053) This fix also changed pydoc to add "os.getcwd()" to
  "sys.path" when necessary, rather than adding ""."".

* bpo-33169: Delete entries of "None" in "sys.path_importer_cache"
  when "importlib.machinery.invalidate_caches()" is called.

* bpo-33217: Deprecate looking up non-Enum objects in Enum classes and
  Enum members (will raise "TypeError" in 3.8+).

* bpo-33203: "random.Random.choice()" now raises "IndexError" for
  empty sequences consistently even when called from subclasses
  without a "getrandbits()" implementation.

* bpo-33224: Update difflib.mdiff() for **PEP 479**.  Convert an
  uncaught StopIteration in a generator into a return-statement.

* bpo-33209: End framing at the end of C implementation of
  "pickle.Pickler.dump()".

* bpo-20104: Improved error handling and fixed a reference leak in
  "os.posix_spawn()".

* bpo-33175: In dataclasses, Field.__set_name__ now looks up the
  __set_name__ special method on the class, not the instance, of the
  default value.

* bpo-33097: Raise RuntimeError when "executor.submit" is called
  during interpreter shutdown.

* bpo-31908: Fix output of cover files for "trace" module command-line
  tool. Previously emitted cover files only when "--missing" option
  was used. Patch by Michael Selik.


Documentation
-------------

* bpo-33378: Add Korean language switcher for
  https://docs.python.org/3/

* bpo-33276: Clarify that the "__path__" attribute on modules cannot
  be just any value.

* bpo-33201: Modernize documentation for writing C extension types.

* bpo-33195: Deprecate "Py_UNICODE" usage in "c-api/arg" document.
  "Py_UNICODE" related APIs are deprecated since Python 3.3, but it is
  missed in the document.

* bpo-8243: Add a note about curses.addch and curses.addstr exception
  behavior when writing outside a window, or pad.

* bpo-32337: Update documentation related with "dict" order.


Tests
-----

* bpo-33358: Fix "test_embed.test_pre_initialization_sys_options()"
  when the interpreter is built with "--enable-shared".


Build
-----

* bpo-33394: Enable the verbose build for extension modules, when GNU
  make is passed macros on the command line.

* bpo-33393: Update config.guess and config.sub files.

* bpo-33377: Add new triplets for mips r6 and riscv variants (used in
  extension suffixes).

* bpo-32232: By default, modules configured in "Modules/Setup" are no
  longer built with "-DPy_BUILD_CORE". Instead, modules that
  specifically need that preprocessor definition include it in their
  individual entries.

* bpo-33182: The embedding tests can once again be built with clang
  6.0


Windows
-------

* bpo-33184: Update Windows installer to use OpenSSL 1.1.0h.


macOS
-----

* bpo-33184: Update macOS installer build to use OpenSSL 1.1.0h.


IDLE
----

* bpo-21474: Update word/identifier definition from ascii to unicode.
  In text and entry boxes, this affects selection by double-click,
  movement left/right by control-left/right, and deletion left/right
  by control-BACKSPACE/DEL.

* bpo-33204: IDLE: consistently color invalid string prefixes. A ‘u’
  string prefix cannot be paired with either ‘r’ or ‘f’. Consistently
  color as much of the prefix, starting at the right, as is valid.
  Revise and extend colorizer test.


Tools/Demos
-----------

* bpo-33189: **pygettext.py** now recognizes only literal strings as
  docstrings and translatable strings, and rejects bytes literals and
  f-string expressions.

* bpo-31920: Fixed handling directories as arguments in the
  "pygettext" script. Based on patch by Oleg Krasnikov.

* bpo-29673: Fix pystackv and pystack gdbinit macros.

* bpo-31583: Fix 2to3 for using with –add-suffix option but without
  –output-dir option for relative path to files in current directory.


Python 3.7.0 beta 3
===================

*Release date: 2018-03-29*


Security
--------

* bpo-33136: Harden ssl module against LibreSSL CVE-2018-8970.
  X509_VERIFY_PARAM_set1_host() is called with an explicit namelen. A
  new test ensures that NULL bytes are not allowed.

* bpo-33001: Minimal fix to prevent buffer overrun in os.symlink on
  Windows

* bpo-32981: Regexes in difflib and poplib were vulnerable to
  catastrophic backtracking. These regexes formed potential DOS
  vectors (REDOS). They have been refactored. This resolves
  CVE-2018-1060 and CVE-2018-1061. Patch by Jamie Davis.


Core and Builtins
-----------------

* bpo-33053: When using the -m switch, sys.path[0] is now explicitly
  expanded as the *starting* working directory, rather than being left
  as the empty path (which allows imports from the current working
  directory at the time of the import)

* bpo-33018: Improve consistency of errors raised by "issubclass()"
  when called with a non-class and an abstract base class as the first
  and second arguments, respectively. Patch by Josh Bronson.

* bpo-33041: Fixed jumping when the function contains an "async for"
  loop.

* bpo-33026: Fixed jumping out of “with” block by setting f_lineno.

* bpo-33005: Fix a crash on fork when using a custom memory allocator
  (ex: using PYTHONMALLOC env var). _PyGILState_Reinit() and
  _PyInterpreterState_Enable() now use the default RAW memory
  allocator to allocate a new interpreters mutex on fork.

* bpo-17288: Prevent jumps from ‘return’ and ‘exception’ trace events.

* bpo-32836: Don’t use temporary variables in cases of list/dict/set
  comprehensions


Library
-------

* bpo-33141: Have Field objects pass through __set_name__ to their
  default values, if they have their own __set_name__.

* bpo-33096: Allow ttk.Treeview.insert to insert iid that has a false
  boolean value. Note iid=0 and iid=False would be same. Patch by
  Garvit Khatri.

* bpo-32873: Treat type variables and special typing forms as
  immutable by copy and pickle.  This fixes several minor issues and
  inconsistencies, and improves backwards compatibility with Python
  3.6.

* bpo-33134: When computing dataclass’s __hash__, use the lookup table
  to contain the function which returns the __hash__ value.  This is
  an improvement over looking up a string, and then testing that
  string to see what to do.

* bpo-33127: The ssl module now compiles with LibreSSL 2.7.1.

* bpo-32505: Raise TypeError if a member variable of a dataclass is of
  type Field, but doesn’t have a type annotation.

* bpo-33078: Fix the failure on OSX caused by the tests relying on
  sem_getvalue

* bpo-33116: Add ‘Field’ to dataclasses.__all__.

* bpo-32896: Fix an error where subclassing a dataclass with a field
  that uses a default_factory would generate an incorrect class.

* bpo-33100: Dataclasses: If a field has a default value that’s a
  MemberDescriptorType, then it’s from that field being in __slots__,
  not an actual default value.

* bpo-32953: If a non-dataclass inherits from a frozen dataclass,
  allow attributes to be added to the derived class.  Only attributes
  from the frozen dataclass cannot be assigned to.  Require all
  dataclasses in a hierarchy to be either all frozen or all non-
  frozen.

* bpo-33061: Add missing "NoReturn" to "__all__" in typing.py

* bpo-33078: Fix the size handling in multiprocessing.Queue when a
  pickling error occurs.

* bpo-33064: lib2to3 now properly supports trailing commas after
  "*args" and "**kwargs" in function signatures.

* bpo-33056: FIX properly close leaking fds in
  concurrent.futures.ProcessPoolExecutor.

* bpo-33021: Release the GIL during fstat() calls, avoiding hang of
  all threads when calling mmap.mmap(), os.urandom(), and
  random.seed().  Patch by Nir Soffer.

* bpo-31804: Avoid failing in multiprocessing.Process if the standard
  streams are closed or None at exit.

* bpo-33037: Skip sending/receiving data after SSL transport closing.

* bpo-27683: Fix a regression in "ipaddress" that result of "hosts()"
  is empty when the network is constructed by a tuple containing an
  integer mask and only 1 bit left for addresses.

* bpo-32999: Fix C implementation of "ABC.__subclasscheck__(cls,
  subclass)" crashed when "subclass" is not a type object.

* bpo-33009: Fix inspect.signature() for single-parameter
  partialmethods.

* bpo-32969: Expose several missing constants in zlib and fix
  corresponding documentation.

* bpo-32056: Improved exceptions raised for invalid number of channels
  and sample width when read an audio file in modules "aifc", "wave"
  and "sunau".

* bpo-32844: Fix wrong redirection of a low descriptor (0 or 1) to
  stderr in subprocess if another low descriptor is closed.

* bpo-32857: In "tkinter", "after_cancel(None)" now raises a
  "ValueError" instead of canceling the first scheduled function.
  Patch by Cheryl Sabella.

* bpo-31639: http.server now exposes a ThreadedHTTPServer class and
  uses it when the module is run with "-m" to cope with web browsers
  pre-opening sockets.

* bpo-27645: "sqlite3.Connection" now exposes a "backup" method, if
  the underlying SQLite library is at version 3.6.11 or higher.  Patch
  by Lele Gaifax.


Documentation
-------------

* bpo-33126: Document PyBuffer_ToContiguous().

* bpo-27212: Modify documentation for the "islice()" recipe to consume
  initial values up to the start index.

* bpo-28247: Update "zipapp" documentation to describe how to make
  standalone applications.

* bpo-18802: Documentation changes for ipaddress.  Patch by Jon Foster
  and Berker Peksag.

* bpo-27428: Update documentation to clarify that
  "WindowsRegistryFinder" implements "MetaPathFinder". (Patch by
  Himanshu Lakhara)


Tests
-----

* bpo-32872: Avoid regrtest compatibility issue with namespace
  packages.

* bpo-32517: Fix failing "test_asyncio" on macOS 10.12.2+ due to
  transport of "KqueueSelector" loop was not being closed.

* bpo-19417: Add test_bdb.py.


Build
-----

* bpo-33163: Upgrade pip to 9.0.3 and setuptools to v39.0.1.


Windows
-------

* bpo-33016: Fix potential use of uninitialized memory in
  nt._getfinalpathname

* bpo-32903: Fix a memory leak in os.chdir() on Windows if the current
  directory is set to a UNC path.


macOS
-----

* bpo-32726: Build and link with private copy of Tcl/Tk 8.6 for the
  macOS 10.6+ installer. The 10.9+ installer variant already does
  this.  This means that the Python 3.7 provided by the python.org
  macOS installers no longer need or use any external versions of
  Tcl/Tk, either system-provided or user-installed, such as ActiveTcl.


IDLE
----

* bpo-32984: Set "__file__" while running a startup file.  Like
  Python, IDLE optionally runs one startup file in the Shell window
  before presenting the first interactive input prompt.  For IDLE,
  "-s" runs a file named in environmental variable  "IDLESTARTUP" or
  "PYTHONSTARTUP"; "-r file" runs "file".  Python sets "__file__" to
  the startup file name before running the file and unsets it before
  the first prompt.  IDLE now does the same when run normally, without
  the "-n" option.

* bpo-32940: Simplify and rename StringTranslatePseudoMapping in
  pyparse.


Tools/Demos
-----------

* bpo-32885: Add an "-n" flag for "Tools/scripts/pathfix.py" to
  disable automatic backup creation (files with "~" suffix).


C API
-----

* bpo-33042: Embedding applications may once again call
  PySys_ResetWarnOptions, PySys_AddWarnOption, and PySys_AddXOption
  prior to calling Py_Initialize.

* bpo-32374: Document that m_traverse for multi-phase initialized
  modules can be called with m_state=NULL, and add a sanity check


Python 3.7.0 beta 2
===================

*Release date: 2018-02-27*


Security
--------

* bpo-28414: The ssl module now allows users to perform their own IDN
  en/decoding when using SNI.


Core and Builtins
-----------------

* bpo-32889: Update Valgrind suppression list to account for the
  rename of "Py_ADDRESS_IN_RANG" to "address_in_range".

* bpo-31356: Remove the new API added in bpo-31356
  (gc.ensure_disabled() context manager).

* bpo-32305: For namespace packages, ensure that both "__file__" and
  "__spec__.origin" are set to None.

* bpo-32303: Make sure "__spec__.loader" matches "__loader__" for
  namespace packages.

* bpo-32711: Fix the warning messages for Python/ast_unparse.c. Patch
  by Stéphane Wirtel

* bpo-32583: Fix possible crashing in builtin Unicode decoders caused
  by write out-of-bound errors when using customized decode error
  handlers.


Library
-------

* bpo-32960: For dataclasses, disallow inheriting frozen from non-
  frozen classes, and also disallow inheriting non-frozen from frozen
  classes. This restriction will be relaxed at a future date.

* bpo-32713: Fixed tarfile.itn handling of out-of-bounds float values.
  Patch by Joffrey Fuhrer.

* bpo-32951: Direct instantiation of SSLSocket and SSLObject objects
  is now prohibited. The constructors were never documented, tested,
  or designed as public constructors. Users were suppose to use
  ssl.wrap_socket() or SSLContext.

* bpo-32929: Remove the tri-state parameter “hash”, and add the
  boolean “unsafe_hash”. If unsafe_hash is True, add a __hash__
  function, but if a __hash__ exists, raise TypeError.  If unsafe_hash
  is False, add a __hash__ based on the values of eq= and frozen=.
  The unsafe_hash=False behavior is the same as the old hash=None
  behavior.  unsafe_hash=False is the default, just as hash=None used
  to be.

* bpo-32947: Add OP_ENABLE_MIDDLEBOX_COMPAT and test workaround for
  TLSv1.3 for future compatibility with OpenSSL 1.1.1.

* bpo-30622: The ssl module now detects missing NPN support in
  LibreSSL.

* bpo-32922: dbm.open() now encodes filename with the filesystem
  encoding rather than default encoding.

* bpo-32859: In "os.dup2", don’t check every call whether the "dup3"
  syscall exists or not.

* bpo-32556: nt._getfinalpathname, nt._getvolumepathname and
  nt._getdiskusage now correctly convert from bytes.

* bpo-25988: Emit a "DeprecationWarning" when using or importing an
  ABC directly from "collections" rather than from "collections.abc".

* bpo-21060: Rewrite confusing message from setup.py upload from “No
  dist file created in earlier command” to the more helpful “Must
  create and upload files in one command”.

* bpo-32852: Make sure sys.argv remains as a list when running trace.

* bpo-31333: "_abc" module is added.  It is a speedup module with C
  implementations for various functions and methods in "abc".
  Creating an ABC subclass and calling "isinstance" or "issubclass"
  with an ABC subclass are up to 1.5x faster. In addition, this makes
  Python start-up up to 10% faster. Note that the new implementation
  hides internal registry and caches, previously accessible via
  private attributes "_abc_registry", "_abc_cache", and
  "_abc_negative_cache".  There are three debugging helper methods
  that can be used instead "_dump_registry", "_abc_registry_clear",
  and "_abc_caches_clear".

* bpo-32841: Fixed "asyncio.Condition" issue which silently ignored
  cancellation after notifying and cancelling a conditional lock.
  Patch by Bar Harel.

* bpo-32819: ssl.match_hostname() has been simplified and no longer
  depends on re and ipaddress module for wildcard and IP addresses.
  Error reporting for invalid wildcards has been improved.

* bpo-32394: socket: Remove
  TCP_FASTOPEN,TCP_KEEPCNT,TCP_KEEPIDLE,TCP_KEEPINTVL flags on older
  version Windows during run-time.

* bpo-31787: Fixed refleaks of "__init__()" methods in various
  modules. (Contributed by Oren Milman)

* bpo-30157: Fixed guessing quote and delimiter in csv.Sniffer.sniff()
  when only the last field is quoted.  Patch by Jake Davis.

* bpo-32792: collections.ChainMap() preserves the order of the
  underlying mappings.

* bpo-32775: "fnmatch.translate()" no longer produces patterns which
  contain set operations. Sets starting with ‘[’ or containing ‘–’,
  ‘&&’, ‘~~’ or ‘||’ will be interpreted differently in regular
  expressions in future versions. Currently they emit warnings.
  fnmatch.translate() now avoids producing patterns containing such
  sets by accident.

* bpo-32622: Implement native fast sendfile for Windows proactor event
  loop.

* bpo-32777: Fix a rare but potential pre-exec child process deadlock
  in subprocess on POSIX systems when marking file descriptors
  inheritable on exec in the child process.  This bug appears to have
  been introduced in 3.4.

* bpo-32647: The ctypes module used to depend on indirect linking for
  dlopen. The shared extension is now explicitly linked against libdl
  on platforms with dl.

* bpo-32741: Implement "asyncio.TimerHandle.when()" method.

* bpo-32691: Use mod_spec.parent when running modules with pdb

* bpo-32734: Fixed "asyncio.Lock()" safety issue which allowed
  acquiring and locking the same lock multiple times, without it being
  free. Patch by Bar Harel.

* bpo-32727: Do not include name field in SMTP envelope from address.
  Patch by Stéphane Wirtel

* bpo-31453: Add TLSVersion constants and SSLContext.maximum_version /
  minimum_version attributes. The new API wraps OpenSSL 1.1 https://w
  ww.openssl.org/docs/man1.1.0/ssl/SSL_CTX_set_min_proto_version.html
  feature.

* bpo-24334: Internal implementation details of ssl module were
  cleaned up. The SSLSocket has one less layer of indirection. Owner
  and session information are now handled by the SSLSocket and
  SSLObject constructor. Channel binding implementation has been
  simplified.

* bpo-31848: Fix the error handling in Aifc_read.initfp() when the
  SSND chunk is not found. Patch by Zackery Spytz.

* bpo-32585: Add Ttk spinbox widget to "tkinter.ttk".  Patch by Alan D
  Moore.

* bpo-32221: Various functions returning tuple containing IPv6
  addresses now omit "%scope" part since the same information is
  already encoded in *scopeid* tuple item. Especially this speeds up
  "socket.recvfrom()" when it receives multicast packet since useless
  resolving of network interface name is omitted.

* bpo-30693: The TarFile class now recurses directories in a
  reproducible way.

* bpo-30693: The ZipFile class now recurses directories in a
  reproducible way.


Documentation
-------------

* bpo-28124: The ssl module function ssl.wrap_socket() has been de-
  emphasized and deprecated in favor of the more secure and efficient
  SSLContext.wrap_socket() method.

* bpo-17232: Clarify docs for -O and -OO.  Patch by Terry Reedy.

* bpo-32436: Add documentation for the contextvars module (PEP 567).

* bpo-32800: Update link to w3c doc for xml default namespaces.

* bpo-11015: Update "test.support" documentation.

* bpo-8722: Document "__getattr__()" behavior when property "get()"
  method raises "AttributeError".

* bpo-32614: Modify RE examples in documentation to use raw strings to
  prevent "DeprecationWarning" and add text to REGEX HOWTO to
  highlight the deprecation.

* bpo-31972: Improve docstrings for "pathlib.PurePath" subclasses.


Tests
-----

* bpo-31809: Add tests to verify connection with secp ECDH curves.


Build
-----

* bpo-32898: Fix the python debug build when using COUNT_ALLOCS.


Windows
-------

* bpo-32901: Update Tcl and Tk versions to 8.6.8

* bpo-31966: Fixed WindowsConsoleIO.write() for writing empty data.

* bpo-32409: Ensures activate.bat can handle Unicode contents.

* bpo-32457: Improves handling of denormalized executable path when
  launching Python.

* bpo-32370: Use the correct encoding for ipconfig output in the uuid
  module. Patch by Segev Finer.

* bpo-29248: Fix "os.readlink()" on Windows, which was mistakenly
  treating the "PrintNameOffset" field of the reparse data buffer as a
  number of characters instead of bytes. Patch by Craig Holmquist and
  SSE4.


macOS
-----

* bpo-32901: Update macOS 10.9+ installer to Tcl/Tk 8.6.8.


IDLE
----

* bpo-32916: Change "str" to "code" in pyparse.

* bpo-32905: Remove unused code in pyparse module.

* bpo-32874: Add tests for pyparse.

* bpo-32837: Using the system and place-dependent default encoding for
  open() is a bad idea for IDLE’s system and location-independent
  files.

* bpo-32826: Add “encoding=utf-8” to open() in IDLE’s test_help_about.
  GUI test test_file_buttons() only looks at initial ascii-only lines,
  but failed on systems where open() defaults to ‘ascii’ because
  readline() internally reads and decodes far enough ahead to
  encounter a non-ascii character in CREDITS.txt.

* bpo-32765: Update configdialog General tab docstring to add new
  widgets to the widget list.


Tools/Demos
-----------

* bpo-32222: Fix pygettext not extracting docstrings for functions
  with type annotated arguments. Patch by Toby Harradine.


Python 3.7.0 beta 1
===================

*Release date: 2018-01-30*


Core and Builtins
-----------------

* bpo-32703: Fix coroutine’s ResourceWarning when there’s an active
  error set when it’s being finalized.

* bpo-32650: Pdb and other debuggers dependent on bdb.py will
  correctly step over (next command) native coroutines. Patch by Pablo
  Galindo.

* bpo-28685: Optimize list.sort() and sorted() by using type
  specialized comparisons when possible.

* bpo-32685: Improve suggestion when the Python 2 form of print
  statement is either present on the same line as the header of a
  compound statement or else terminated by a semi-colon instead of a
  newline. Patch by Nitish Chandra.

* bpo-32697: Python now explicitly preserves the definition order of
  keyword-only parameters.  It’s always preserved their order, but
  this behavior was never guaranteed before; this behavior is now
  guaranteed and tested.

* bpo-32690: The locals() dictionary now displays in the lexical order
  that variables were defined.  Previously, the order was reversed.

* bpo-32677: Add ".isascii()" method to "str", "bytes" and
  "bytearray". It can be used to test that string contains only ASCII
  characters.

* bpo-32670: Enforce **PEP 479** for all code. This means that
  manually raising a StopIteration exception from a generator is
  prohibited for all code, regardless of whether ‘from __future__
  import generator_stop’ was used or not.

* bpo-32591: Added built-in support for tracking the origin of
  coroutine objects; see sys.set_coroutine_origin_tracking_depth and
  CoroutineType.cr_origin. This replaces the asyncio debug mode’s use
  of coroutine wrapping for native coroutine objects.

* bpo-31368: Expose preadv and pwritev system calls in the os module.
  Patch by Pablo Galindo

* bpo-32544: "hasattr(obj, name)" and "getattr(obj, name, default)"
  are about 4 times faster than before when "name" is not found and
  "obj" doesn’t override "__getattr__" or "__getattribute__".

* bpo-26163: Improved frozenset() hash to create more distinct hash
  values when faced with datasets containing many similar values.

* bpo-32550: Remove the STORE_ANNOTATION bytecode.

* bpo-20104: Expose posix_spawn as a low level API in the os module.
  (removed before 3.7.0rc1)

* bpo-24340: Fixed estimation of the code stack size.

* bpo-32436: Implement **PEP 567** Context Variables.

* bpo-18533: "repr()" on a dict containing its own "values()" or
  "items()" no longer raises "RecursionError"; OrderedDict similarly.
  Instead, use "...", as for other recursive structures.  Patch by Ben
  North.

* bpo-20891: Py_Initialize() now creates the GIL. The GIL is no longer
  created “on demand” to fix a race condition when PyGILState_Ensure()
  is called in a non-Python thread.

* bpo-32028: Leading whitespace is now correctly ignored when
  generating suggestions for converting Py2 print statements to Py3
  builtin print function calls. Patch by Sanyam Khurana.

* bpo-31179: Make dict.copy() up to 5.5 times faster.

* bpo-31113: Get rid of recursion in the compiler for normal control
  flow.


Library
-------

* bpo-25988: Deprecate exposing the contents of collections.abc in the
  regular collections module.

* bpo-31429: The default cipher suite selection of the ssl module now
  uses a blacklist approach rather than a hard-coded whitelist. Python
  no longer re-enables ciphers that have been blocked by OpenSSL
  security update. Default cipher suite selection can be configured on
  compile time.

* bpo-30306: contextlib.contextmanager now releases the arguments
  passed to the underlying generator as soon as the context manager is
  entered. Previously it would keep them alive for as long as the
  context manager was alive, even when not being used as a function
  decorator. Patch by Martin Teichmann.

* bpo-21417: Added support for setting the compression level for
  zipfile.ZipFile.

* bpo-32251: Implement asyncio.BufferedProtocol (provisional API).

* bpo-32513: In dataclasses, allow easier overriding of dunder methods
  without specifying decorator parameters.

* bpo-32660: "termios" makes available "FIONREAD", "FIONCLEX",
  "FIOCLEX", "FIOASYNC" and "FIONBIO" also under Solaris/derivatives.

* bpo-27931: Fix email address header parsing error when the username
  is an empty quoted string. Patch by Xiang Zhang.

* bpo-32659: Under Solaris and derivatives, "os.stat_result" provides
  a st_fstype attribute.

* bpo-32662: Implement Server.start_serving(), Server.serve_forever(),
  and Server.is_serving() methods.  Add ‘start_serving’ keyword
  parameter to loop.create_server() and loop.create_unix_server().

* bpo-32391: Implement "asyncio.StreamWriter.wait_closed()" and
  "asyncio.StreamWriter.is_closing()" methods

* bpo-32643: Make Task._step, Task._wakeup and
  Future._schedule_callbacks methods private.

* bpo-32630: Refactor decimal module to use contextvars to store
  decimal context.

* bpo-32622: Add "asyncio.AbstractEventLoop.sendfile()" method.

* bpo-32304: distutils’ upload command no longer corrupts tar files
  ending with a CR byte, and no longer tries to convert CR to CRLF in
  any of the upload text fields.

* bpo-32502: uuid.uuid1 no longer raises an exception if a 64-bit
  hardware address is encountered.

* bpo-32596: "concurrent.futures" imports "ThreadPoolExecutor" and
  "ProcessPoolExecutor" lazily (using **PEP 562**). It makes "import
  asyncio" about 15% faster because asyncio uses only
  "ThreadPoolExecutor" by default.

* bpo-31801: Add "_ignore_" to "Enum" so temporary variables can be
  used during class construction without being turned into members.

* bpo-32576: Use queue.SimpleQueue() in places where it can be invoked
  from a weakref callback.

* bpo-32574: Fix memory leak in asyncio.Queue, when the queue has
  limited size and it is full, the cancelation of queue.put() can
  cause a memory leak. Patch by: José Melero.

* bpo-32521: The nis module is now compatible with new libnsl and
  headers location.

* bpo-32467: collections.abc.ValuesView now inherits from
  collections.abc.Collection.

* bpo-32473: Improve ABCMeta._dump_registry() output readability

* bpo-32102: New argument "capture_output" for subprocess.run

* bpo-32521: glibc has removed Sun RPC. Use replacement libtirpc
  headers and library in nis module.

* bpo-32493: UUID module fixes build for FreeBSD/OpenBSD

* bpo-32503: Pickling with protocol 4 no longer creates too small
  frames.

* bpo-29237: Create enum for pstats sorting options

* bpo-32454: Add close(fd) function to the socket module.

* bpo-25942: The subprocess module is now more graceful when handling
  a Ctrl-C KeyboardInterrupt during subprocess.call, subprocess.run,
  or a Popen context manager.  It now waits a short amount of time for
  the child (presumed to have also gotten the SIGINT) to exit, before
  continuing the KeyboardInterrupt exception handling.  This still
  includes a SIGKILL in the call() and run() APIs, but at least the
  child had a chance first.

* bpo-32433: The hmac module now has hmac.digest(), which provides an
  optimized HMAC digest.

* bpo-28134: Sockets now auto-detect family, type and protocol from
  file descriptor by default.

* bpo-32404: Fix bug where "datetime.datetime.fromtimestamp()" did not
  call __new__ in "datetime.datetime" subclasses.

* bpo-32403: Improved speed of "datetime.date" and "datetime.datetime"
  alternate constructors.

* bpo-32228: Ensure that "truncate()" preserves the file position (as
  reported by "tell()") after writes longer than the buffer size.

* bpo-32410: Implement "loop.sock_sendfile" for asyncio event loop.

* bpo-22908: Added seek and tell to the ZipExtFile class. This only
  works if the file object used to open the zipfile is seekable.

* bpo-32373: Add socket.getblocking() method.

* bpo-32248: Add "importlib.resources" and
  "importlib.abc.ResourceReader" as the unified API for reading
  resources contained within packages.  Loaders wishing to support
  resource reading must implement the "get_resource_reader()" method.
  File-based and zipimport-based loaders both implement these APIs.
  "importlib.abc.ResourceLoader" is deprecated in favor of these new
  APIs.

* bpo-32320: collections.namedtuple() now supports default values.

* bpo-29302: Add contextlib.AsyncExitStack. Patch by Alexander Mohr
  and Ilya Kulakov.

* bpo-31961: *Removed in Python 3.7.0b2.* The *args* argument of
  subprocess.Popen can now be a *path-like object*. If *args* is given
  as a sequence, it’s first element can now be a *path-like object* as
  well.

* bpo-31900: The "locale.localeconv()" function now sets temporarily
  the "LC_CTYPE" locale to the "LC_NUMERIC" locale to decode
  "decimal_point" and "thousands_sep" byte strings if they are non-
  ASCII or longer than 1 byte, and the "LC_NUMERIC" locale is
  different than the "LC_CTYPE" locale. This temporary change affects
  other threads. Same change for the "str.format()" method when
  formatting a number ("int", "float", "float" and subclasses) with
  the "n" type (ex: "'{:n}'.format(1234)").

* bpo-31853: Use super().method instead of socket.method in SSLSocket.
  They were there most likely for legacy reasons.

* bpo-31399: The ssl module now uses OpenSSL’s
  X509_VERIFY_PARAM_set1_host() and X509_VERIFY_PARAM_set1_ip() API to
  verify hostname and IP addresses. Subject common name fallback can
  be disabled with SSLContext.hostname_checks_common_name.

* bpo-14976: Add a queue.SimpleQueue class, an unbounded FIFO queue
  with a reentrant C implementation of put().


Documentation
-------------

* bpo-32724: Add references to some commands in the documentation of
  Pdb. Patch by Stéphane Wirtel

* bpo-32649: Complete the C API documentation, profiling and tracing
  part with the newly added per-opcode events.

* bpo-17799: Explain real behaviour of sys.settrace and sys.setprofile
  and their C-API counterparts regarding which type of events are
  received in each function. Patch by Pablo Galindo Salgado.


Tests
-----

* bpo-32721: Fix test_hashlib to not fail if the _md5 module is not
  built.

* bpo-28414: Add test cases for IDNA 2003 and 2008 host names. IDNA
  2003 internationalized host names are working since bpo-31399 has
  landed. IDNA 2008 are still broken.

* bpo-32604: Add a new “_xxsubinterpreters” extension module that
  exposes the existing subinterpreter C-API and a new cross-
  interpreter data sharing mechanism. The module is primarily intended
  for more thorough testing of the existing subinterpreter support.
  Note that the _xxsubinterpreters module has been removed in
  3.7.0rc1.

* bpo-32602: Add test certs and test for ECDSA cert and EC/RSA dual
  mode.

* bpo-32549: On Travis CI, Python now Compiles and uses a local copy
  of OpenSSL 1.1.0g for testing.


Build
-----

* bpo-32635: Fix segfault of the crypt module when libxcrypt is
  provided instead of libcrypt at the system.

* bpo-32598: Use autoconf to detect OpenSSL libs, headers and
  supported features. The ax_check_openssl M4 macro uses pkg-config to
  locate OpenSSL and falls back to manual search.

* bpo-32593: Drop support of FreeBSD 9 and older.

* bpo-29708: If the "SOURCE_DATE_EPOCH" environment variable is set,
  "py_compile" will always create hash-based ".pyc" files.


Windows
-------

* bpo-32588: Create standalone _distutils_findvs module and add
  missing _queue module to installer.

* bpo-29911: Ensure separate Modify and Uninstall buttons are
  displayed.

* bpo-32507: Use app-local UCRT install rather than the proper update
  for old versions of Windows.


macOS
-----

* bpo-32726: Provide an additional, more modern macOS installer
  variant that supports macOS 10.9+ systems in 64-bit mode only.
  Upgrade the supplied third-party libraries to OpenSSL 1.1.0g and to
  SQLite 3.22.0.  The 10.9+ installer now links with and supplies its
  own copy of Tcl/Tk 8.6.

* bpo-28440: No longer add /Library/Python/3.x/site-packages to
  sys.path for macOS framework builds to avoid future conflicts.


C API
-----

* bpo-32681: Fix uninitialized variable ‘res’ in the C implementation
  of os.dup2. Patch by Stéphane Wirtel

* bpo-10381: Add C API access to the "datetime.timezone" constructor
  and "datetime.timzone.UTC" singleton.


Python 3.7.0 alpha 4
====================

*Release date: 2018-01-08*


Core and Builtins
-----------------

* bpo-31975: The default warning filter list now starts with a
  “default::DeprecationWarning:__main__” entry, so deprecation
  warnings are once again shown by default in single-file scripts and
  at the interactive prompt.

* bpo-32226: "__class_getitem__" is now an automatic class method.

* bpo-32399: Add AIX uuid library support for RFC4122 using
  uuid_create() in libc.a

* bpo-32390: Fix the compilation failure on AIX after the f_fsid field
  has been added to the object returned by os.statvfs() (bpo-32143).
  Original patch by Michael Felt.

* bpo-32379: Make MRO computation faster when a class inherits from a
  single base.

* bpo-32259: The error message of a TypeError raised when unpack non-
  iterable is now more specific.

* bpo-27169: The "__debug__" constant is now optimized out at compile
  time. This fixes also bpo-22091.

* bpo-32329: The "-R" option now turns on hash randomization when the
  "PYTHONHASHSEED" environment variable is set to "0". Previously, the
  option was ignored. Moreover, "sys.flags.hash_randomization" is now
  properly set to 0 when hash randomization is turned off by
  "PYTHONHASHSEED=0".

* bpo-30416: The optimizer is now protected from spending much time
  doing complex calculations and consuming much memory for creating
  large constants in constant folding. Increased limits for constants
  that can be produced in constant folding.

* bpo-32282: Fix an unnecessary ifdef in the include of
  VersionHelpers.h in socketmodule on Windows.

* bpo-30579: Implement TracebackType.__new__ to allow Python-level
  creation of traceback objects, and make TracebackType.tb_next
  mutable.

* bpo-32260: Don’t byte swap the input keys to the SipHash algorithm
  on big-endian platforms. This should ensure siphash gives consistent
  results across platforms.

* bpo-31506: Improve the error message logic for object.__new__ and
  object.__init__. Patch by Sanyam Khurana.

* bpo-20361: "-b" and "-bb" now inject "'default::BytesWarning'" and
  "error::BytesWarning" entries into "sys.warnoptions", ensuring that
  they take precedence over any other warning filters configured via
  the "-W" option or the "PYTHONWARNINGS" environment variable.

* bpo-32230: "-X dev" now injects a "'default'" entry into
  sys.warnoptions, ensuring that it behaves identically to actually
  passing "-Wdefault" at the command line.

* bpo-29240: Add a new UTF-8 mode: implementation of the **PEP 540**.

* bpo-32226: **PEP 560**: Add support for "__mro_entries__" and
  "__class_getitem__". Implemented by Ivan Levkivskyi.

* bpo-32225: **PEP 562**: Add support for module "__getattr__" and
  "__dir__". Implemented by Ivan Levkivskyi.

* bpo-31901: The "atexit" module now has its callback stored per
  interpreter.

* bpo-31650: Implement **PEP 552** (Deterministic pycs). Python now
  supports invalidating bytecode cache files bashed on a source
  content hash rather than source last-modified time.

* bpo-29469: Move constant folding from bytecode layer to AST layer.
  Original patch by Eugene Toder.


Library
-------

* bpo-32506: Now that dict is defined as keeping insertion order, drop
  OrderedDict and just use plain dict.

* bpo-32279: Add params to dataclasses.make_dataclasses(): init, repr,
  eq, order, hash, and frozen.  Pass them through to dataclass().

* bpo-32278: Make type information optional on
  dataclasses.make_dataclass(). If omitted, the string ‘typing.Any’ is
  used.

* bpo-32499: Add dataclasses.is_dataclass(obj), which returns True if
  obj is a dataclass or an instance of one.

* bpo-32468: Improve frame repr() to mention filename, code name and
  current line number.

* bpo-23749: asyncio: Implement loop.start_tls()

* bpo-32441: Return the new file descriptor (i.e., the second
  argument) from "os.dup2". Previously, "None" was always returned.

* bpo-32422: "functools.lru_cache" uses less memory (3 words for each
  cached key) and takes about 1/3 time for cyclic GC.

* bpo-31721: Prevent Python crash from happening when
  Future._log_traceback is set to True manually.  Now it can only be
  set to False, or a ValueError is raised.

* bpo-32415: asyncio: Add Task.get_loop() and Future.get_loop()

* bpo-26133: Don’t unsubscribe signals in asyncio UNIX event loop on
  interpreter shutdown.

* bpo-32363: Make asyncio.Task.set_exception() and set_result() raise
  NotImplementedError. Task._step() and Future.__await__() raise
  proper exceptions when they are in an invalid state, instead of
  raising an AssertionError.

* bpo-32357: Optimize asyncio.iscoroutine() and loop.create_task() for
  non-native coroutines (e.g. async/await compiled with Cython).
  ‘loop.create_task(python_coroutine)’ used to be 20% faster than
  ‘loop.create_task(cython_coroutine)’.  Now, the latter is as fast.

* bpo-32356: asyncio.transport.resume_reading() and pause_reading()
  are now idempotent. New transport.is_reading() method is added.

* bpo-32355: Optimize asyncio.gather(); now up to 15% faster.

* bpo-32351: Use fastpath in asyncio.sleep if delay<0 (2x boost)

* bpo-32348: Optimize asyncio.Future schedule/add/remove callback.
  The optimization shows 3-6% performance improvements of async/await
  code.

* bpo-32331: Fix socket.settimeout() and socket.setblocking() to keep
  socket.type as is. Fix socket.socket() constructor to reset any bit
  flags applied to socket’s type.  This change only affects OSes that
  have SOCK_NONBLOCK and/or SOCK_CLOEXEC.

* bpo-32248: Add "importlib.abc.ResourceReader" as an ABC for loaders
  to provide a unified API for reading resources contained within
  packages. Also add "importlib.resources" as the port of
  "importlib_resources".

* bpo-32311: Implement asyncio.create_task(coro) shortcut

* bpo-32327: Convert asyncio functions that were documented as
  coroutines to coroutines. Affected functions: loop.sock_sendall,
  loop.sock_recv, loop.sock_accept, loop.getaddrinfo,
  loop.getnameinfo.

* bpo-32323: "urllib.parse.urlsplit()" does not convert zone-id
  (scope) to lower case for scoped IPv6 addresses in hostnames now.

* bpo-32302: Fix bdist_wininst of distutils for CRT v142: it binary
  compatible with CRT v140.

* bpo-29711: Fix "stop_serving" in asyncio proactor loop kill all
  listening servers

* bpo-32308: "re.sub()" now replaces empty matches adjacent to a
  previous non-empty match.

* bpo-29970: Abort asyncio SSLProtocol connection if handshake not
  complete within 10s

* bpo-32314: Implement asyncio.run().

* bpo-17852: Revert incorrect fix based on misunderstanding of
  _Py_PyAtExit() semantics.

* bpo-32296: Implement asyncio._get_running_loop() and
  get_event_loop() in C. This makes them 4x faster.

* bpo-32250: Implement "asyncio.current_task()" and
  "asyncio.all_tasks()". Add helpers intended to be used by
  alternative task implementations: "asyncio._register_task",
  "asyncio._enter_task", "asyncio._leave_task" and
  "asyncio._unregister_task". Deprecate "asyncio.Task.current_task()"
  and "asyncio.Task.all_tasks()".

* bpo-32255: A single empty field is now always quoted when written
  into a CSV file. This allows to distinguish an empty row from a row
  consisting of a single empty field. Patch by Licht Takeuchi.

* bpo-32277: Raise "NotImplementedError" instead of "SystemError" on
  platforms where "chmod(..., follow_symlinks=False)" is not
  supported. Patch by Anthony Sottile.

* bpo-30050: New argument warn_on_full_buffer to signal.set_wakeup_fd
  lets you control whether Python prints a warning on stderr when the
  wakeup fd buffer overflows.

* bpo-29137: The "fpectl" library has been removed. It was never
  enabled by default, never worked correctly on x86-64, and it changed
  the Python ABI in ways that caused unexpected breakage of C
  extensions.

* bpo-32273: Move asyncio.test_utils to test.test_asyncio.

* bpo-32272: Remove asyncio.async() function.

* bpo-32269: Add asyncio.get_running_loop() function.

* bpo-32265: All class and static methods of builtin types now are
  correctly classified by inspect.classify_class_attrs() and grouped
  in pydoc ouput. Added types.ClassMethodDescriptorType for unbound
  class methods of builtin types.

* bpo-32253: Deprecate "yield from lock", "await lock", "with (yield
  from lock)" and "with await lock" for asyncio synchronization
  primitives.

* bpo-22589: Changed MIME type of .bmp from ‘image/x-ms-bmp’ to
  ‘image/bmp’

* bpo-32193: Convert asyncio to use *async/await* syntax. Old styled
  "yield from" is still supported too.

* bpo-32206: Add support to run modules with pdb

* bpo-32227: "functools.singledispatch" now supports registering
  implementations using type annotations.

* bpo-15873: Added new alternate constructors
  "datetime.datetime.fromisoformat()", "datetime.time.fromisoformat()"
  and "datetime.date.fromisoformat()" as the inverse operation of each
  classes’s respective "isoformat" methods.

* bpo-32199: The getnode() ip getter now uses ‘ip link’ instead of ‘ip
  link list’.

* bpo-32143: os.statvfs() includes the f_fsid field from statvfs(2)

* bpo-26439: Fix ctypes.util.find_library() for AIX by implementing
  ctypes._aix.find_library() Patch by: Michael Felt

* bpo-31993: The pickler now uses less memory when serializing large
  bytes and str objects into a file.  Pickles created with protocol 4
  will require less memory for unpickling large bytes and str objects.

* bpo-27456: Ensure TCP_NODELAY is set on Linux. Tests by Victor
  Stinner.

* bpo-31778: ast.literal_eval() is now more strict. Addition and
  subtraction of arbitrary numbers no longer allowed.

* bpo-31802: Importing native path module ("posixpath", "ntpath") now
  works even if the "os" module still is not imported.

* bpo-30241: Add contextlib.AbstractAsyncContextManager. Patch by
  Jelle Zijlstra.

* bpo-31699: Fix deadlocks in "concurrent.futures.ProcessPoolExecutor"
  when task arguments or results cause pickling or unpickling errors.
  This should make sure that calls to the "ProcessPoolExecutor" API
  always eventually return.

* bpo-15216: "TextIOWrapper.reconfigure()" supports changing
  *encoding*, *errors*, and *newline*.


Documentation
-------------

* bpo-32418: Add get_loop() method to Server and AbstractServer
  classes.


Tests
-----

* bpo-32252: Fix faulthandler_suppress_crash_report() used to prevent
  core dump files when testing crashes. getrlimit() returns zero on
  success.

* bpo-32002: Adjust C locale coercion testing for the empty locale and
  POSIX locale cases to more readily adjust to platform dependent
  behaviour.


Windows
-------

* bpo-19764: Implement support for "subprocess.Popen(close_fds=True)"
  on Windows. Patch by Segev Finer.


Tools/Demos
-----------

* bpo-24960: 2to3 and lib2to3 can now read pickled grammar files using
  pkgutil.get_data() rather than probing the filesystem. This lets
  2to3 and lib2to3 work when run from a zipfile.


C API
-----

* bpo-32030: Py_Initialize() doesn’t reset the memory allocators to
  default if the "PYTHONMALLOC" environment variable is not set.

* bpo-29084: Undocumented C API for OrderedDict has been excluded from
  the limited C API. It was added by mistake and actually never worked
  in the limited C API.

* bpo-32264: Moved the pygetopt.h header into internal/, since it has
  no public APIs.

* bpo-32241: "Py_SetProgramName()" and "Py_SetPythonHome()" now take
  the "const wchar *" arguments instead of "wchar *".


Python 3.7.0 alpha 3
====================

*Release date: 2017-12-05*


Core and Builtins
-----------------

* bpo-32176: co_flags.CO_NOFREE is now always set correctly by the
  code object constructor based on freevars and cellvars, rather than
  needing to be set correctly by the caller. This ensures it will be
  cleared automatically when additional cell references are injected
  into a modified code object and function.

* bpo-10544: Yield expressions are now deprecated in comprehensions
  and generator expressions. They are still permitted in the
  definition of the outermost iterable, as that is evaluated directly
  in the enclosing scope.

* bpo-32137: The repr of deeply nested dict now raises a
  RecursionError instead of crashing due to a stack overflow.

* bpo-32096: Revert memory allocator changes in the C API: move
  structures back from _PyRuntime to Objects/obmalloc.c. The memory
  allocators are once again initialized statically, and so
  PyMem_RawMalloc() and Py_DecodeLocale() can be called before
  _PyRuntime_Initialize().

* bpo-32043: Add a new “developer mode”: new “-X dev” command line
  option to enable debug checks at runtime.

* bpo-32023: SyntaxError is now correctly raised when a generator
  expression without parenthesis is used instead of an inheritance
  list in a class definition. The duplication of the parentheses can
  be omitted only on calls.

* bpo-32012: SyntaxError is now correctly raised when a generator
  expression without parenthesis is passed as an argument, but
  followed by a trailing comma. A generator expression always needs to
  be directly inside a set of parentheses and cannot have a comma on
  either side.

* bpo-28180: A new internal "_Py_SetLocaleFromEnv(category)" helper
  function has been added in order to improve the consistency of
  behaviour across different "libc" implementations (e.g. Android
  doesn’t support setting the locale from the environment by default).

* bpo-31949: Fixed several issues in printing tracebacks
  (PyTraceBack_Print()). Setting sys.tracebacklimit to 0 or less now
  suppresses printing tracebacks. Setting sys.tracebacklimit to None
  now causes using the default limit. Setting sys.tracebacklimit to an
  integer larger than LONG_MAX now means using the limit LONG_MAX
  rather than the default limit. Fixed integer overflows in the case
  of more than "2**31" traceback items on Windows. Fixed output errors
  handling.

* bpo-30696: Fix the interactive interpreter looping endlessly when no
  memory.

* bpo-20047: Bytearray methods partition() and rpartition() now accept
  only bytes-like objects as separator, as documented.  In particular
  they now raise TypeError rather of returning a bogus result when an
  integer is passed as a separator.

* bpo-21720: BytesWarning no longer emitted when the *fromlist*
  argument of "__import__()" or the "__all__" attribute of the module
  contain bytes instances.

* bpo-31845: Environment variables are once more read correctly at
  interpreter startup.

* bpo-28936: Ensure that lexically first syntax error involving a
  parameter and "global" or "nonlocal" is detected first at a given
  scope. Patch by Ivan Levkivskyi.

* bpo-31825: Fixed OverflowError in the ‘unicode-escape’ codec and in
  codecs.escape_decode() when decode an escaped non-ascii byte.

* bpo-31618: The per-frame tracing logic added in 3.7a1 has been
  altered so that "frame->f_lineno" is updated before either ""line""
  or ""opcode"" events are emitted. Previously, opcode events were
  emitted first, and therefore would occasionally see stale line
  numbers on the frame. The behavior of this feature has changed
  slightly as a result: when both "f_trace_lines" and
  "f_trace_opcodes" are enabled, line events now occur first.

* bpo-28603: Print the full context/cause chain of exceptions on
  interpreter exit, even if an exception in the chain is unhashable or
  compares equal to later ones. Patch by Zane Bitter.

* bpo-31786: Fix timeout rounding in the select module to round
  correctly negative timeouts between -1.0 and 0.0. The functions now
  block waiting for events as expected. Previously, the call was
  incorrectly non-blocking. Patch by Pablo Galindo.

* bpo-31781: Prevent crashes when calling methods of an uninitialized
  "zipimport.zipimporter" object. Patch by Oren Milman.

* bpo-30399: Standard repr() of BaseException with a single argument
  no longer contains redundant trailing comma.

* bpo-31626: Fixed a bug in debug memory allocator.  There was a write
  to freed memory after shrinking a memory block.

* bpo-30817: "PyErr_PrintEx()" clears now the ignored exception that
  may be raised by "_PySys_SetObjectId()", for example when no memory.


Library
-------

* bpo-28556: Two minor fixes for "typing" module: allow shallow
  copying instances of generic classes, improve interaction of
  "__init_subclass__" with generics. Original PRs by Ivan Levkivskyi.

* bpo-32214: PEP 557, Data Classes. Provides a decorator which adds
  boilerplate methods to classes which use type annotations so specify
  fields.

* bpo-27240: The header folding algorithm for the new email policies
  has been rewritten, which also fixes bpo-30788, bpo-31831, and
  bpo-32182.  In particular, RFC2231 folding is now done correctly.

* bpo-32186: io.FileIO.readall() and io.FileIO.read() now release the
  GIL when getting the file size. Fixed hang of all threads with
  inaccessible NFS server. Patch by Nir Soffer.

* bpo-32101: Add "sys.flags.dev_mode" flag

* bpo-32154: The "asyncio.windows_utils.socketpair()" function has
  been removed: use directly "socket.socketpair()" which is available
  on all platforms since Python 3.5 (before, it wasn’t available on
  Windows). "asyncio.windows_utils.socketpair()" was just an alias to
  "socket.socketpair" on Python 3.5 and newer.

* bpo-32089: warnings: In development (-X dev) and debug mode (pydebug
  build), use the “default” action for ResourceWarning, rather than
  the “always” action, in the default warnings filters.

* bpo-32107: "uuid.getnode()" now preferentially returns universally
  administered MAC addresses if available, over locally administered
  MAC addresses.  This makes a better guarantee for global uniqueness
  of UUIDs returned from "uuid.uuid1()".  If only locally administered
  MAC addresses are available, the first such one found is returned.

* bpo-23033: Wildcard is now supported in hostname when it is one and
  only character in the left most segment of hostname in second
  argument of "ssl.match_hostname()".  Patch by Mandeep Singh.

* bpo-12239: Make "msilib.SummaryInformation.GetProperty()" return
  "None" when the value of property is "VT_EMPTY".  Initial patch by
  Mark Mc Mahon.

* bpo-28334: Use "os.path.expanduser()" to find the "~/.netrc" file in
  "netrc.netrc".  If it does not exist, "FileNotFoundError" is raised.
  Patch by Dimitri Merejkowsky.

* bpo-32121: Made "tracemalloc.Traceback" behave more like the
  traceback module, sorting the frames from oldest to most recent.
  "Traceback.format()" now accepts negative *limit*, truncating the
  result to the "abs(limit)" oldest frames. To get the old behaviour,
  one can use the new *most_recent_first* argument to
  "Traceback.format()". (Patch by Jesse Bakker.)

* bpo-31325: Fix wrong usage of "collections.namedtuple()" in the
  "RobotFileParser.parse()" method. Initial patch by Robin Wellner.

* bpo-12382: "msilib.OpenDatabase()" now raises a better exception
  message when it couldn’t open or create an MSI file.  Initial patch
  by William Tisäter.

* bpo-19610: "setup()" now warns about invalid types for some fields.
  The "distutils.dist.Distribution" class now warns when
  "classifiers", "keywords" and "platforms" fields are not specified
  as a list or a string.

* bpo-32071: Added the "-k" command-line option to "python -m
  unittest" to run only tests that match the given pattern(s).

* bpo-10049: Added *nullcontext* no-op context manager to contextlib.
  This provides a simpler and faster alternative to ExitStack() when
  handling optional context managers.

* bpo-28684: The new test.support.skip_unless_bind_unix_socket()
  decorator is used here to skip asyncio tests that fail because the
  platform lacks a functional bind() function for unix domain sockets
  (as it is the case for non root users on the recent Android versions
  that run now SELinux in enforcing mode).

* bpo-32110: "codecs.StreamReader.read(n)" now returns not more than
  *n* characters/bytes for non-negative *n*. This makes it compatible
  with "read()" methods of other file-like objects.

* bpo-27535: The warnings module doesn’t leak memory anymore in the
  hidden warnings registry for the “ignore” action of warnings
  filters. warn_explicit() function doesn’t add the warning key to the
  registry anymore for the “ignore” action.

* bpo-32088: warnings:  When Python is build is debug mode
  ("Py_DEBUG"), "DeprecationWarning", "PendingDeprecationWarning" and
  "ImportWarning" warnings are now displayed by default.

* bpo-1647489: Fixed searching regular expression patterns that could
  match an empty string. Non-empty string can now be correctly found
  after matching an empty string.

* bpo-25054: Added support of splitting on a pattern that could match
  an empty string.

* bpo-32072: Fixed issues with binary plists: Fixed saving bytearrays.
  Identical objects will be saved only once. Equal references will be
  load as identical objects. Added support for saving and loading
  recursive data structures.

* bpo-32069: Drop legacy SSL transport from asyncio, ssl.MemoryBIO is
  always used anyway.

* bpo-32066: asyncio: Support pathlib.Path in create_unix_connection;
  sock arg should be optional

* bpo-32046: Updates 2to3 to convert from operator.isCallable(obj) to
  callable(obj). Patch by Dong-hee Na.

* bpo-32018: inspect.signature should follow **PEP 8**, if the
  parameter has an annotation and a default value. Patch by Dong-hee
  Na.

* bpo-32025: Add time.thread_time() and time.thread_time_ns()

* bpo-32037: Integers that fit in a signed 32-bit integer will be now
  pickled with protocol 0 using the INT opcode.  This will decrease
  the size of a pickle, speed up pickling and unpickling, and make
  these integers be unpickled as int instances in Python 2.

* bpo-32034: Make asyncio.IncompleteReadError and LimitOverrunError
  pickleable.

* bpo-32015: Fixed the looping of asyncio in the case of reconnection
  the socket during waiting async read/write from/to the socket.

* bpo-32011: Restored support of loading marshal files with the
  TYPE_INT64 code. These files can be produced in Python 2.7.

* bpo-28369: Enhance add_reader/writer check that socket is not used
  by some transport. Before, only cases when add_reader/writer were
  called with an int FD were supported.  Now the check is implemented
  correctly for all file-like objects.

* bpo-31976: Fix race condition when flushing a file is slow, which
  can cause a segfault if closing the file from another thread.

* bpo-31985: Formally deprecated aifc.openfp, sunau.openfp, and
  wave.openfp. Since change 7bc817d5ba917528e8bd07ec461c635291e7b06a
  in 1993, openfp in each of the three modules had been pointing to
  that module’s open function as a matter of backwards compatibility,
  though it had been both untested and undocumented.

* bpo-21862: cProfile command line now accepts "-m module_name" as an
  alternative to script path. Patch by Sanyam Khurana.

* bpo-31970: Reduce performance overhead of asyncio debug mode.

* bpo-31843: *database* argument of sqlite3.connect() now accepts a
  *path-like object*, instead of just a string.

* bpo-31945: Add Configurable *blocksize* to "HTTPConnection" and
  "HTTPSConnection" for improved upload throughput.  Patch by Nir
  Soffer.

* bpo-31943: Add a "cancelled()" method to "asyncio.Handle".  Patch by
  Marat Sharafutdinov.

* bpo-9678: Fixed determining the MAC address in the uuid module:
  Using ifconfig on NetBSD and OpenBSD. Using arp on Linux, FreeBSD,
  NetBSD and OpenBSD. Based on patch by Takayuki Shimizukawa.

* bpo-30057: Fix potential missed signal in signal.signal().

* bpo-31933: Fix Blake2 params leaf_size and node_offset on big endian
  platforms. Patch by Jack O’Connor.

* bpo-21423: Add an initializer argument to
  {Process,Thread}PoolExecutor

* bpo-31927: Fixed compilation of the socket module on NetBSD 8.
  Fixed assertion failure or reading arbitrary data when parse a
  AF_BLUETOOTH address on NetBSD and DragonFly BSD.

* bpo-27666: Fixed stack corruption in curses.box() and
  curses.ungetmouse() when the size of types chtype or mmask_t is less
  than the size of C long. curses.box() now accepts characters as
  arguments.  Based on patch by Steve Fink.

* bpo-31917: Add 3 new clock identifiers: "time.CLOCK_BOOTTIME",
  "time.CLOCK_PROF" and "time.CLOCK_UPTIME".

* bpo-31897: plistlib now catches more errors when read binary plists
  and raises InvalidFileException instead of unexpected exceptions.

* bpo-25720: Fix the method for checking pad state of curses WINDOW.
  Patch by Masayuki Yamamoto.

* bpo-31893: Fixed the layout of the kqueue_event structure on OpenBSD
  and NetBSD. Fixed the comparison of the kqueue_event objects.

* bpo-31891: Fixed building the curses module on NetBSD.

* bpo-31884: added required constants to subprocess module for setting
  priority on windows

* bpo-28281: Remove year (1-9999) limits on the Calendar.weekday()
  function. Patch by Mark Gollahon.

* bpo-31702: crypt.mksalt() now allows to specify the number of rounds
  for SHA-256 and SHA-512 hashing.

* bpo-30639: "inspect.getfile()" no longer computes the repr of
  unknown objects to display in an error message, to protect against
  badly behaved custom reprs.

* bpo-30768: Fix the pthread+semaphore implementation of
  PyThread_acquire_lock_timed() when called with timeout > 0 and
  intr_flag=0: recompute the timeout if sem_timedwait() is interrupted
  by a signal (EINTR). See also the **PEP 475**.

* bpo-31854: Add "mmap.ACCESS_DEFAULT" constant.

* bpo-31834: Use optimized code for BLAKE2 only with SSSE3+. The pure
  SSE2 implementation is slower than the pure C reference
  implementation.

* bpo-28292: Calendar.itermonthdates() will now consistently raise an
  exception when a date falls outside of the 0001-01-01 through
  9999-12-31 range.  To support applications that cannot tolerate such
  exceptions, the new methods itermonthdays3() and itermonthdays4()
  are added.  The new methods return tuples and are not restricted by
  the range supported by datetime.date.

* bpo-28564: The shutil.rmtree() function has been sped up to 20–40%.
  This was done using the os.scandir() function.

* bpo-28416: Instances of pickle.Pickler subclass with the
  persistent_id() method and pickle.Unpickler subclass with the
  persistent_load() method no longer create reference cycles.

* bpo-31653: Don’t release the GIL if we can acquire a multiprocessing
  semaphore immediately.

* bpo-28326: Fix multiprocessing.Process when stdout and/or stderr is
  closed or None.

* bpo-20825: Add "subnet_of" and "superset_of" containment tests to
  "ipaddress.IPv6Network" and "ipaddress.IPv4Network". Patch by Michel
  Albert and Cheryl Sabella.

* bpo-31827: Remove the os.stat_float_times() function. It was
  introduced in Python 2.3 for backward compatibility with Python 2.2,
  and was deprecated since Python 3.1.

* bpo-31756: Add a "subprocess.Popen(text=False)" keyword argument to
  "subprocess" functions to be more explicit about when the library
  should attempt to decode outputs into text. Patch by Andrew Clegg.

* bpo-31819: Add AbstractEventLoop.sock_recv_into().

* bpo-31457: If nested log adapters are used, the inner "process()"
  methods are no longer omitted.

* bpo-31457: The "manager" property on LoggerAdapter objects is now
  properly settable.

* bpo-31806: Fix timeout rounding in time.sleep(),
  threading.Lock.acquire() and socket.socket.settimeout() to round
  correctly negative timeouts between -1.0 and 0.0. The functions now
  block waiting for events as expected. Previously, the call was
  incorrectly non-blocking. Patch by Pablo Galindo.

* bpo-31803: time.clock() and time.get_clock_info(‘clock’) now emit a
  DeprecationWarning warning.

* bpo-31800: Extended support for parsing UTC offsets. strptime ‘%z’
  can now parse the output generated by datetime.isoformat, including
  seconds and microseconds.

* bpo-28603: traceback: Fix a TypeError that occurred during printing
  of exception tracebacks when either the current exception or an
  exception in its context/cause chain is unhashable. Patch by Zane
  Bitter.

* bpo-30541: Add new function to seal a mock and prevent the
  automatically creation of child mocks. Patch by Mario Corchero.

* bpo-31784: Implement the **PEP 564**, add new 6 new functions with
  nanosecond resolution to the "time" module: "clock_gettime_ns()",
  "clock_settime_ns()", "monotonic_ns()", "perf_counter_ns()",
  "process_time_ns()", "time_ns()".

* bpo-30143: 2to3 now generates a code that uses abstract collection
  classes from collections.abc rather than collections.

* bpo-31770: Prevent a crash when calling the "__init__()" method of a
  "sqlite3.Cursor" object more than once. Patch by Oren Milman.

* bpo-31764: Prevent a crash in "sqlite3.Cursor.close()" in case the
  "Cursor" object is uninitialized. Patch by Oren Milman.

* bpo-31752: Fix possible crash in timedelta constructor called with
  custom integers.

* bpo-31620: an empty asyncio.Queue now doesn’t leak memory when
  queue.get pollers timeout

* bpo-31690: Allow the flags re.ASCII, re.LOCALE, and re.UNICODE to be
  used as group flags for regular expressions.

* bpo-30349: FutureWarning is now emitted if a regular expression
  contains character set constructs that will change semantically in
  the future (nested sets and set operations).

* bpo-31664: Added support for the Blowfish hashing in the crypt
  module.

* bpo-31632: Fix method set_protocol() of class _SSLProtocolTransport
  in asyncio module. This method was previously modifying a wrong
  reference to the protocol.

* bpo-15037: Added a workaround for getkey() in curses for ncurses 5.7
  and earlier.

* bpo-31307: Allow use of bytes objects for arguments to
  "configparser.ConfigParser.read()". Patch by Vincent Michel.

* bpo-31334: Fix "poll.poll([timeout])" in the "select" module for
  arbitrary negative timeouts on all OSes where it can only be a non-
  negative integer or -1. Patch by Riccardo Coccioli.

* bpo-31310: multiprocessing’s semaphore tracker should be launched
  again if crashed.

* bpo-31308: Make multiprocessing’s forkserver process immune to
  Ctrl-C and other user interruptions. If it crashes, restart it when
  necessary.

* bpo-31245: Added support for AF_UNIX socket in asyncio
  "create_datagram_endpoint".

* bpo-30553: Add HTTP/2 status code 421 (Misdirected Request) to
  "http.HTTPStatus". Patch by Vitor Pereira.


Documentation
-------------

* bpo-32105: Added asyncio.BaseEventLoop.connect_accepted_socket
  versionadded marker.


Tests
-----

* bpo-31380: Skip test_httpservers test_undecodable_file on macOS:
  fails on APFS.

* bpo-31705: Skip test_socket.test_sha256() on Linux kernel older than
  4.5. The test fails with ENOKEY on kernel 3.10 (on ppc64le). A fix
  was merged into the kernel 4.5.

* bpo-32138: Skip on Android test_faulthandler tests that raise
  SIGSEGV and remove the test.support.requires_android_level
  decorator.

* bpo-32136: The runtime embedding tests have been split out from
  "Lib/test/test_capi.py" into a new "Lib/test/test_embed.py" file.

* bpo-28668: test.support.requires_multiprocessing_queue is removed.
  Skip tests with
  test.support.import_module(‘multiprocessing.synchronize’) instead
  when the semaphore implementation is broken or missing.

* bpo-32126: Skip test_get_event_loop_new_process in
  test.test_asyncio.test_events when sem_open() is not functional.

* bpo-31174: Fix test_tools.test_unparse: DirectoryTestCase now stores
  the names sample to always test the same files. It prevents false
  alarms when hunting reference leaks.


Build
-----

* bpo-28538: Revert the previous changes, the if_nameindex structure
  is defined by Unified Headers.

* bpo-28762: Revert the last commit, the F_LOCK macro is defined by
  Android Unified Headers.

* bpo-29040: Support building Android with Unified Headers. The first
  NDK release to support Unified Headers is android-ndk-r14.

* bpo-32059: "detect_modules()" in "setup.py" now also searches the
  sysroot paths when cross-compiling.

* bpo-31957: Fixes Windows SDK version detection when building for
  Windows.

* bpo-31609: Fixes quotes in PCbuild/clean.bat

* bpo-31934: Abort the build when building out of a not clean source
  tree.

* bpo-31926: Fixed Argument Clinic sometimes causing compilation
  errors when there was more than one function and/or method in a .c
  file with the same name.

* bpo-28791: Update Windows builds to use SQLite 3.21.0.

* bpo-28791: Update OS X installer to use SQLite 3.21.0.

* bpo-28643: Record profile-opt build progress with stamp files.

* bpo-31866: Finish removing support for AtheOS.


Windows
-------

* bpo-1102: Return "None" when "View.Fetch()" returns
  "ERROR_NO_MORE_ITEMS" instead of raising "MSIError". Initial patch
  by Anthony Tuininga.

* bpo-31944: Fixes Modify button in Apps and Features dialog.

* bpo-20486: Implement the "Database.Close()" method to help closing
  MSI database objects.

* bpo-31857: Make the behavior of USE_STACKCHECK deterministic in a
  multi-threaded environment.


macOS
-----

* bpo-31392: Update macOS installer to use OpenSSL 1.0.2m


IDLE
----

* bpo-32207: Improve tk event exception tracebacks in IDLE. When tk
  event handling is driven by IDLE’s run loop, a confusing and
  distracting queue.EMPTY traceback context is no longer added to tk
  event exception tracebacks.  The traceback is now the same as when
  event handling is driven by user code.  Patch based on a suggestion
  by Serhiy Storchaka.

* bpo-32164: Delete unused file idlelib/tabbedpages.py. Use of
  TabbedPageSet in configdialog was replaced by ttk.Notebook.

* bpo-32100: IDLE: Fix old and new bugs in pathbrowser; improve tests.
  Patch mostly by Cheryl Sabella.

* bpo-31858: IDLE – Restrict shell prompt manipulation to the shell.
  Editor and output windows only see an empty last prompt line.  This
  simplifies the code and fixes a minor bug when newline is inserted.
  Sys.ps1, if present, is read on Shell start-up, but is not set or
  changed.

* bpo-31860: The font sample in the IDLE configuration dialog is now
  editable. Changes persist while IDLE remains open

* bpo-31836: Test_code_module now passes if run after test_idle, which
  sets ps1. The code module uses sys.ps1 if present or sets it to ‘>>>
  ‘ if not. Test_code_module now properly tests both behaviors.  Ditto
  for ps2.

* bpo-28603: Fix a TypeError that caused a shell restart when printing
  a traceback that includes an exception that is unhashable. Patch by
  Zane Bitter.

* bpo-13802: Use non-Latin characters in the IDLE’s Font settings
  sample. Even if one selects a font that defines a limited subset of
  the unicode Basic Multilingual Plane, tcl/tk will use other fonts
  that define a character. The expanded example give users of non-
  Latin characters a better idea of what they might see in IDLE’s
  shell and editors. To make room for the expanded sample, frames on
  the Font tab are re-arranged.  The Font/Tabs help explains a bit
  about the additions.


Tools/Demos
-----------

* bpo-32159: Remove CVS and Subversion tools: remove svneol.py and
  treesync.py scripts. CPython migrated from CVS to Subversion, to
  Mercurial, and then to Git. CVS and Subversion are no longer used to
  develop CPython.

* bpo-30722: Make redemo work with Python 3.6 and newer versions.
  Also, remove the "LOCALE" option since it doesn’t work with string
  patterns in Python 3. Patch by Christoph Sarnowski.


C API
-----

* bpo-20891: Fix PyGILState_Ensure(). When PyGILState_Ensure() is
  called in a non-Python thread before PyEval_InitThreads(), only call
  PyEval_InitThreads() after calling PyThreadState_New() to fix a
  crash.

* bpo-32125: The "Py_UseClassExceptionsFlag" flag has been removed. It
  was deprecated and wasn’t used anymore since Python 2.0.

* bpo-25612: Move the current exception state from the frame object to
  the co-routine. This simplifies the interpreter and fixes a couple
  of obscure bugs caused by having swap exception state when entering
  or exiting a generator.

* bpo-23699: Add Py_RETURN_RICHCOMPARE macro to reduce boilerplate
  code in rich comparison functions.

* bpo-30697: The "PyExc_RecursionErrorInst" singleton is removed and
  "PyErr_NormalizeException()" does not use it anymore. This singleton
  is persistent and its members being never cleared may cause a
  segfault during finalization of the interpreter. See also bpo-22898.


Python 3.7.0 alpha 2
====================

*Release date: 2017-10-16*


Core and Builtins
-----------------

* bpo-31558: "gc.freeze()" is a new API that allows for moving all
  objects currently tracked by the garbage collector to a permanent
  generation, effectively removing them from future collection events.
  This can be used to protect those objects from having their
  PyGC_Head mutated. In effect, this enables great copy-on-write
  stability at fork().

* bpo-31642: Restored blocking “from package import module” by setting
  sys.modules[“package.module”] to None.

* bpo-31708: Allow use of asynchronous generator expressions in
  synchronous functions.

* bpo-31709: Drop support of asynchronous __aiter__.

* bpo-30404: The -u option now makes the stdout and stderr streams
  unbuffered rather than line-buffered.

* bpo-31619: Fixed a ValueError when convert a string with large
  number of underscores to integer with binary base.

* bpo-31602: Fix an assertion failure in "zipimporter.get_source()" in
  case of a bad "zlib.decompress()". Patch by Oren Milman.

* bpo-31592: Fixed an assertion failure in Python parser in case of a
  bad "unicodedata.normalize()". Patch by Oren Milman.

* bpo-31588: Raise a "TypeError" with a helpful error message when
  class creation fails due to a metaclass with a bad "__prepare__()"
  method. Patch by Oren Milman.

* bpo-31574: Importlib was instrumented with two dtrace probes to
  profile import timing.

* bpo-31566: Fix an assertion failure in "_warnings.warn()" in case of
  a bad "__name__" global. Patch by Oren Milman.

* bpo-31506: Improved the error message logic for object.__new__ and
  object.__init__.

* bpo-31505: Fix an assertion failure in "json", in case
  "_json.make_encoder()" received a bad "encoder()" argument. Patch by
  Oren Milman.

* bpo-31492: Fix assertion failures in case of failing to import from
  a module with a bad "__name__" attribute, and in case of failing to
  access an attribute of such a module. Patch by Oren Milman.

* bpo-31478: Fix an assertion failure in "_random.Random.seed()" in
  case the argument has a bad "__abs__()" method. Patch by Oren
  Milman.

* bpo-31336: Speed up class creation by 10-20% by reducing the
  overhead in the necessary special method lookups.  Patch by Stefan
  Behnel.

* bpo-31415: Add "-X importtime" option to show how long each import
  takes. It can be used to optimize application’s startup time.
  Support the "PYTHONPROFILEIMPORTTIME" as an equivalent way to enable
  this.

* bpo-31410: Optimized calling wrapper and classmethod descriptors.

* bpo-31353: **PEP 553** - Add a new built-in called "breakpoint()"
  which calls "sys.breakpointhook()".  By default this imports "pdb"
  and calls "pdb.set_trace()", but users may override
  "sys.breakpointhook()" to call whatever debugger they want.  The
  original value of the hook is saved in "sys.__breakpointhook__".

* bpo-17852: Maintain a list of open buffered files, flush them before
  exiting the interpreter.  Based on a patch from Armin Rigo.

* bpo-31315: Fix an assertion failure in imp.create_dynamic(), when
  spec.name is not a string. Patch by Oren Milman.

* bpo-31311: Fix a crash in the "__setstate__()" method of
  "ctypes._CData", in case of a bad "__dict__". Patch by Oren Milman.

* bpo-31293: Fix crashes in true division and multiplication of a
  timedelta object by a float with a bad as_integer_ratio() method.
  Patch by Oren Milman.

* bpo-31285: Fix an assertion failure in "warnings.warn_explicit",
  when the return value of the received loader’s get_source() has a
  bad splitlines() method. Patch by Oren Milman.

* bpo-30406: Make "async" and "await" proper keywords, as specified in
  **PEP 492**.


Library
-------

* bpo-30058: Fixed buffer overflow in select.kqueue.control().

* bpo-31672: "idpattern" in "string.Template" matched some non-ASCII
  characters. Now it uses "-i" regular expression local flag to avoid
  non-ASCII characters.

* bpo-31701: On Windows, faulthandler.enable() now ignores MSC and COM
  exceptions.

* bpo-31728: Prevent crashes in "_elementtree" due to unsafe cleanup
  of "Element.text" and "Element.tail". Patch by Oren Milman.

* bpo-31671: Now "re.compile()" converts passed RegexFlag to normal
  int object before compiling. bm_regex_compile benchmark shows 14%
  performance improvements.

* bpo-30397: The types of compiled regular objects and match objects
  are now exposed as "re.Pattern" and "re.Match".  This adds
  information in pydoc output for the re module.

* bpo-31675: Fixed memory leaks in Tkinter’s methods splitlist() and
  split() when pass a string larger than 2 GiB.

* bpo-31673: Fixed typo in the name of Tkinter’s method
  adderrorinfo().

* bpo-31648: Improvements to path predicates in ElementTree: Allow
  whitespace around predicate parts, i.e. “[a = ‘text’]” instead of
  requiring the less readable “[a=’text’]”. Add support for text
  comparison of the current node, like “[.=’text’]”. Patch by Stefan
  Behnel.

* bpo-30806: Fix the string representation of a netrc object.

* bpo-31638: Add optional argument "compressed" to
  "zipapp.create_archive", and add option "--compress" to the command
  line interface of "zipapp".

* bpo-25351: Avoid venv activate failures with undefined variables

* bpo-20519: Avoid ctypes use (if possible) and improve import time
  for uuid.

* bpo-28293: The regular expression cache is no longer completely
  dumped when it is full.

* bpo-31596: Added pthread_getcpuclockid() to the time module

* bpo-27494: Make 2to3 accept a trailing comma in generator
  expressions. For example, "set(x for x in [],)" is now allowed.

* bpo-30347: Stop crashes when concurrently iterate over
  itertools.groupby() iterators.

* bpo-30346: An iterator produced by itertools.groupby() iterator now
  becomes exhausted after advancing the groupby iterator.

* bpo-31556: Cancel asyncio.wait_for future faster if timeout <= 0

* bpo-31540: Allow passing a context object in
  "concurrent.futures.ProcessPoolExecutor" constructor. Also, free job
  resources in "concurrent.futures.ProcessPoolExecutor" earlier to
  improve memory usage when a worker waits for new jobs.

* bpo-31516: "threading.current_thread()" should not return a dummy
  thread at shutdown.

* bpo-31525: In the sqlite module, require the sqlite3_prepare_v2 API.
  Thus, the sqlite module now requires sqlite version at least 3.3.9.

* bpo-26510: argparse subparsers are now required by default.  This
  matches behaviour in Python 2. For optional subparsers, use the new
  parameter "add_subparsers(required=False)". Patch by Anthony
  Sottile. (As of 3.7.0rc1, the default was changed to not required as
  had been the case since Python 3.3.)

* bpo-27541: Reprs of subclasses of some collection and iterator
  classes ("bytearray", "array.array", "collections.deque",
  "collections.defaultdict", "itertools.count", "itertools.repeat")
  now contain actual type name insteads of hardcoded name of the base
  class.

* bpo-31351: python -m ensurepip now exits with non-zero exit code if
  pip bootstrapping has failed.

* bpo-31389: "pdb.set_trace()" now takes an optional keyword-only
  argument "header". If given, this is printed to the console just
  before debugging begins.


Documentation
-------------

* bpo-31537: Fix incorrect usage of "get_history_length" in readline
  documentation example code. Patch by Brad Smith.

* bpo-30085: The operator functions without double underscores are
  preferred for clarity. The one with underscores are only kept for
  back-compatibility.


Build
-----

* bpo-31696: Improve compiler version information in "sys.version"
  when Python is built with Clang.

* bpo-31625: Stop using ranlib on static libraries. Instead, we assume
  ar supports the ‘s’ flag.

* bpo-31624: Remove support for BSD/OS.

* bpo-22140: Prevent double substitution of prefix in python-
  config.sh.

* bpo-31569: Correct PCBuild/ case to PCbuild/ in build scripts and
  documentation.

* bpo-31536: Avoid wholesale rebuild after "make regen-all" if nothing
  changed.


IDLE
----

* bpo-31460: Simplify the API of IDLE’s Module Browser. Passing a
  widget instead of an flist with a root widget opens the option of
  creating a browser frame that is only part of a window.  Passing a
  full file name instead of pieces assumed to come from a .py file
  opens the possibility of browsing python files that do not end in
  .py.

* bpo-31649: IDLE - Make _htest, _utest parameters keyword only.

* bpo-31559: Remove test order dependence in idle_test.test_browser.

* bpo-31459: Rename IDLE’s module browser from Class Browser to Module
  Browser. The original module-level class and method browser became a
  module browser, with the addition of module-level functions, years
  ago. Nested classes and functions were added yesterday.  For back-
  compatibility, the virtual event <<open-class-browser>>, which
  appears on the Keys tab of the Settings dialog, is not changed.
  Patch by Cheryl Sabella.

* bpo-31500: Default fonts now are scaled on HiDPI displays.

* bpo-1612262: IDLE module browser now shows nested classes and
  functions. Original patches for code and tests by Guilherme Polo and
  Cheryl Sabella, respectively.


C API
-----

* bpo-28280: Make "PyMapping_Keys()", "PyMapping_Values()" and
  "PyMapping_Items()" always return a "list" (rather than a "list" or
  a "tuple"). Patch by Oren Milman.

* bpo-31532: Fix memory corruption due to allocator mix in getpath.c
  between Py_GetPath() and Py_SetPath()

* bpo-25658: Implement **PEP 539** for Thread Specific Storage (TSS)
  API: it is a new Thread Local Storage (TLS) API to CPython which
  would supersede use of the existing TLS API within the CPython
  interpreter, while deprecating the existing API. PEP written by Erik
  M. Bray, patch by Masayuki Yamamoto.


Python 3.7.0 alpha 1
====================

*Release date: 2017-09-19*


Security
--------

* bpo-29781: SSLObject.version() now correctly returns None when
  handshake over BIO has not been performed yet.

* bpo-29505: Add fuzz tests for float(str), int(str), unicode(str);
  for oss-fuzz.

* bpo-30947: Upgrade libexpat embedded copy from version 2.2.1 to
  2.2.3 to get security fixes.

* bpo-30730: Prevent environment variables injection in subprocess on
  Windows.  Prevent passing other environment variables and command
  arguments.

* bpo-30694: Upgrade expat copy from 2.2.0 to 2.2.1 to get fixes of
  multiple security vulnerabilities including: CVE-2017-9233 (External
  entity infinite loop DoS), CVE-2016-9063 (Integer overflow, re-fix),
  CVE-2016-0718 (Fix regression bugs from 2.2.0’s fix to
  CVE-2016-0718) and CVE-2012-0876 (Counter hash flooding with
  SipHash). Note: the CVE-2016-5300 (Use os-specific entropy sources
  like getrandom) doesn’t impact Python, since Python already gets
  entropy from the OS to set the expat secret using
  "XML_SetHashSalt()".

* bpo-30500: Fix urllib.parse.splithost() to correctly parse
  fragments. For example, "splithost('//127.0.0.1#@evil.com/')" now
  correctly returns the "127.0.0.1" host, instead of treating
  "@evil.com" as the host in an authentication ("login@host").

* bpo-29591: Update expat copy from 2.1.1 to 2.2.0 to get fixes of
  CVE-2016-0718 and CVE-2016-4472. See
  https://sourceforge.net/p/expat/bugs/537/ for more information.


Core and Builtins
-----------------

* bpo-31490: Fix an assertion failure in "ctypes" class definition, in
  case the class has an attribute whose name is specified in
  "_anonymous_" but not in "_fields_". Patch by Oren Milman.

* bpo-31471: Fix an assertion failure in "subprocess.Popen()" on
  Windows, in case the env argument has a bad keys() method. Patch by
  Oren Milman.

* bpo-31418: Fix an assertion failure in "PyErr_WriteUnraisable()" in
  case of an exception with a bad "__module__" attribute. Patch by
  Oren Milman.

* bpo-31416: Fix assertion failures in case of a bad warnings.filters
  or warnings.defaultaction. Patch by Oren Milman.

* bpo-28411: Change direct usage of PyInterpreterState.modules to
  PyImport_GetModuleDict(). Also introduce more uniformity in other
  code that deals with sys.modules. This helps reduce complications
  when working on sys.modules.

* bpo-28411: Switch to the abstract API when dealing with
  "PyInterpreterState.modules". This allows later support for all dict
  subclasses and other Mapping implementations.  Also add a
  "PyImport_GetModule()" function to reduce a bunch of duplicated
  code.

* bpo-31411: Raise a TypeError instead of SystemError in case
  warnings.onceregistry is not a dictionary. Patch by Oren Milman.

* bpo-31344: For finer control of tracing behaviour when testing the
  interpreter, two new frame attributes have been added to control the
  emission of particular trace events: "f_trace_lines" ("True" by
  default) to turn off per-line trace events; and "f_trace_opcodes"
  ("False" by default) to turn on per-opcode trace events.

* bpo-31373: Fix several possible instances of undefined behavior due
  to floating-point demotions.

* bpo-30465: Location information ("lineno" and "col_offset") in
  f-strings is now (mostly) correct.  This fixes tools like flake8
  from showing warnings on the wrong line (typically the first line of
  the file).

* bpo-30860: Consolidate CPython’s global runtime state under a single
  struct.  This improves discoverability of the runtime state.

* bpo-31347: Fix possible undefined behavior in
  _PyObject_FastCall_Prepend.

* bpo-31343: Include sys/sysmacros.h for major(), minor(), and
  makedev(). GNU C libray plans to remove the functions from
  sys/types.h.

* bpo-31291: Fix an assertion failure in
  "zipimport.zipimporter.get_data" on Windows, when the return value
  of "pathname.replace('/','\\')" isn’t a string. Patch by Oren
  Milman.

* bpo-31271: Fix an assertion failure in the write() method of
  "io.TextIOWrapper", when the encoder doesn’t return a bytes object.
  Patch by Oren Milman.

* bpo-31243: Fix a crash in some methods of "io.TextIOWrapper", when
  the decoder’s state is invalid. Patch by Oren Milman.

* bpo-30721: "print" now shows correct usage hint for using Python 2
  redirection syntax.  Patch by Sanyam Khurana.

* bpo-31070: Fix a race condition in importlib _get_module_lock().

* bpo-30747: Add a non-dummy implementation of _Py_atomic_store and
  _Py_atomic_load on MSVC.

* bpo-31095: Fix potential crash during GC caused by "tp_dealloc"
  which doesn’t call "PyObject_GC_UnTrack()".

* bpo-31071: Avoid masking original TypeError in call with * unpacking
  when other arguments are passed.

* bpo-30978: str.format_map() now passes key lookup exceptions
  through. Previously any exception was replaced with a KeyError
  exception.

* bpo-30808: Use _Py_atomic API for concurrency-sensitive signal
  state.

* bpo-30876: Relative import from unloaded package now reimports the
  package instead of failing with SystemError.  Relative import from
  non-package now fails with ImportError rather than SystemError.

* bpo-30703: Improve signal delivery. Avoid using Py_AddPendingCall
  from signal handler, to avoid calling signal-unsafe functions. The
  tests I’m adding here fail without the rest of the patch, on Linux
  and OS X. This means our signal delivery logic had defects (some
  signals could be lost).

* bpo-30765: Avoid blocking in pthread_mutex_lock() when
  PyThread_acquire_lock() is asked not to block.

* bpo-31161: Make sure the ‘Missing parentheses’ syntax error message
  is only applied to SyntaxError, not to subclasses. Patch by Martijn
  Pieters.

* bpo-30814: Fixed a race condition when import a submodule from a
  package.

* bpo-30736: The internal unicodedata database has been upgraded to
  Unicode 10.0.

* bpo-30604: Move co_extra_freefuncs from per-thread to per-
  interpreter to avoid crashes.

* bpo-30597: "print" now shows expected input in custom error message
  when used as a Python 2 statement. Patch by Sanyam Khurana.

* bpo-30682: Removed a too-strict assertion that failed for certain
  f-strings, such as eval(“f’\n’”) and eval(“f’\r’”).

* bpo-30501: The compiler now produces more optimal code for complex
  condition expressions in the “if”, “while” and “assert” statement,
  the “if” expression, and generator expressions and comprehensions.

* bpo-28180: Implement **PEP 538** (legacy C locale coercion). This
  means that when a suitable coercion target locale is available, both
  the core interpreter and locale-aware C extensions will assume the
  use of UTF-8 as the default text encoding, rather than ASCII.

* bpo-30486: Allows setting cell values for __closure__. Patch by Lisa
  Roach.

* bpo-30537: itertools.islice now accepts integer-like objects (having
  an __index__ method) as start, stop, and slice arguments

* bpo-25324: Tokens needed for parsing in Python moved to C.
  "COMMENT", "NL" and "ENCODING". This way the tokens and tok_names in
  the token module don’t get changed when you import the tokenize
  module.

* bpo-29104: Fixed parsing backslashes in f-strings.

* bpo-27945: Fixed various segfaults with dict when input collections
  are mutated during searching, inserting or comparing.  Based on
  patches by Duane Griffin and Tim Mitchell.

* bpo-25794: Fixed type.__setattr__() and type.__delattr__() for non-
  interned attribute names.  Based on patch by Eryk Sun.

* bpo-30039: If a KeyboardInterrupt happens when the interpreter is in
  the middle of resuming a chain of nested ‘yield from’ or ‘await’
  calls, it’s now correctly delivered to the innermost frame.

* bpo-28974: "object.__format__(x, '')" is now equivalent to "str(x)"
  rather than "format(str(self), '')".

* bpo-30024: Circular imports involving absolute imports with binding
  a submodule to a name are now supported.

* bpo-12414: sys.getsizeof() on a code object now returns the sizes
  which includes the code struct and sizes of objects which it
  references. Patch by Dong-hee Na.

* bpo-29839: len() now raises ValueError rather than OverflowError if
  __len__() returned a large negative integer.

* bpo-11913: README.rst is now included in the list of distutils
  standard READMEs and therefore included in source distributions.

* bpo-29914: Fixed default implementations of __reduce__ and
  __reduce_ex__(). object.__reduce__() no longer takes arguments,
  object.__reduce_ex__() now requires one argument.

* bpo-29949: Fix memory usage regression of set and frozenset object.

* bpo-29935: Fixed error messages in the index() method of tuple, list
  and deque when pass indices of wrong type.

* bpo-29816: Shift operation now has less opportunity to raise
  OverflowError. ValueError always is raised rather than OverflowError
  for negative counts. Shifting zero with non-negative count always
  returns zero.

* bpo-24821: Fixed the slowing down to 25 times in the searching of
  some unlucky Unicode characters.

* bpo-29102: Add a unique ID to PyInterpreterState.  This makes it
  easier to identify each subinterpreter.

* bpo-29894: The deprecation warning is emitted if __complex__ returns
  an instance of a strict subclass of complex.  In a future versions
  of Python this can be an error.

* bpo-29859: Show correct error messages when any of the pthread_*
  calls in thread_pthread.h fails.

* bpo-29849: Fix a memory leak when an ImportError is raised during
  from import.

* bpo-28856: Fix an oversight that %b format for bytes should support
  objects follow the buffer protocol.

* bpo-29723: The "sys.path[0]" initialization change for bpo-29139
  caused a regression by revealing an inconsistency in how sys.path is
  initialized when executing "__main__" from a zipfile, directory, or
  other import location. The interpreter now consistently avoids ever
  adding the import location’s parent directory to "sys.path", and
  ensures no other "sys.path" entries are inadvertently modified when
  inserting the import location named on the command line.

* bpo-29568: Escaped percent “%%” in the format string for classic
  string formatting no longer allows any characters between two
  percents.

* bpo-29714: Fix a regression that bytes format may fail when
  containing zero bytes inside.

* bpo-29695: bool(), float(), list() and tuple() no longer take
  keyword arguments. The first argument of int() can now be passes
  only as positional argument.

* bpo-28893: Set correct __cause__ for errors about invalid awaitables
  returned from __aiter__ and __anext__.

* bpo-28876: "bool(range)" works even if "len(range)" raises
  "OverflowError".

* bpo-29683: Fixes to memory allocation in _PyCode_SetExtra.  Patch by
  Brian Coleman.

* bpo-29684: Fix minor regression of PyEval_CallObjectWithKeywords. It
  should raise TypeError when kwargs is not a dict.  But it might
  cause segv when args=NULL and kwargs is not a dict.

* bpo-28598: Support __rmod__ for subclasses of str being called
  before str.__mod__. Patch by Martijn Pieters.

* bpo-29607: Fix stack_effect computation for CALL_FUNCTION_EX. Patch
  by Matthieu Dartiailh.

* bpo-29602: Fix incorrect handling of signed zeros in complex
  constructor for complex subclasses and for inputs having a
  __complex__ method. Patch by Serhiy Storchaka.

* bpo-29347: Fixed possibly dereferencing undefined pointers when
  creating weakref objects.

* bpo-29463: Add "docstring" field to Module, ClassDef, FunctionDef,
  and AsyncFunctionDef ast nodes.  docstring is not first stmt in
  their body anymore.  It affects "co_firstlineno" and "co_lnotab" of
  code object for module and class. (Reverted in bpo-32911.)

* bpo-29438: Fixed use-after-free problem in key sharing dict.

* bpo-29546: Set the ‘path’ and ‘name’ attribute on ImportError for
  "from ... import ...".

* bpo-29546: Improve from-import error message with location

* bpo-29478: If max_line_length=None is specified while using the
  Compat32 policy, it is no longer ignored.  Patch by Mircea Cosbuc.

* bpo-29319: Prevent RunMainFromImporter overwriting sys.path[0].

* bpo-29337: Fixed possible BytesWarning when compare the code
  objects. Warnings could be emitted at compile time.

* bpo-29327: Fixed a crash when pass the iterable keyword argument to
  sorted().

* bpo-29034: Fix memory leak and use-after-free in os module
  (path_converter).

* bpo-29159: Fix regression in bytes(x) when x.__index__() raises
  Exception.

* bpo-29049: Call _PyObject_GC_TRACK() lazily when calling Python
  function. Calling function is up to 5% faster.

* bpo-28927: bytes.fromhex() and bytearray.fromhex() now ignore all
  ASCII whitespace, not only spaces.  Patch by Robert Xiao.

* bpo-28932: Do not include <sys/random.h> if it does not exist.

* bpo-25677: Correct the positioning of the syntax error caret for
  indented blocks. Based on patch by Michael Layzell.

* bpo-29000: Fixed bytes formatting of octals with zero padding in
  alternate form.

* bpo-18896: Python function can now have more than 255 parameters.
  collections.namedtuple() now supports tuples with more than 255
  elements.

* bpo-28596: The preferred encoding is UTF-8 on Android. Patch written
  by Chi Hsuan Yen.

* bpo-22257: Clean up interpreter startup (see **PEP 432**).

* bpo-26919: On Android, operating system data is now always
  encoded/decoded to/from UTF-8, instead of the locale encoding to
  avoid inconsistencies with os.fsencode() and os.fsdecode() which are
  already using UTF-8.

* bpo-28991: functools.lru_cache() was susceptible to an obscure
  reentrancy bug triggerable by a monkey-patched len() function.

* bpo-28147: Fix a memory leak in split-table dictionaries: setattr()
  must not convert combined table into split table. Patch written by
  INADA Naoki.

* bpo-28739: f-string expressions are no longer accepted as docstrings
  and by ast.literal_eval() even if they do not include expressions.

* bpo-28512: Fixed setting the offset attribute of SyntaxError by
  PyErr_SyntaxLocationEx() and PyErr_SyntaxLocationObject().

* bpo-28918: Fix the cross compilation of xxlimited when Python has
  been built with Py_DEBUG defined.

* bpo-23722: Rather than silently producing a class that doesn’t
  support zero-argument "super()" in methods, failing to pass the new
  "__classcell__" namespace entry up to "type.__new__" now results in
  a "DeprecationWarning" and a class that supports zero-argument
  "super()".

* bpo-28797: Modifying the class __dict__ inside the __set_name__
  method of a descriptor that is used inside that class no longer
  prevents calling the __set_name__ method of other descriptors.

* bpo-28799: Remove the "PyEval_GetCallStats()" function and deprecate
  the untested and undocumented "sys.callstats()" function. Remove the
  "CALL_PROFILE" special build: use the "sys.setprofile()" function,
  "cProfile" or "profile" to profile function calls.

* bpo-12844: More than 255 arguments can now be passed to a function.

* bpo-28782: Fix a bug in the implementation "yield from" when
  checking if the next instruction is YIELD_FROM. Regression
  introduced by WORDCODE (bpo-26647).

* bpo-28774: Fix error position of the unicode error in ASCII and
  Latin1 encoders when a string returned by the error handler contains
  multiple non-encodable characters (non-ASCII for the ASCII codec,
  characters out of the U+0000-U+00FF range for Latin1).

* bpo-28731: Optimize _PyDict_NewPresized() to create correct size
  dict. Improve speed of dict literal with constant keys up to 30%.

* bpo-28532: Show sys.version when -V option is supplied twice.

* bpo-27100: The with-statement now checks for __enter__ before it
  checks for __exit__. This gives less confusing error messages when
  both methods are missing. Patch by Jonathan Ellington.

* bpo-28746: Fix the set_inheritable() file descriptor method on
  platforms that do not have the ioctl FIOCLEX and FIONCLEX commands.

* bpo-26920: Fix not getting the locale’s charset upon initializing
  the interpreter, on platforms that do not have langinfo.

* bpo-28648: Fixed crash in Py_DecodeLocale() in debug build on Mac OS
  X when decode astral characters.  Patch by Xiang Zhang.

* bpo-28665: Improve speed of the STORE_DEREF opcode by 40%.

* bpo-19398: Extra slash no longer added to sys.path components in
  case of empty compile-time PYTHONPATH components.

* bpo-28621: Sped up converting int to float by reusing faster bits
  counting implementation.  Patch by Adrian Wielgosik.

* bpo-28580: Optimize iterating split table values. Patch by Xiang
  Zhang.

* bpo-28583: PyDict_SetDefault didn’t combine split table when needed.
  Patch by Xiang Zhang.

* bpo-28128: Deprecation warning for invalid str and byte escape
  sequences now prints better information about where the error
  occurs. Patch by Serhiy Storchaka and Eric Smith.

* bpo-28509: dict.update() no longer allocate unnecessary large
  memory.

* bpo-28426: Fixed potential crash in PyUnicode_AsDecodedObject() in
  debug build.

* bpo-28517: Fixed of-by-one error in the peephole optimizer that
  caused keeping unreachable code.

* bpo-28214: Improved exception reporting for problematic __set_name__
  attributes.

* bpo-23782: Fixed possible memory leak in _PyTraceback_Add() and
  exception loss in PyTraceBack_Here().

* bpo-28183: Optimize and cleanup dict iteration.

* bpo-26081: Added C implementation of asyncio.Future. Original patch
  by Yury Selivanov.

* bpo-28379: Added sanity checks and tests for
  PyUnicode_CopyCharacters(). Patch by Xiang Zhang.

* bpo-28376: The type of long range iterator is now registered as
  Iterator. Patch by Oren Milman.

* bpo-28376: Creating instances of range_iterator by calling
  range_iterator type now is disallowed.  Calling iter() on range
  instance is the only way. Patch by Oren Milman.

* bpo-26906: Resolving special methods of uninitialized type now
  causes implicit initialization of the type instead of a fail.

* bpo-18287: PyType_Ready() now checks that tp_name is not NULL.
  Original patch by Niklas Koep.

* bpo-24098: Fixed possible crash when AST is changed in process of
  compiling it.

* bpo-28201: Dict reduces possibility of 2nd conflict in hash table
  when hashes have same lower bits.

* bpo-28350: String constants with null character no longer interned.

* bpo-26617: Fix crash when GC runs during weakref callbacks.

* bpo-27942: String constants now interned recursively in tuples and
  frozensets.

* bpo-28289: ImportError.__init__ now resets not specified attributes.

* bpo-21578: Fixed misleading error message when ImportError called
  with invalid keyword args.

* bpo-28203: Fix incorrect type in complex(1.0, {2:3}) error message.
  Patch by Soumya Sharma.

* bpo-28086: Single var-positional argument of tuple subtype was
  passed unscathed to the C-defined function.  Now it is converted to
  exact tuple.

* bpo-28214: Now __set_name__ is looked up on the class instead of the
  instance.

* bpo-27955: Fallback on reading /dev/urandom device when the
  getrandom() syscall fails with EPERM, for example when blocked by
  SECCOMP.

* bpo-28192: Don’t import readline in isolated mode.

* bpo-27441: Remove some redundant assignments to ob_size in
  longobject.c. Thanks Oren Milman.

* bpo-27222: Clean up redundant code in long_rshift function. Thanks
  Oren Milman.

* Upgrade internal unicode databases to Unicode version 9.0.0.

* bpo-28131: Fix a regression in zipimport’s compile_source().
  zipimport should use the same optimization level as the interpreter.

* bpo-28126: Replace Py_MEMCPY with memcpy(). Visual Studio can
  properly optimize memcpy().

* bpo-28120: Fix dict.pop() for splitted dictionary when trying to
  remove a “pending key” (Not yet inserted in split-table). Patch by
  Xiang Zhang.

* bpo-26182: Raise DeprecationWarning when async and await keywords
  are used as variable/attribute/class/function name.

* bpo-26182: Fix a refleak in code that raises DeprecationWarning.

* bpo-28721: Fix asynchronous generators aclose() and athrow() to
  handle StopAsyncIteration propagation properly.

* bpo-26110: Speed-up method calls: add LOAD_METHOD and CALL_METHOD
  opcodes.


Library
-------

* bpo-31499: xml.etree: Fix a crash when a parser is part of a
  reference cycle.

* bpo-31482: "random.seed()" now works with bytes in version=1

* bpo-28556: typing.get_type_hints now finds the right globalns for
  classes and modules by default (when no "globalns" was specified by
  the caller).

* bpo-28556: Speed improvements to the "typing" module.  Original PRs
  by Ivan Levkivskyi and Mitar.

* bpo-31544: The C accelerator module of ElementTree ignored
  exceptions raised when looking up TreeBuilder target methods in
  XMLParser().

* bpo-31234: socket.create_connection() now fixes manually a reference
  cycle: clear the variable storing the last exception on success.

* bpo-31457: LoggerAdapter objects can now be nested.

* bpo-31431: SSLContext.check_hostname now automatically sets
  SSLContext.verify_mode to ssl.CERT_REQUIRED instead of failing with
  a ValueError.

* bpo-31233: socketserver.ThreadingMixIn now keeps a list of non-
  daemonic threads to wait until all these threads complete in
  server_close().

* bpo-28638: Changed the implementation strategy for
  collections.namedtuple() to substantially reduce the use of exec()
  in favor of precomputed methods. As a result, the *verbose*
  parameter and *_source* attribute are no longer supported.  The
  benefits include 1) having a smaller memory footprint for
  applications using multiple named tuples, 2) faster creation of the
  named tuple class (approx 4x to 6x depending on how it is measured),
  and 3) minor speed-ups for instance creation using __new__, _make,
  and _replace.  (The primary patch contributor is Jelle Zijlstra with
  further improvements by INADA Naoki, Serhiy Storchaka, and Raymond
  Hettinger.)

* bpo-31400: Improves SSL error handling to avoid losing error
  numbers.

* bpo-27629: Make return types of SSLContext.wrap_bio() and
  SSLContext.wrap_socket() customizable.

* bpo-28958: ssl.SSLContext() now uses OpenSSL error information when
  a context cannot be instantiated.

* bpo-28182: The SSL module now raises SSLCertVerificationError when
  OpenSSL fails to verify the peer’s certificate. The exception
  contains more information about the error.

* bpo-27340: SSLSocket.sendall() now uses memoryview to create slices
  of data. This fixes support for all bytes-like object. It is also
  more efficient and avoids costly copies.

* bpo-14191: A new function
  "argparse.ArgumentParser.parse_intermixed_args" provides the ability
  to parse command lines where there user intermixes options and
  positional arguments.

* bpo-31178: Fix string concatenation bug in rare error path in the
  subprocess module

* bpo-31350: Micro-optimize "asyncio._get_running_loop()" to become up
  to 10% faster.

* bpo-31170: expat: Update libexpat from 2.2.3 to 2.2.4. Fix copying
  of partial characters for UTF-8 input (libexpat bug 115):
  https://github.com/libexpat/libexpat/issues/115

* bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3.

* bpo-1198569: "string.Template" subclasses can optionally define
  "braceidpattern" if they want to specify different placeholder
  patterns inside and outside the braces.  If None (the default) it
  falls back to "idpattern".

* bpo-31326: concurrent.futures.ProcessPoolExecutor.shutdown() now
  explicitly closes the call queue. Moreover, shutdown(wait=True) now
  also join the call queue thread, to prevent leaking a dangling
  thread.

* bpo-27144: The "map()" and "as_completed()" iterators in
  "concurrent.futures" now avoid keeping a reference to yielded
  objects.

* bpo-31281: Fix "fileinput.FileInput(files, inplace=True)" when
  "files" contain "pathlib.Path" objects.

* bpo-10746: Fix ctypes producing wrong **PEP 3118** type codes for
  integer types.

* bpo-27584: "AF_VSOCK" has been added to the socket interface which
  allows communication between virtual machines and their host.

* bpo-22536: The subprocess module now sets the filename when
  FileNotFoundError is raised on POSIX systems due to the executable
  or cwd not being found.

* bpo-29741: Update some methods in the _pyio module to also accept
  integer types. Patch by Oren Milman.

* bpo-31249: concurrent.futures: WorkItem.run() used by
  ThreadPoolExecutor now breaks a reference cycle between an exception
  object and the WorkItem object.

* bpo-31247: xmlrpc.server now explicitly breaks reference cycles when
  using sys.exc_info() in code handling exceptions.

* bpo-23835: configparser: reading defaults in the "ConfigParser()"
  constructor is now using "read_dict()", making its behavior
  consistent with the rest of the parser.  Non-string keys and values
  in the defaults dictionary are now being implicitly converted to
  strings.  Patch by James Tocknell.

* bpo-31238: pydoc: the stop() method of the private ServerThread
  class now waits until DocServer.serve_until_quit() completes and
  then explicitly sets its docserver attribute to None to break a
  reference cycle.

* bpo-5001: Many asserts in "multiprocessing" are now more
  informative, and some error types have been changed to more specific
  ones.

* bpo-31109: Convert zipimport to use Argument Clinic.

* bpo-30102: The ssl and hashlib modules now call
  OPENSSL_add_all_algorithms_noconf() on OpenSSL < 1.1.0. The function
  detects CPU features and enables optimizations on some CPU
  architectures such as POWER8. Patch is based on research from
  Gustavo Serra Scalet.

* bpo-18966: Non-daemonic threads created by a multiprocessing.Process
  are now joined on child exit.

* bpo-31183: "dis" now works with asynchronous generator and coroutine
  objects. Patch by George Collins based on diagnosis by Luciano
  Ramalho.

* bpo-5001: There are a number of uninformative asserts in the
  "multiprocessing" module, as noted in issue 5001. This change fixes
  two of the most potentially problematic ones, since they are in
  error-reporting code, in the
  "multiprocessing.managers.convert_to_error" function. (It also makes
  more informative a ValueError message.) The only potentially
  problematic change is that the AssertionError is now a TypeError;
  however, this should also help distinguish it from an AssertionError
  being *reported* by the function/its caller (such as in issue
  31169). - Patch by Allen W. Smith (drallensmith on github).

* bpo-31185: Fixed miscellaneous errors in asyncio speedup module.

* bpo-31151: socketserver.ForkingMixIn.server_close() now waits until
  all child processes completed to prevent leaking zombie processes.

* bpo-31072: Add an "include_file" parameter to
  "zipapp.create_archive()"

* bpo-24700: Optimize array.array comparison. It is now from 10x up to
  70x faster when comparing arrays holding values of the same integer
  type.

* bpo-31135: ttk: fix the destroy() method of LabeledScale and
  OptionMenu classes. Call the parent destroy() method even if the
  used attribute doesn’t exist. The LabeledScale.destroy() method now
  also explicitly clears label and scale attributes to help the
  garbage collector to destroy all widgets.

* bpo-31107: Fix "copyreg._slotnames()" mangled attribute calculation
  for classes whose name begins with an underscore. Patch by Shane
  Harvey.

* bpo-31080: Allow "logging.config.fileConfig" to accept kwargs and/or
  args.

* bpo-30897: "pathlib.Path" objects now include an "is_mount()" method
  (only implemented on POSIX).  This is similar to
  "os.path.ismount(p)". Patch by Cooper Ry Lees.

* bpo-31061: Fixed a crash when using asyncio and threads.

* bpo-30987: Added support for CAN ISO-TP protocol in the socket
  module.

* bpo-30522: Added a "setStream" method to "logging.StreamHandler" to
  allow the stream to be set after creation.

* bpo-30502: Fix handling of long oids in ssl.  Based on patch by
  Christian Heimes.

* bpo-5288: Support tzinfo objects with sub-minute offsets.

* bpo-30919: Fix shared memory performance regression in
  multiprocessing in 3.x. Shared memory used anonymous memory mappings
  in 2.x, while 3.x mmaps actual files. Try to be careful to do as
  little disk I/O as possible.

* bpo-26732: Fix too many fds in processes started with the
  “forkserver” method. A child process would inherit as many fds as
  the number of still-running children.

* bpo-29403: Fix "unittest.mock"’s autospec to not fail on method-
  bound builtin functions.  Patch by Aaron Gallagher.

* bpo-30961: Fix decrementing a borrowed reference in tracemalloc.

* bpo-19896: Fix multiprocessing.sharedctypes to recognize typecodes
  "'q'" and "'Q'".

* bpo-30946: Remove obsolete code in readline module for platforms
  where GNU readline is older than 2.1 or where select() is not
  available.

* bpo-25684: Change "ttk.OptionMenu" radiobuttons to be unique across
  instances of "OptionMenu".

* bpo-30886: Fix multiprocessing.Queue.join_thread(): it now waits
  until the thread completes, even if the thread was started by the
  same process which created the queue.

* bpo-29854: Fix segfault in readline when using readline’s history-
  size option.  Patch by Nir Soffer.

* bpo-30794: Added multiprocessing.Process.kill method to terminate
  using the SIGKILL signal on Unix.

* bpo-30319: socket.close() now ignores ECONNRESET error.

* bpo-30828: Fix out of bounds write in
  "asyncio.CFuture.remove_done_callback()".

* bpo-30302: Use keywords in the "repr" of "datetime.timedelta".

* bpo-30807: signal.setitimer() may disable the timer when passed a
  tiny value. Tiny values (such as 1e-6) are valid non-zero values for
  setitimer(), which is specified as taking microsecond-resolution
  intervals. However, on some platform, our conversion routine could
  convert 1e-6 into a zero interval, therefore disabling the timer
  instead of (re-)scheduling it.

* bpo-30441: Fix bug when modifying os.environ while iterating over it

* bpo-29585: Avoid importing "sysconfig" from "site" to improve
  startup speed. Python startup is about 5% faster on Linux and 30%
  faster on macOS.

* bpo-29293: Add missing parameter “n” on
  multiprocessing.Condition.notify(). The doc claims
  multiprocessing.Condition behaves like threading.Condition, but its
  notify() method lacked the optional “n” argument (to specify the
  number of sleepers to wake up) that threading.Condition.notify()
  accepts.

* bpo-30532: Fix email header value parser dropping folding white
  space in certain cases.

* bpo-30596: Add a "close()" method to "multiprocessing.Process".

* bpo-9146: Fix a segmentation fault in _hashopenssl when standard
  hash functions such as md5 are not available in the linked OpenSSL
  library.  As in some special FIPS-140 build environments.

* bpo-29169: Update zlib to 1.2.11.

* bpo-30119: ftplib.FTP.putline() now throws ValueError on commands
  that contains CR or LF. Patch by Dong-hee Na.

* bpo-30879: os.listdir() and os.scandir() now emit bytes names when
  called with bytes-like argument.

* bpo-30746: Prohibited the ‘=’ character in environment variable
  names in "os.putenv()" and "os.spawn*()".

* bpo-30664: The description of a unittest subtest now preserves the
  order of keyword arguments of TestCase.subTest().

* bpo-21071: struct.Struct.format type is now "str" instead of
  "bytes".

* bpo-29212: Fix concurrent.futures.thread.ThreadPoolExecutor threads
  to have a non repr() based thread name by default when no
  thread_name_prefix is supplied. They will now identify themselves as
  “ThreadPoolExecutor-y_n”.

* bpo-29755: Fixed the lgettext() family of functions in the gettext
  module. They now always return bytes.

* bpo-30616: Functional API of enum allows to create empty enums.
  Patched by Dong-hee Na

* bpo-30038: Fix race condition between signal delivery and wakeup
  file descriptor. Patch by Nathaniel Smith.

* bpo-23894: lib2to3 now recognizes "rb'...'" and "f'...'" strings.

* bpo-24744: pkgutil.walk_packages function now raises ValueError if
  *path* is a string. Patch by Sanyam Khurana.

* bpo-24484: Avoid race condition in multiprocessing cleanup.

* bpo-30589: Fix multiprocessing.Process.exitcode to return the
  opposite of the signal number when the process is killed by a signal
  (instead of 255) when using the “forkserver” method.

* bpo-28994: The traceback no longer displayed for SystemExit raised
  in a callback registered by atexit.

* bpo-30508: Don’t log exceptions if Task/Future “cancel()” method was
  called.

* bpo-30645: Fix path calculation in "imp.load_package()", fixing it
  for cases when a package is only shipped with bytecodes. Patch by
  Alexandru Ardelean.

* bpo-11822: The dis.dis() function now is able to disassemble nested
  code objects.

* bpo-30624: selectors does not take KeyboardInterrupt and SystemExit
  into account, leaving a fd in a bad state in case of error. Patch by
  Giampaolo Rodola’.

* bpo-30595: multiprocessing.Queue.get() with a timeout now polls its
  reader in non-blocking mode if it succeeded to acquire the lock but
  the acquire took longer than the timeout.

* bpo-28556: Updates to typing module: Add generic
  AsyncContextManager, add support for ContextManager on all versions.
  Original PRs by Jelle Zijlstra and Ivan Levkivskyi

* bpo-30605: re.compile() no longer raises a BytesWarning when
  compiling a bytes instance with misplaced inline modifier.  Patch by
  Roy Williams.

* bpo-29870: Fix ssl sockets leaks when connection is aborted in
  asyncio/ssl implementation. Patch by Michaël Sghaïer.

* bpo-29743: Closing transport during handshake process leaks open
  socket. Patch by Nikolay Kim

* bpo-27585: Fix waiter cancellation in asyncio.Lock. Patch by Mathieu
  Sornay.

* bpo-30014: modify() method of poll(), epoll() and devpoll() based
  classes of selectors module is around 10% faster.  Patch by
  Giampaolo Rodola’.

* bpo-30418: On Windows, subprocess.Popen.communicate() now also
  ignore EINVAL on stdin.write() if the child process is still running
  but closed the pipe.

* bpo-30463: Addded empty __slots__ to abc.ABC.  This allows
  subclassers to deny __dict__ and __weakref__ creation.  Patch by
  Aaron Hall.

* bpo-30520: Loggers are now pickleable.

* bpo-30557: faulthandler now correctly filters and displays exception
  codes on Windows

* bpo-30526: Add TextIOWrapper.reconfigure() and a
  TextIOWrapper.write_through attribute.

* bpo-30245: Fix possible overflow when organize struct.pack_into
  error message.  Patch by Yuan Liu.

* bpo-30378: Fix the problem that logging.handlers.SysLogHandler
  cannot handle IPv6 addresses.

* bpo-16500: Allow registering at-fork handlers.

* bpo-30470: Deprecate invalid ctypes call protection on Windows.
  Patch by Mariatta Wijaya.

* bpo-30414: multiprocessing.Queue._feed background running thread do
  not break from main loop on exception.

* bpo-30003: Fix handling escape characters in HZ codec.  Based on
  patch by Ma Lin.

* bpo-30149: inspect.signature() now supports callables with variable-
  argument parameters wrapped with partialmethod. Patch by Dong-hee
  Na.

* bpo-30436: importlib.find_spec() raises ModuleNotFoundError instead
  of AttributeError if the specified parent module is not a package
  (i.e. lacks a __path__ attribute).

* bpo-30301: Fix AttributeError when using SimpleQueue.empty() under
  *spawn* and *forkserver* start methods.

* bpo-30375: Warnings emitted when compile a regular expression now
  always point to the line in the user code.  Previously they could
  point into inners of the re module if emitted from inside of groups
  or conditionals.

* bpo-30329: imaplib and poplib now catch the Windows socket WSAEINVAL
  error (code 10022) on shutdown(SHUT_RDWR): An invalid operation was
  attempted. This error occurs sometimes on SSL connections.

* bpo-29196: Removed previously deprecated in Python 2.4 classes
  Plist, Dict and _InternalDict in the plistlib module.  Dict values
  in the result of functions readPlist() and readPlistFromBytes() are
  now normal dicts.  You no longer can use attribute access to access
  items of these dictionaries.

* bpo-9850: The "macpath" is now deprecated and will be removed in
  Python 3.8.

* bpo-30299: Compiling regular expression in debug mode on CPython now
  displays the compiled bytecode in human readable form.

* bpo-30048: Fixed "Task.cancel()" can be ignored when the task is
  running coroutine and the coroutine returned without any more
  "await".

* bpo-30266: contextlib.AbstractContextManager now supports anti-
  registration by setting __enter__ = None or __exit__ = None,
  following the pattern introduced in bpo-25958. Patch by Jelle
  Zijlstra.

* bpo-30340: Enhanced regular expressions optimization. This increased
  the performance of matching some patterns up to 25 times.

* bpo-30298: Weaken the condition of deprecation warnings for inline
  modifiers. Now allowed several subsequential inline modifiers at the
  start of the pattern (e.g. "'(?i)(?s)...'").  In verbose mode
  whitespaces and comments now are allowed before and between inline
  modifiers (e.g. "'(?x) (?i) (?s)...'").

* bpo-30285: Optimized case-insensitive matching and searching of
  regular expressions.

* bpo-29990: Fix range checking in GB18030 decoder.  Original patch by
  Ma Lin.

* bpo-29979: rewrite cgi.parse_multipart, reusing the FieldStorage
  class and making its results consistent with those of FieldStorage
  for multipart/form-data requests. Patch by Pierre Quentel.

* bpo-30243: Removed the __init__ methods of _json’s scanner and
  encoder. Misusing them could cause memory leaks or crashes.  Now
  scanner and encoder objects are completely initialized in the
  __new__ methods.

* bpo-30215: Compiled regular expression objects with the re.LOCALE
  flag no longer depend on the locale at compile time.  Only the
  locale at matching time affects the result of matching.

* bpo-30185: Avoid KeyboardInterrupt tracebacks in forkserver helper
  process when Ctrl-C is received.

* bpo-30103: binascii.b2a_uu() and uu.encode() now support using "'`'"
  as zero instead of space.

* bpo-28556: Various updates to typing module: add typing.NoReturn
  type, use WrapperDescriptorType, minor bug-fixes.  Original PRs by
  Jim Fasarakis-Hilliard and Ivan Levkivskyi.

* bpo-30205: Fix getsockname() for unbound AF_UNIX sockets on Linux.

* bpo-30228: The seek() and tell() methods of io.FileIO now set the
  internal seekable attribute to avoid one syscall on open() (in
  buffered or text mode).

* bpo-30190: unittest’s assertAlmostEqual and assertNotAlmostEqual
  provide a better message in case of failure which includes the
  difference between left and right arguments.  (patch by Giampaolo
  Rodola’)

* bpo-30101: Add support for curses.A_ITALIC.

* bpo-29822: inspect.isabstract() now works during __init_subclass__.
  Patch by Nate Soares.

* bpo-29960: Preserve generator state when _random.Random.setstate()
  raises an exception. Patch by Bryan Olson.

* bpo-30070: Fixed leaks and crashes in errors handling in the parser
  module.

* bpo-22352: Column widths in the output of dis.dis() are now adjusted
  for large line numbers and instruction offsets.

* bpo-30061: Fixed crashes in IOBase methods __next__() and
  readlines() when readline() or __next__() respectively return non-
  sizeable object. Fixed possible other errors caused by not checking
  results of PyObject_Size(), PySequence_Size(), or PyMapping_Size().

* bpo-30218: Fix PathLike support for shutil.unpack_archive. Patch by
  Jelle Zijlstra.

* bpo-10076: Compiled regular expression and match objects in the re
  module now support copy.copy() and copy.deepcopy() (they are
  considered atomic).

* bpo-30068: _io._IOBase.readlines will check if it’s closed first
  when hint is present.

* bpo-29694: Fixed race condition in pathlib mkdir with flags
  parents=True. Patch by Armin Rigo.

* bpo-29692: Fixed arbitrary unchaining of RuntimeError exceptions in
  contextlib.contextmanager.  Patch by Siddharth Velankar.

* bpo-26187: Test that sqlite3 trace callback is not called multiple
  times when schema is changing.  Indirectly fixed by switching to use
  sqlite3_prepare_v2() in bpo-9303.  Patch by Aviv Palivoda.

* bpo-30017: Allowed calling the close() method of the zip entry
  writer object multiple times.  Writing to a closed writer now always
  produces a ValueError.

* bpo-29998: Pickling and copying ImportError now preserves name and
  path attributes.

* bpo-29995: re.escape() now escapes only regex special characters.

* bpo-29962: Add math.remainder operation, implementing remainder as
  specified in IEEE 754.

* bpo-29649: Improve struct.pack_into() exception messages for
  problems with the buffer size and offset.  Patch by Andrew Nester.

* bpo-29654: Support If-Modified-Since HTTP header (browser cache).
  Patch by Pierre Quentel.

* bpo-29931: Fixed comparison check for ipaddress.ip_interface
  objects. Patch by Sanjay Sundaresan.

* bpo-29953: Fixed memory leaks in the replace() method of datetime
  and time objects when pass out of bound fold argument.

* bpo-29942: Fix a crash in itertools.chain.from_iterable when
  encountering long runs of empty iterables.

* bpo-10030: Sped up reading encrypted ZIP files by 2 times.

* bpo-29204: Element.getiterator() and the html parameter of
  XMLParser() were deprecated only in the documentation (since Python
  3.2 and 3.4 correspondingly). Now using them emits a deprecation
  warning.

* bpo-27863: Fixed multiple crashes in ElementTree caused by race
  conditions and wrong types.

* bpo-25996: Added support of file descriptors in os.scandir() on
  Unix. os.fwalk() is sped up by 2 times by using os.scandir().

* bpo-28699: Fixed a bug in pools in multiprocessing.pool that raising
  an exception at the very first of an iterable may swallow the
  exception or make the program hang. Patch by Davin Potts and Xiang
  Zhang.

* bpo-23890: unittest.TestCase.assertRaises() now manually breaks a
  reference cycle to not keep objects alive longer than expected.

* bpo-29901: The zipapp module now supports general path-like objects,
  not just pathlib.Path.

* bpo-25803: Avoid incorrect errors raised by
  Path.mkdir(exist_ok=True) when the OS gives priority to errors such
  as EACCES over EEXIST.

* bpo-29861: Release references to tasks, their arguments and their
  results as soon as they are finished in multiprocessing.Pool.

* bpo-19930: The mode argument of os.makedirs() no longer affects the
  file permission bits of newly created intermediate-level
  directories.

* bpo-29884: faulthandler: Restore the old sigaltstack during
  teardown. Patch by Christophe Zeitouny.

* bpo-25455: Fixed crashes in repr of recursive buffered file-like
  objects.

* bpo-29800: Fix crashes in partial.__repr__ if the keys of
  partial.keywords are not strings.  Patch by Michael Seifert.

* bpo-8256: Fixed possible failing or crashing input() if attributes
  “encoding” or “errors” of sys.stdin or sys.stdout are not set or are
  not strings.

* bpo-28692: Using non-integer value for selecting a plural form in
  gettext is now deprecated.

* bpo-26121: Use C library implementation for math functions erf() and
  erfc().

* bpo-29619: os.stat() and os.DirEntry.inode() now convert inode
  (st_ino) using unsigned integers.

* bpo-28298: Fix a bug that prevented array ‘Q’, ‘L’ and ‘I’ from
  accepting big intables (objects that have __int__) as elements.

* bpo-29645: Speed up importing the webbrowser module.
  webbrowser.register() is now thread-safe.

* bpo-28231: The zipfile module now accepts path-like objects for
  external paths.

* bpo-26915: index() and count() methods of collections.abc.Sequence
  now check identity before checking equality when do comparisons.

* bpo-28682: Added support for bytes paths in os.fwalk().

* bpo-29728: Add new "socket.TCP_NOTSENT_LOWAT" (Linux 3.12) constant.
  Patch by Nathaniel J. Smith.

* bpo-29623: Allow use of path-like object as a single argument in
  ConfigParser.read(). Patch by David Ellis.

* bpo-9303: Migrate sqlite3 module to _v2 API.  Patch by Aviv
  Palivoda.

* bpo-28963: Fix out of bound iteration in
  asyncio.Future.remove_done_callback implemented in C.

* bpo-29704: asyncio.subprocess.SubprocessStreamProtocol no longer
  closes before all pipes are closed.

* bpo-29271: Fix Task.current_task and Task.all_tasks implemented in C
  to accept None argument as their pure Python implementation.

* bpo-29703: Fix asyncio to support instantiation of new event loops
  in child processes.

* bpo-29615: SimpleXMLRPCDispatcher no longer chains KeyError (or any
  other exception) to exception(s) raised in the dispatched methods.
  Patch by Petr Motejlek.

* bpo-7769: Method register_function() of
  xmlrpc.server.SimpleXMLRPCDispatcher and its subclasses can now be
  used as a decorator.

* bpo-29376: Fix assertion error in threading._DummyThread.is_alive().

* bpo-28624: Add a test that checks that cwd parameter of Popen()
  accepts PathLike objects.  Patch by Sayan Chowdhury.

* bpo-28518: Start a transaction implicitly before a DML statement.
  Patch by Aviv Palivoda.

* bpo-29742: get_extra_info() raises exception if get called on closed
  ssl transport. Patch by Nikolay Kim.

* bpo-16285: urllib.parse.quote is now based on RFC 3986 and hence
  includes ‘~’ in the set of characters that is not quoted by default.
  Patch by Christian Theune and Ratnadeep Debnath.

* bpo-29532: Altering a kwarg dictionary passed to functools.partial()
  no longer affects a partial object after creation.

* bpo-29110: Fix file object leak in aifc.open() when file is given as
  a filesystem path and is not in valid AIFF format. Patch by Anthony
  Zhang.

* bpo-22807: Add uuid.SafeUUID and uuid.UUID.is_safe to relay
  information from the platform about whether generated UUIDs are
  generated with a multiprocessing safe method.

* bpo-29576: Improve some deprecations in importlib. Some deprecated
  methods now emit DeprecationWarnings and have better descriptive
  messages.

* bpo-29534: Fixed different behaviour of Decimal.from_float() for
  _decimal and _pydecimal. Thanks Andrew Nester.

* bpo-10379: locale.format_string now supports the ‘monetary’ keyword
  argument, and locale.format is deprecated.

* bpo-29851: importlib.reload() now raises ModuleNotFoundError if the
  module lacks a spec.

* bpo-28556: Various updates to typing module: typing.Counter,
  typing.ChainMap, improved ABC caching, etc. Original PRs by Jelle
  Zijlstra, Ivan Levkivskyi, Manuel Krebber, and Łukasz Langa.

* bpo-29100: Fix datetime.fromtimestamp() regression introduced in
  Python 3.6.0: check minimum and maximum years.

* bpo-29416: Prevent infinite loop in pathlib.Path.mkdir

* bpo-29444: Fixed out-of-bounds buffer access in the group() method
  of the match object. Based on patch by WGH.

* bpo-29377: Add WrapperDescriptorType, MethodWrapperType, and
  MethodDescriptorType built-in types to types module. Original patch
  by Manuel Krebber.

* bpo-29218: Unused install_misc command is now removed.  It has been
  documented as unused since 2000.  Patch by Eric N. Vander Weele.

* bpo-29368: The extend() method is now called instead of the append()
  method when unpickle collections.deque and other list-like objects.
  This can speed up unpickling to 2 times.

* bpo-29338: The help of a builtin or extension class now includes the
  constructor signature if __text_signature__ is provided for the
  class.

* bpo-29335: Fix subprocess.Popen.wait() when the child process has
  exited to a stopped instead of terminated state (ex: when under
  ptrace).

* bpo-29290: Fix a regression in argparse that help messages would
  wrap at non-breaking spaces.

* bpo-28735: Fixed the comparison of mock.MagickMock with mock.ANY.

* bpo-29197: Removed deprecated function ntpath.splitunc().

* bpo-29210: Removed support of deprecated argument “exclude” in
  tarfile.TarFile.add().

* bpo-29219: Fixed infinite recursion in the repr of uninitialized
  ctypes.CDLL instances.

* bpo-29192: Removed deprecated features in the http.cookies module.

* bpo-29193: A format string argument for string.Formatter.format() is
  now positional-only.

* bpo-29195: Removed support of deprecated undocumented keyword
  arguments in methods of regular expression objects.

* bpo-28969: Fixed race condition in C implementation of
  functools.lru_cache. KeyError could be raised when cached function
  with full cache was simultaneously called from different threads
  with the same uncached arguments.

* bpo-20804: The unittest.mock.sentinel attributes now preserve their
  identity when they are copied or pickled.

* bpo-29142: In urllib.request, suffixes in no_proxy environment
  variable with leading dots could match related hostnames again (e.g.
  .b.c matches a.b.c). Patch by Milan Oberkirch.

* bpo-28961: Fix unittest.mock._Call helper: don’t ignore the name
  parameter anymore. Patch written by Jiajun Huang.

* bpo-15812: inspect.getframeinfo() now correctly shows the first line
  of a context. Patch by Sam Breese.

* bpo-28985: Update authorizer constants in sqlite3 module. Patch by
  Dingyuan Wang.

* bpo-29079: Prevent infinite loop in pathlib.resolve() on Windows

* bpo-13051: Fixed recursion errors in large or resized
  curses.textpad.Textbox.  Based on patch by Tycho Andersen.

* bpo-9770: curses.ascii predicates now work correctly with negative
  integers.

* bpo-28427: old keys should not remove new values from
  WeakValueDictionary when collecting from another thread.

* bpo-28923: Remove editor artifacts from Tix.py.

* bpo-28871: Fixed a crash when deallocate deep ElementTree.

* bpo-19542: Fix bugs in WeakValueDictionary.setdefault() and
  WeakValueDictionary.pop() when a GC collection happens in another
  thread.

* bpo-20191: Fixed a crash in resource.prlimit() when passing a
  sequence that doesn’t own its elements as limits.

* bpo-16255: subprocess.Popen uses /system/bin/sh on Android as the
  shell, instead of /bin/sh.

* bpo-28779: multiprocessing.set_forkserver_preload() would crash the
  forkserver process if a preloaded module instantiated some
  multiprocessing objects such as locks.

* bpo-26937: The chown() method of the tarfile.TarFile class does not
  fail now when the grp module cannot be imported, as for example on
  Android platforms.

* bpo-28847: dbm.dumb now supports reading read-only files and no
  longer writes the index file when it is not changed.  A deprecation
  warning is now emitted if the index file is missed and recreated in
  the ‘r’ and ‘w’ modes (will be an error in future Python releases).

* bpo-27030: Unknown escapes consisting of "'\'" and an ASCII letter
  in re.sub() replacement templates regular expressions now are
  errors.

* bpo-28835: Fix a regression introduced in warnings.catch_warnings():
  call warnings.showwarning() if it was overridden inside the context
  manager.

* bpo-27172: To assist with upgrades from 2.7, the previously
  documented deprecation of "inspect.getfullargspec()" has been
  reversed. This decision may be revisited again after the Python 2.7
  branch is no longer officially supported.

* bpo-28740: Add sys.getandroidapilevel(): return the build time API
  version of Android as an integer. Function only available on
  Android.

* bpo-26273: Add new "socket.TCP_CONGESTION" (Linux 2.6.13) and
  "socket.TCP_USER_TIMEOUT" (Linux 2.6.37) constants. Patch written by
  Omar Sandoval.

* bpo-28752: Restored the __reduce__() methods of datetime objects.

* bpo-28727: Regular expression patterns, _sre.SRE_Pattern objects
  created by re.compile(), become comparable (only x==y and x!=y
  operators). This change should fix the bpo-18383: don’t duplicate
  warning filters when the warnings module is reloaded (thing usually
  only done in unit tests).

* bpo-20572: Remove the subprocess.Popen.wait endtime parameter.  It
  was deprecated in 3.4 and undocumented prior to that.

* bpo-25659: In ctypes, prevent a crash calling the from_buffer() and
  from_buffer_copy() methods on abstract classes like Array.

* bpo-28548: In the “http.server” module, parse the protocol version
  if possible, to avoid using HTTP 0.9 in some error responses.

* bpo-19717: Makes Path.resolve() succeed on paths that do not exist.
  Patch by Vajrasky Kok

* bpo-28563: Fixed possible DoS and arbitrary code execution when
  handle plural form selections in the gettext module.  The expression
  parser now supports exact syntax supported by GNU gettext.

* bpo-28387: Fixed possible crash in _io.TextIOWrapper deallocator
  when the garbage collector is invoked in other thread.  Based on
  patch by Sebastian Cufre.

* bpo-27517: LZMA compressor and decompressor no longer raise
  exceptions if given empty data twice.  Patch by Benjamin Fogle.

* bpo-28549: Fixed segfault in curses’s addch() with ncurses6.

* bpo-28449: tarfile.open() with mode “r” or “r:” now tries to open a
  tar file with compression before trying to open it without
  compression. Otherwise it had 50% chance failed with
  ignore_zeros=True.

* bpo-23262: The webbrowser module now supports Firefox 36+ and
  derived browsers.  Based on patch by Oleg Broytman.

* bpo-24241: The webbrowser in an X environment now prefers using the
  default browser directly. Also, the webbrowser register() function
  now has a documented ‘preferred’ argument, to specify browsers to be
  returned by get() with no arguments. Patch by David Steele

* bpo-27939: Fixed bugs in tkinter.ttk.LabeledScale and tkinter.Scale
  caused by representing the scale as float value internally in Tk.
  tkinter.IntVar now works if float value is set to underlying Tk
  variable.

* bpo-28255: calendar.TextCalendar.prweek() no longer prints a space
  after a weeks’s calendar.  calendar.TextCalendar.pryear() no longer
  prints redundant newline after a year’s calendar.  Based on patch by
  Xiang Zhang.

* bpo-28255: calendar.TextCalendar.prmonth() no longer prints a space
  at the start of new line after printing a month’s calendar.  Patch
  by Xiang Zhang.

* bpo-20491: The textwrap.TextWrapper class now honors non-breaking
  spaces. Based on patch by Kaarle Ritvanen.

* bpo-28353: os.fwalk() no longer fails on broken links.

* bpo-28430: Fix iterator of C implemented asyncio.Future doesn’t
  accept non-None value is passed to it.send(val).

* bpo-27025: Generated names for Tkinter widgets now start by the “!”
  prefix for readability.

* bpo-25464: Fixed HList.header_exists() in tkinter.tix module by
  addin a workaround to Tix library bug.

* bpo-28488: shutil.make_archive() no longer adds entry “./” to ZIP
  archive.

* bpo-25953: re.sub() now raises an error for invalid numerical group
  reference in replacement template even if the pattern is not found
  in the string.  Error message for invalid group reference now
  includes the group index and the position of the reference. Based on
  patch by SilentGhost.

* bpo-28469: timeit now uses the sequence 1, 2, 5, 10, 20, 50,…
  instead of 1, 10, 100,… for autoranging.

* bpo-28115: Command-line interface of the zipfile module now uses
  argparse. Added support of long options.

* bpo-18219: Optimize csv.DictWriter for large number of columns.
  Patch by Mariatta Wijaya.

* bpo-28448: Fix C implemented asyncio.Future didn’t work on Windows.

* bpo-23214: In the “io” module, the argument to BufferedReader and
  BytesIO’s read1() methods is now optional and can be -1, matching
  the BufferedIOBase specification.

* bpo-28480: Fix error building socket module when multithreading is
  disabled.

* bpo-28240: timeit: remove "-c/--clock" and "-t/--time" command line
  options which were deprecated since Python 3.3.

* bpo-28240: timeit now repeats the benchmarks 5 times instead of only
  3 to make benchmarks more reliable.

* bpo-28240: timeit autorange now uses a single loop iteration if the
  benchmark takes less than 10 seconds, instead of 10 iterations.
  “python3 -m timeit -s ‘import time’ ‘time.sleep(1)’” now takes 4
  seconds instead of 40 seconds.

* Distutils.sdist now looks for README and setup.py files with case
  sensitivity. This behavior matches that found in Setuptools 6.0 and
  later. See setuptools 100 for rationale.

* bpo-24452: Make webbrowser support Chrome on Mac OS X. Patch by Ned
  Batchelder.

* bpo-20766: Fix references leaked by pdb in the handling of SIGINT
  handlers.

* bpo-27998: Fixed bytes path support in os.scandir() on Windows.
  Patch by Eryk Sun.

* bpo-28317: The disassembler now decodes FORMAT_VALUE argument.

* bpo-28380: unittest.mock Mock autospec functions now properly
  support assert_called, assert_not_called, and assert_called_once.

* bpo-28229: lzma module now supports pathlib.

* bpo-28321: Fixed writing non-BMP characters with binary format in
  plistlib.

* bpo-28225: bz2 module now supports pathlib.  Initial patch by Ethan
  Furman.

* bpo-28227: gzip now supports pathlib.  Patch by Ethan Furman.

* bpo-28332: Deprecated silent truncations in socket.htons and
  socket.ntohs. Original patch by Oren Milman.

* bpo-27358: Optimized merging var-keyword arguments and improved
  error message when passing a non-mapping as a var-keyword argument.

* bpo-28257: Improved error message when passing a non-iterable as a
  var-positional argument.  Added opcode BUILD_TUPLE_UNPACK_WITH_CALL.

* bpo-28322: Fixed possible crashes when unpickle itertools objects
  from incorrect pickle data.  Based on patch by John Leitch.

* bpo-28228: imghdr now supports pathlib.

* bpo-28226: compileall now supports pathlib.

* bpo-28314: Fix function declaration (C flags) for the getiterator()
  method of xml.etree.ElementTree.Element.

* bpo-28148: Stop using localtime() and gmtime() in the time module.
  Introduced platform independent _PyTime_localtime API that is
  similar to POSIX localtime_r, but available on all platforms.  Patch
  by Ed Schouten.

* bpo-28253: Fixed calendar functions for extreme months: 0001-01 and
  9999-12. Methods itermonthdays() and itermonthdays2() are
  reimplemented so that they don’t call itermonthdates() which can
  cause datetime.date under/overflow.

* bpo-28275: Fixed possible use after free in the decompress() methods
  of the LZMADecompressor and BZ2Decompressor classes. Original patch
  by John Leitch.

* bpo-27897: Fixed possible crash in
  sqlite3.Connection.create_collation() if pass invalid string-like
  object as a name.  Patch by Xiang Zhang.

* bpo-18844: random.choices() now has k as a keyword-only argument to
  improve the readability of common cases and come into line with the
  signature used in other languages.

* bpo-18893: Fix invalid exception handling in
  Lib/ctypes/macholib/dyld.py. Patch by Madison May.

* bpo-27611: Fixed support of default root window in the tkinter.tix
  module. Added the master parameter in the DisplayStyle constructor.

* bpo-27348: In the traceback module, restore the formatting of
  exception messages like “Exception: None”.  This fixes a regression
  introduced in 3.5a2.

* bpo-25651: Allow falsy values to be used for msg parameter of
  subTest().

* bpo-27778: Fix a memory leak in os.getrandom() when the getrandom()
  is interrupted by a signal and a signal handler raises a Python
  exception.

* bpo-28200: Fix memory leak on Windows in the os module (fix
  path_converter() function).

* bpo-25400: RobotFileParser now correctly returns default values for
  crawl_delay and request_rate.  Initial patch by Peter Wirtz.

* bpo-27932: Prevent memory leak in win32_ver().

* Fix UnboundLocalError in socket._sendfile_use_sendfile.

* bpo-28075: Check for ERROR_ACCESS_DENIED in Windows implementation
  of os.stat().  Patch by Eryk Sun.

* bpo-22493: Warning message emitted by using inline flags in the
  middle of regular expression now contains a (truncated) regex
  pattern. Patch by Tim Graham.

* bpo-25270: Prevent codecs.escape_encode() from raising SystemError
  when an empty bytestring is passed.

* bpo-28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.

* bpo-25895: Enable WebSocket URL schemes in urllib.parse.urljoin.
  Patch by Gergely Imreh and Markus Holtermann.

* bpo-28114: Fix a crash in parse_envlist() when env contains byte
  strings. Patch by Eryk Sun.

* bpo-27599: Fixed buffer overrun in binascii.b2a_qp() and
  binascii.a2b_qp().

* bpo-27906: Fix socket accept exhaustion during high TCP traffic.
  Patch by Kevin Conway.

* bpo-28174: Handle when SO_REUSEPORT isn’t properly supported. Patch
  by Seth Michael Larson.

* bpo-26654: Inspect functools.partial in asyncio.Handle.__repr__.
  Patch by iceboy.

* bpo-26909: Fix slow pipes IO in asyncio. Patch by INADA Naoki.

* bpo-28176: Fix callbacks race in asyncio.SelectorLoop.sock_connect.

* bpo-27759: Fix selectors incorrectly retain invalid file
  descriptors. Patch by Mark Williams.

* bpo-28325: Remove vestigial MacOS 9 macurl2path module and its
  tests.

* bpo-28368: Refuse monitoring processes if the child watcher has no
  loop attached. Patch by Vincent Michel.

* bpo-28369: Raise RuntimeError when transport’s FD is used with
  add_reader, add_writer, etc.

* bpo-28370: Speedup asyncio.StreamReader.readexactly. Patch by
  Коренберг Марк.

* bpo-28371: Deprecate passing asyncio.Handles to run_in_executor.

* bpo-28372: Fix asyncio to support formatting of non-python
  coroutines.

* bpo-28399: Remove UNIX socket from FS before binding. Patch by
  Коренберг Марк.

* bpo-27972: Prohibit Tasks to await on themselves.

* bpo-24142: Reading a corrupt config file left configparser in an
  invalid state. Original patch by Florian Höch.

* bpo-29581: ABCMeta.__new__ now accepts "**kwargs", allowing abstract
  base classes to use keyword parameters in __init_subclass__. Patch
  by Nate Soares.

* bpo-25532: inspect.unwrap() will now only try to unwrap an object
  sys.getrecursionlimit() times, to protect against objects which
  create a new object on every attribute access.

* bpo-30177: path.resolve(strict=False) no longer cuts the path after
  the first element not present in the filesystem.  Patch by Antoine
  Pietri.


Documentation
-------------

* bpo-31294: Fix incomplete code snippet in the ZeroMQSocketListener
  and ZeroMQSocketHandler examples and adapt them to Python 3.

* bpo-21649: Add RFC 7525 and Mozilla server side TLS links to SSL
  documentation.

* bpo-31128: Allow the pydoc server to bind to arbitrary hostnames.

* bpo-30803: Clarify doc on truth value testing. Original patch by
  Peter Thomassen.

* bpo-30176: Add missing attribute related constants in curses
  documentation.

* bpo-30052: the link targets for "bytes()" and "bytearray()" are now
  their respective type definitions, rather than the corresponding
  builtin function entries. Use bytes and bytearray to reference the
  latter. In order to ensure this and future cross-reference updates
  are applied automatically, the daily documentation builds now
  disable the default output caching features in Sphinx.

* bpo-26985: Add missing info of code object in inspect documentation.

* bpo-19824: Improve the documentation for, and links to, template
  strings by emphasizing their utility for internationalization, and
  by clarifying some usage constraints. (See also: bpo-20314,
  bpo-12518)

* bpo-28929: Link the documentation to its source file on GitHub.

* bpo-25008: Document smtpd.py as effectively deprecated and add a
  pointer to aiosmtpd, a third-party asyncio-based replacement.

* bpo-26355: Add canonical header link on each page to corresponding
  major version of the documentation. Patch by Matthias Bussonnier.

* bpo-29349: Fix Python 2 syntax in code for building the
  documentation.

* bpo-23722: The data model reference and the porting section in the
  3.6 What’s New guide now cover the additional "__classcell__"
  handling needed for custom metaclasses to fully support **PEP 487**
  and zero-argument "super()".

* bpo-28513: Documented command-line interface of zipfile.


Tests
-----

* bpo-29639: test.support.HOST is now “localhost”, a new HOSTv4
  constant has been added for your "127.0.0.1" needs, similar to the
  existing HOSTv6 constant.

* bpo-31320: Silence traceback in test_ssl

* bpo-31346: Prefer PROTOCOL_TLS_CLIENT and PROTOCOL_TLS_SERVER
  protocols for SSLContext.

* bpo-25674: Remove sha256.tbs-internet.com ssl test

* bpo-30715: Address ALPN callback changes for OpenSSL 1.1.0f. The
  latest version behaves like OpenSSL 1.0.2 and no longer aborts
  handshake.

* bpo-30822: regrtest: Exclude tzdata from regrtest –all. When running
  the test suite using –use=all / -u all, exclude tzdata since it
  makes test_datetime too slow (15-20 min on some buildbots) which
  then times out on some buildbots. Fix also regrtest command line
  parser to allow passing -u extralargefile to run test_zipfile64.

* bpo-30695: Add the "set_nomemory(start, stop)" and
  "remove_mem_hooks()" functions to the _testcapi module.

* bpo-30357: test_thread: setUp() now uses support.threading_setup()
  and support.threading_cleanup() to wait until threads complete to
  avoid random side effects on following tests. Initial patch written
  by Grzegorz Grzywacz.

* bpo-30197: Enhanced functions swap_attr() and swap_item() in the
  test.support module. They now work when delete replaced attribute or
  item inside the with statement.  The old value of the attribute or
  item (or None if it doesn’t exist) now will be assigned to the
  target of the “as” clause, if there is one.

* bpo-24932: Use proper command line parsing in _testembed

* bpo-28950: Disallow -j0 to be combined with -T/-l in regrtest
  command line arguments.

* bpo-28683: Fix the tests that bind() a unix socket and raise
  PermissionError on Android for a non-root user.

* bpo-26936: Fix the test_socket failures on Android -
  getservbyname(), getservbyport() and getaddrinfo() are broken on
  some Android API levels.

* bpo-28666: Now test.support.rmtree is able to remove unwritable or
  unreadable directories.

* bpo-23839: Various caches now are cleared before running every test
  file.

* bpo-26944: Fix test_posix for Android where ‘id -G’ is entirely
  wrong or missing the effective gid.

* bpo-28409: regrtest: fix the parser of command line arguments.

* bpo-28217: Adds _testconsole module to test console input.

* bpo-26939: Add the support.setswitchinterval() function to fix
  test_functools hanging on the Android armv7 qemu emulator.


Build
-----

* bpo-31354: Allow –with-lto to be used on all builds, not just "make
  profile-opt".

* bpo-31370: Remove support for building –without-threads. This option
  is not really useful anymore in the 21st century. Removing lots of
  conditional paths allows us to simplify the code base, including in
  difficult to maintain low-level internal code.

* bpo-31341: Per **PEP 11**, support for the IRIX operating system was
  removed.

* bpo-30854: Fix compile error when compiling –without-threads. Patch
  by Masayuki Yamamoto.

* bpo-30687: Locate msbuild.exe on Windows when building rather than
  vcvarsall.bat

* bpo-20210: Support the *disabled* marker in Setup files. Extension
  modules listed after this marker are not built at all, neither by
  the Makefile nor by setup.py.

* bpo-29941: Add "--with-assertions" configure flag to explicitly
  enable C "assert()" checks. Defaults to off. "--with-pydebug"
  implies "--with-assertions".

* bpo-28787: Fix out-of-tree builds of Python when configured with "--
  with--dtrace".

* bpo-29243: Prevent unnecessary rebuilding of Python during "make
  test", "make install" and some other make targets when configured
  with "--enable-optimizations".

* bpo-23404: Don’t regenerate generated files based on file
  modification time anymore: the action is now explicit. Replace "make
  touch" with "make regen-all".

* bpo-29643: Fix "--enable-optimization" didn’t work.

* bpo-27593: sys.version and the platform module python_build(),
  python_branch(), and python_revision() functions now use git
  information rather than hg when building from a repo.

* bpo-29572: Update Windows build and OS X installers to use OpenSSL
  1.0.2k.

* bpo-27659: Prohibit implicit C function declarations: use "-Werror
  =implicit-function-declaration" when possible (GCC and Clang, but it
  depends on the compiler version). Patch written by Chi Hsuan Yen.

* bpo-29384: Remove old Be OS helper scripts.

* bpo-26851: Set Android compilation and link flags.

* bpo-28768: Fix implicit declaration of function _setmode. Patch by
  Masayuki Yamamoto

* bpo-29080: Removes hard dependency on hg.exe from PCBuild/build.bat

* bpo-23903: Added missed names to PC/python3.def.

* bpo-28762: lockf() is available on Android API level 24, but the
  F_LOCK macro is not defined in android-ndk-r13.

* bpo-28538: Fix the compilation error that occurs because
  if_nameindex() is available on Android API level 24, but the
  if_nameindex structure is not defined.

* bpo-20211: Do not add the directory for installing C header files
  and the directory for installing object code libraries to the cross
  compilation search paths. Original patch by Thomas Petazzoni.

* bpo-28849: Do not define sys.implementation._multiarch on Android.

* bpo-10656: Fix out-of-tree building on AIX.  Patch by Tristan Carel
  and Michael Haubenwallner.

* bpo-26359: Rename –with-optimiations to –enable-optimizations.

* bpo-28444: Fix missing extensions modules when cross compiling.

* bpo-28208: Update Windows build and OS X installers to use SQLite
  3.14.2.

* bpo-28248: Update Windows build and OS X installers to use OpenSSL
  1.0.2j.

* bpo-21124: Fix building the _struct module on Cygwin by passing
  "NULL" instead of "&PyType_Type" to PyVarObject_HEAD_INIT.  Patch by
  Masayuki Yamamoto.

* bpo-13756: Fix building extensions modules on Cygwin.  Patch by
  Roumen Petrov, based on original patch by Jason Tishler.

* bpo-21085: Add configure check for siginfo_t.si_band, which Cygwin
  does not provide. Patch by Masayuki Yamamoto with review and rebase
  by Erik Bray.

* bpo-28258: Fixed build with Estonian locale (python-config and
  distclean targets in Makefile).  Patch by Arfrever Frehtes Taifersar
  Arahesis.

* bpo-26661: setup.py now detects system libffi with multiarch
  wrapper.

* bpo-27979: A full copy of libffi is no longer bundled for use when
  building _ctypes on non-OSX UNIX platforms.  An installed copy of
  libffi is now required when building _ctypes on such platforms.

* bpo-15819: Remove redundant include search directory option for
  building outside the source tree.

* bpo-28676: Prevent missing ‘getentropy’ declaration warning on
  macOS. Patch by Gareth Rees.


Windows
-------

* bpo-31392: Update Windows build to use OpenSSL 1.1.0f

* bpo-30389: Adds detection of Visual Studio 2017 to distutils on
  Windows.

* bpo-31358: zlib is no longer bundled in the CPython source, instead
  it is downloaded on demand just like bz2, lzma, OpenSSL, Tcl/Tk, and
  SQLite.

* bpo-31340: Change to building with MSVC v141 (included with Visual
  Studio 2017)

* bpo-30581: os.cpu_count() now returns the correct number of
  processors on Windows when the number of logical processors is
  greater than 64.

* bpo-30916: Pre-build OpenSSL, Tcl and Tk and include the binaries in
  the build.

* bpo-30731: Add a missing xmlns to python.manifest so that it matches
  the schema.

* bpo-30291: Allow requiring 64-bit interpreters from py.exe using -64
  suffix. Contributed by Steve (Gadget) Barnes.

* bpo-30362: Adds list options (-0, -0p) to py.exe launcher.
  Contributed by Steve Barnes.

* bpo-23451: Fix socket deprecation warnings in socketmodule.c. Patch
  by Segev Finer.

* bpo-30450: The build process on Windows no longer depends on
  Subversion, instead pulling external code from GitHub via a Python
  script.  If Python 3.6 is not found on the system (via "py -3.6"),
  NuGet is used to download a copy of 32-bit Python.

* bpo-29579: Removes readme.txt from the installer.

* bpo-25778: winreg does not truncate string correctly (Patch by Eryk
  Sun)

* bpo-28896: Deprecate WindowsRegistryFinder and disable it by default

* bpo-28522: Fixes mishandled buffer reallocation in getpathp.c

* bpo-28402: Adds signed catalog files for stdlib on Windows.

* bpo-28333: Enables Unicode for ps1/ps2 and input() prompts. (Patch
  by Eryk Sun)

* bpo-28251: Improvements to help manuals on Windows.

* bpo-28110: launcher.msi has different product codes between 32-bit
  and 64-bit

* bpo-28161: Opening CON for write access fails

* bpo-28162: WindowsConsoleIO readall() fails if first line starts
  with Ctrl+Z

* bpo-28163: WindowsConsoleIO fileno() passes wrong flags to
  _open_osfhandle

* bpo-28164: _PyIO_get_console_type fails for various paths

* bpo-28137: Renames Windows path file to ._pth

* bpo-28138: Windows ._pth file should allow import site


IDLE
----

* bpo-31493: IDLE code context – fix code update and font update
  timers. Canceling timers prevents a warning message when test_idle
  completes.

* bpo-31488: IDLE - Update non-key options in former extension
  classes. When applying configdialog changes, call .reload for each
  feature class. Change ParenMatch so updated options affect existing
  instances attached to existing editor windows.

* bpo-31477: IDLE - Improve rstrip entry in doc. Strip trailing
  whitespace strips more than blank spaces.  Multiline string literals
  are not skipped.

* bpo-31480: IDLE - make tests pass with zzdummy extension disabled by
  default.

* bpo-31421: Document how IDLE runs tkinter programs. IDLE calls
  tcl/tk update in the background in order to make live interaction
  and experimentation with tkinter applications much easier.

* bpo-31414: IDLE – fix tk entry box tests by deleting first. Adding
  to an int entry is not the same as deleting and inserting because
  int(‘’) will fail.

* bpo-31051: Rearrange IDLE configdialog GenPage into Window, Editor,
  and Help sections.

* bpo-30617: IDLE - Add docstrings and tests for outwin subclass of
  editor. Move some data and functions from the class to module level.
  Patch by Cheryl Sabella.

* bpo-31287: IDLE - Do not modify tkinter.message in
  test_configdialog.

* bpo-27099: Convert IDLE’s built-in ‘extensions’ to regular features.
  About 10 IDLE features were implemented as supposedly optional
  extensions. Their different behavior could be confusing or worse for
  users and not good for maintenance. Hence the conversion. The main
  difference for users is that user configurable key bindings for
  builtin features are now handled uniformly. Now, editing a binding
  in a keyset only affects its value in the keyset. All bindings are
  defined together in the system-specific default keysets in config-
  extensions.def. All custom keysets are saved as a whole in config-
  extension.cfg.  All take effect as soon as one clicks Apply or Ok.
  The affected events are ‘<<force-open-completions>>’, ‘<<expand-
  word>>’, ‘<<force-open-calltip>>’, ‘<<flash-paren>>’, ‘<<format-
  paragraph>>’, ‘<<run-module>>’, ‘<<check-module>>’, and ‘<<zoom-
  height>>’.  Any (global) customizations made before 3.6.3 will not
  affect their keyset-specific customization after 3.6.3. and vice
  versa. Initial patch by Charles Wohlganger.

* bpo-31206: IDLE: Factor HighPage(Frame) class from ConfigDialog.
  Patch by Cheryl Sabella.

* bpo-31001: Add tests for configdialog highlight tab.  Patch by
  Cheryl Sabella.

* bpo-31205: IDLE: Factor KeysPage(Frame) class from ConfigDialog.
  The slightly modified tests continue to pass.  Patch by Cheryl
  Sabella.

* bpo-31130: IDLE – stop leaks in test_configdialog. Initial patch by
  Victor Stinner.

* bpo-31002: Add tests for configdialog keys tab. Patch by Cheryl
  Sabella.

* bpo-19903: IDLE: Calltips use "inspect.signature" instead of
  "inspect.getfullargspec". This improves calltips for builtins
  converted to use Argument Clinic. Patch by Louie Lu.

* bpo-31083: IDLE - Add an outline of a TabPage class in configdialog.
  Update existing classes to match outline. Initial patch by Cheryl
  Sabella.

* bpo-31050: Factor GenPage(Frame) class from ConfigDialog. The
  slightly modified tests continue to pass. Patch by Cheryl Sabella.

* bpo-31004: IDLE - Factor FontPage(Frame) class from ConfigDialog.
  Slightly modified tests continue to pass. Fix General tests. Patch
  mostly by Cheryl Sabella.

* bpo-30781: IDLE - Use ttk widgets in ConfigDialog. Patches by Terry
  Jan Reedy and Cheryl Sabella.

* bpo-31060: IDLE - Finish rearranging methods of ConfigDialog
  Grouping methods pertaining to each tab and the buttons will aid
  writing tests and improving the tabs and will enable splitting the
  groups into classes.

* bpo-30853: IDLE – Factor a VarTrace class out of ConfigDialog.
  Instance tracers manages pairs consisting of a tk variable and a
  callback function. When tracing is turned on, setting the variable
  calls the function.  Test coverage for the new class is 100%.

* bpo-31003: IDLE: Add more tests for General tab.

* bpo-30993: IDLE - Improve configdialog font page and tests. In
  configdialog: Document causal pathways in create_font_tab docstring.
  Simplify some attribute names. Move set_samples calls to
  var_changed_font (idea from Cheryl Sabella).  Move related functions
  to positions after the create widgets function. In
  test_configdialog: Fix test_font_set so not order dependent.  Fix
  renamed test_indent_scale so it tests the widget. Adjust tests for
  movement of set_samples call.  Add tests for load functions.  Put
  all font tests in one class and tab indent tests in another.  Except
  for two lines, these tests completely cover the related functions.

* bpo-30981: IDLE – Add more configdialog font page tests.

* bpo-28523: IDLE: replace ‘colour’ with ‘color’ in configdialog.

* bpo-30917: Add tests for idlelib.config.IdleConf. Increase coverage
  from 46% to 96%. Patch by Louie Lu.

* bpo-30934: Document coverage details for idlelib tests. Add section
  to idlelib/idle-test/README.txt. Include check that branches are
  taken both ways. Exclude IDLE-specific code that does not run during
  unit tests.

* bpo-30913: IDLE: Document ConfigDialog tk Vars, methods, and widgets
  in docstrings This will facilitate improving the dialog and
  splitting up the class. Original patch by Cheryl Sabella.

* bpo-30899: IDLE: Add tests for ConfigParser subclasses in config.
  Patch by Louie Lu.

* bpo-30881: IDLE: Add docstrings to browser.py. Patch by Cheryl
  Sabella.

* bpo-30851: IDLE: Remove unused variables in configdialog.  One is a
  duplicate, one is set but cannot be altered by users. Patch by
  Cheryl Sabella.

* bpo-30870: IDLE: In Settings dialog, select font with Up, Down keys
  as well as mouse. Initial patch by Louie Lu.

* bpo-8231: IDLE: call config.IdleConf.GetUserCfgDir only once.

* bpo-30779: IDLE: Factor ConfigChanges class from configdialog, put
  in config; test. * In config, put dump test code in a function; run
  it and unittest in   ‘if __name__ == ‘__main__’. * Add class
  config.ConfigChanges based on changes_class_v4.py on bpo issue. *
  Add class test_config.ChangesTest, partly using
  configdialog_tests_v1.py. * Revise configdialog to use
  ConfigChanges; see tracker msg297804. * Revise test_configdialog to
  match configdialog changes. * Remove configdialog functions unused
  or moved to ConfigChanges. Cheryl Sabella contributed parts of the
  patch.

* bpo-30777: IDLE: configdialog - Add docstrings and fix comments.
  Patch by Cheryl Sabella.

* bpo-30495: IDLE: Improve textview with docstrings, PEP8 names, and
  more tests. Patch by Cheryl Sabella.

* bpo-30723: IDLE: Make several improvements to parenmatch. Add
  ‘parens’ style to highlight both opener and closer. Make ‘default’
  style, which is not default, a synonym for ‘opener’. Make time-delay
  work the same with all styles. Add help for config dialog extensions
  tab, including help for parenmatch. Add new tests.  Original patch
  by Charles Wohlganger.

* bpo-30674: IDLE: add docstrings to grep module. Patch by Cheryl
  Sabella

* bpo-21519: IDLE’s basic custom key entry dialog now detects
  duplicates properly. Original patch by Saimadhav Heblikar.

* bpo-29910: IDLE no longer deletes a character after commenting out a
  region by a key shortcut.  Add "return 'break'" for this and other
  potential conflicts between IDLE and default key bindings.

* bpo-30728: Review and change idlelib.configdialog names. Lowercase
  method and attribute names. Replace ‘colour’ with ‘color’, expand
  overly cryptic names, delete unneeded underscores. Replace "import
  *" with specific imports. Patches by Cheryl Sabella.

* bpo-6739: IDLE: Verify user-entered key sequences by trying to bind
  them with tk. Add tests for all 3 validation functions. Original
  patch by G Polo.  Tests added by Cheryl Sabella.

* bpo-15786: Fix several problems with IDLE’s autocompletion box. The
  following should now work: clicking on selection box items; using
  the scrollbar; selecting an item by hitting Return. Hangs on MacOSX
  should no longer happen. Patch by Louie Lu.

* bpo-25514: Add doc subsubsection about IDLE failure to start. Popup
  no-connection message directs users to this section.

* bpo-30642: Fix reference leaks in IDLE tests. Patches by Louie Lu
  and Terry Jan Reedy.

* bpo-30495: Add docstrings for textview.py and use PEP8 names.
  Patches by Cheryl Sabella and Terry Jan Reedy.

* bpo-30290: Help-about: use pep8 names and add tests. Increase
  coverage to 100%. Patches by Louie Lu, Cheryl Sabella, and Terry Jan
  Reedy.

* bpo-30303: Add _utest option to textview; add new tests. Increase
  coverage to 100%. Patches by Louie Lu and Terry Jan Reedy.

* bpo-29071: IDLE colors f-string prefixes (but not invalid ur
  prefixes).

* bpo-28572: Add 10% to coverage of IDLE’s test_configdialog. Update
  and augment description of the configuration system.


Tools/Demos
-----------

* bpo-30983: gdb integration commands (py-bt, etc.) work on optimized
  shared builds now, too.  **PEP 523** introduced
  _PyEval_EvalFrameDefault which inlines PyEval_EvalFrameEx on non-
  debug shared builds.  This broke the ability to use py-bt, py-up,
  and a few other Python-specific gdb integrations. The problem is
  fixed by only looking for _PyEval_EvalFrameDefault frames in python-
  gdb.py.  Original patch by Bruno “Polaco” Penteado.

* bpo-29748: Added the slice index converter in Argument Clinic.

* bpo-24037: Argument Clinic now uses the converter
  "bool(accept={int})" rather than "int" for semantical booleans.
  This avoids repeating the default value for Python and C and will
  help in converting to "bool" in future.

* bpo-29367: python-gdb.py now supports also "method-wrapper"
  ("wrapperobject") objects.

* bpo-28023: Fix python-gdb.py didn’t support new dict implementation.

* bpo-15369: The pybench and pystone microbenchmark have been removed
  from Tools. Please use the new Python benchmark suite
  https://github.com/python/performance which is more reliable and
  includes a portable version of pybench working on Python 2 and
  Python 3.

* bpo-28102: The zipfile module CLI now prints usage to stderr. Patch
  by Stephen J. Turnbull.


C API
-----

* bpo-31338: Added the "Py_UNREACHABLE()" macro for code paths which
  are never expected to be reached.  This and a few other useful
  macros are now documented in the C API manual.

* bpo-30832: Remove own implementation for thread-local storage.
  CPython has provided the own implementation for thread-local storage
  (TLS) on Python/thread.c, it’s used in the case which a platform has
  not supplied native TLS.  However, currently all supported platforms
  (Windows and pthreads) have provided native TLS and defined the
  Py_HAVE_NATIVE_TLS macro with unconditional in any case.

* bpo-30708: PyUnicode_AsWideCharString() now raises a ValueError if
  the second argument is NULL and the wchar_t* string contains null
  characters.

* bpo-16500: Deprecate PyOS_AfterFork() and add PyOS_BeforeFork(),
  PyOS_AfterFork_Parent() and PyOS_AfterFork_Child().

* bpo-6532: The type of results of PyThread_start_new_thread() and
  PyThread_get_thread_ident(), and the id parameter of
  PyThreadState_SetAsyncExc() changed from “long” to “unsigned long”.

* bpo-27867: Function PySlice_GetIndicesEx() is deprecated and
  replaced with a macro if Py_LIMITED_API is not set or set to the
  value between 0x03050400 and 0x03060000 (not including) or
  0x03060100 or higher.  Added functions PySlice_Unpack() and
  PySlice_AdjustIndices().

* bpo-29083: Fixed the declaration of some public API functions.
  PyArg_VaParse() and PyArg_VaParseTupleAndKeywords() were not
  available in limited API. PyArg_ValidateKeywordArguments(),
  PyArg_UnpackTuple() and Py_BuildValue() were not available in
  limited API of version < 3.3 when PY_SSIZE_T_CLEAN is defined.

* bpo-28769: The result of PyUnicode_AsUTF8AndSize() and
  PyUnicode_AsUTF8() is now of type "const char *" rather of "char *".

* bpo-29058: All stable API extensions added after Python 3.2 are now
  available only when Py_LIMITED_API is set to the PY_VERSION_HEX
  value of the minimum Python version supporting this API.

* bpo-28822: The index parameters *start* and *end* of
  PyUnicode_FindChar() are now adjusted to behave like
  "str[start:end]".

* bpo-28808: PyUnicode_CompareWithASCIIString() now never raises
  exceptions.

* bpo-28761: The fields name and doc of structures PyMemberDef,
  PyGetSetDef, PyStructSequence_Field, PyStructSequence_Desc, and
  wrapperbase are now of type "const char *" rather of "char *".

* bpo-28748: Private variable _Py_PackageContext is now of type "const
  char *" rather of "char *".

* bpo-19569: Compiler warnings are now emitted if use most of
  deprecated functions.

* bpo-28426: Deprecated undocumented functions
  PyUnicode_AsEncodedObject(), PyUnicode_AsDecodedObject(),
  PyUnicode_AsDecodedUnicode() and PyUnicode_AsEncodedUnicode().


Python 3.6.6 final
==================

*Release date: 2018-06-27*

There were no new changes in version 3.6.6.


Python 3.6.6 release candidate 1
================================

*Release date: 2018-06-11*


Core and Builtins
-----------------

* bpo-33786: Fix asynchronous generators to handle GeneratorExit in
  athrow() correctly

* bpo-30654: Fixed reset of the SIGINT handler to SIG_DFL on
  interpreter shutdown even when there was a custom handler set
  previously. Patch by Philipp Kerling.

* bpo-33622: Fixed a leak when the garbage collector fails to add an
  object with the "__del__" method or referenced by it into the
  "gc.garbage" list. "PyGC_Collect()" can now be called when an
  exception is set and preserves it.

* bpo-31849: Fix signed/unsigned comparison warning in pyhash.c.

* bpo-33391: Fix a leak in set_symmetric_difference().

* bpo-28055: Fix unaligned accesses in siphash24(). Patch by Rolf Eike
  Beer.

* bpo-33231: Fix potential memory leak in "normalizestring()".

* bpo-29922: Improved error messages in ‘async with’ when
  "__aenter__()" or "__aexit__()" return non-awaitable object.

* bpo-33199: Fix "ma_version_tag" in dict implementation is
  uninitialized when copying from key-sharing dict.

* bpo-33041: Fixed jumping when the function contains an "async for"
  loop.

* bpo-32282: Fix an unnecessary ifdef in the include of
  VersionHelpers.h in socketmodule on Windows.

* bpo-21983: Fix a crash in "ctypes.cast()" in case the type argument
  is a ctypes structured data type. Patch by Eryk Sun and Oren Milman.


Library
-------

* bpo-30167: Prevent site.main() exception if PYTHONSTARTUP is set.
  Patch by Steve Weber.

* bpo-33812: Datetime instance d with non-None tzinfo, but with
  d.tzinfo.utcoffset(d) returning None is now treated as naive by the
  astimezone() method.

* bpo-30805: Avoid race condition with debug logging

* bpo-33767: The concatenation ("+") and repetition ("*") sequence
  operations now raise "TypeError" instead of "SystemError" when
  performed on "mmap.mmap" objects.  Patch by Zackery Spytz.

* bpo-32684: Fix gather to propagate cancellation of itself even with
  return_exceptions.

* bpo-33674: Fix a race condition in SSLProtocol.connection_made() of
  asyncio.sslproto: start immediately the handshake instead of using
  call_soon(). Previously, data_received() could be called before the
  handshake started, causing the handshake to hang or fail.

* bpo-31647: Fixed bug where calling write_eof() on a
  _SelectorSocketTransport after it’s already closed raises
  AttributeError.

* bpo-33672: Fix Task.__repr__ crash with Cython’s bogus coroutines

* bpo-33469: Fix RuntimeError after closing loop that used
  run_in_executor

* bpo-11874: Use a better regex when breaking usage into wrappable
  parts. Avoids bogus assertion errors from custom metavar strings.

* bpo-30877: Fixed a bug in the Python implementation of the JSON
  decoder that prevented the cache of parsed strings from clearing
  after finishing the decoding. Based on patch by c-fos.

* bpo-33548: tempfile._candidate_tempdir_list should consider common
  TEMP locations

* bpo-33542: Prevent "uuid.get_node" from using a DUID instead of a
  MAC on Windows. Patch by Zvi Effron

* bpo-26819: Fix race condition with "ReadTransport.resume_reading" in
  Windows proactor event loop.

* bpo-28556: Minor fixes in typing module: add annotations to
  "NamedTuple.__new__", pass "*args" and "**kwds" in
  "Generic.__new__".  Original PRs by Paulius Šarka and Chad Dombrova.

* bpo-20087: Updated alias mapping with glibc 2.27 supported locales.

* bpo-33422: Fix trailing quotation marks getting deleted when looking
  up byte/string literals on pydoc. Patch by Andrés Delfino.

* bpo-33197: Update error message when constructing invalid
  inspect.Parameters Patch by Dong-hee Na.

* bpo-33383: Fixed crash in the get() method of the "dbm.ndbm"
  database object when it is called with a single argument.

* bpo-33329: Fix multiprocessing regression on newer glibcs

* bpo-991266: Fix quoting of the "Comment" attribute of
  "http.cookies.SimpleCookie".

* bpo-33131: Upgrade bundled version of pip to 10.0.1.

* bpo-33308: Fixed a crash in the "parser" module when converting an
  ST object to a tree of tuples or lists with "line_info=False" and
  "col_info=True".

* bpo-33263: Fix FD leak in "_SelectorSocketTransport"  Patch by Vlad
  Starostin.

* bpo-33256: Fix display of "<module>" call in the html produced by
  "cgitb.html()". Patch by Stéphane Blondon.

* bpo-33203: "random.Random.choice()" now raises "IndexError" for
  empty sequences consistently even when called from subclasses
  without a "getrandbits()" implementation.

* bpo-33224: Update difflib.mdiff() for **PEP 479**.  Convert an
  uncaught StopIteration in a generator into a return-statement.

* bpo-33209: End framing at the end of C implementation of
  "pickle.Pickler.dump()".

* bpo-32861: The urllib.robotparser’s "__str__" representation now
  includes wildcard entries and the “Crawl-delay” and “Request-rate”
  fields. Patch by Michael Lazar.

* bpo-33096: Allow ttk.Treeview.insert to insert iid that has a false
  boolean value. Note iid=0 and iid=False would be same. Patch by
  Garvit Khatri.

* bpo-33127: The ssl module now compiles with LibreSSL 2.7.1.

* bpo-33021: Release the GIL during fstat() calls, avoiding hang of
  all threads when calling mmap.mmap(), os.urandom(), and
  random.seed().  Patch by Nir Soffer.

* bpo-27683: Fix a regression in "ipaddress" that result of "hosts()"
  is empty when the network is constructed by a tuple containing an
  integer mask and only 1 bit left for addresses.

* bpo-32844: Fix wrong redirection of a low descriptor (0 or 1) to
  stderr in subprocess if another low descriptor is closed.

* bpo-31908: Fix output of cover files for "trace" module command-line
  tool. Previously emitted cover files only when "--missing" option
  was used. Patch by Michael Selik.

* bpo-31457: If nested log adapters are used, the inner "process()"
  methods are no longer omitted.

* bpo-16865: Support arrays >=2GiB in "ctypes".  Patch by Segev Finer.

* bpo-31238: pydoc: the stop() method of the private ServerThread
  class now waits until DocServer.serve_until_quit() completes and
  then explicitly sets its docserver attribute to None to break a
  reference cycle.


Documentation
-------------

* bpo-33503: Fix broken pypi link

* bpo-33421: Add missing documentation for
  "typing.AsyncContextManager".

* bpo-33378: Add Korean language switcher for
  https://docs.python.org/3/

* bpo-33276: Clarify that the "__path__" attribute on modules cannot
  be just any value.

* bpo-33201: Modernize documentation for writing C extension types.

* bpo-33195: Deprecate "Py_UNICODE" usage in "c-api/arg" document.
  "Py_UNICODE" related APIs are deprecated since Python 3.3, but it is
  missed in the document.

* bpo-33126: Document PyBuffer_ToContiguous().

* bpo-27212: Modify documentation for the "islice()" recipe to consume
  initial values up to the start index.

* bpo-28247: Update "zipapp" documentation to describe how to make
  standalone applications.

* bpo-18802: Documentation changes for ipaddress.  Patch by Jon Foster
  and Berker Peksag.

* bpo-27428: Update documentation to clarify that
  "WindowsRegistryFinder" implements "MetaPathFinder". (Patch by
  Himanshu Lakhara)

* bpo-8243: Add a note about curses.addch and curses.addstr exception
  behavior when writing outside a window, or pad.

* bpo-31432: Clarify meaning of CERT_NONE, CERT_OPTIONAL, and
  CERT_REQUIRED flags for ssl.SSLContext.verify_mode.


Tests
-----

* bpo-33655: Ignore test_posix_fallocate failures on BSD platforms
  that might be due to running on ZFS.

* bpo-19417: Add test_bdb.py.


Build
-----

* bpo-5755: Move "-Wstrict-prototypes" option to "CFLAGS_NODIST" from
  "OPT". This option emitted annoying warnings when building extension
  modules written in C++.

* bpo-33614: Ensures module definition files for the stable ABI on
  Windows are correctly regenerated.

* bpo-33522: Enable CI builds on Visual Studio Team Services at
  https://python.visualstudio.com/cpython

* bpo-33012: Add "-Wno-cast-function-type" for gcc 8 for silencing
  warnings about function casts like casting to PyCFunction in method
  definition lists.

* bpo-33394: Enable the verbose build for extension modules, when GNU
  make is passed macros on the command line.


Windows
-------

* bpo-33184: Update Windows installer to OpenSSL 1.0.2o.


macOS
-----

* bpo-33184: Update macOS installer build to use OpenSSL 1.0.2o.


IDLE
----

* bpo-33656: On Windows, add API call saying that tk scales for DPI.
  On Windows 8.1+ or 10, with DPI compatibility properties of the
  Python binary unchanged, and a monitor resolution greater than 96
  DPI, this should make text and lines sharper.  It should otherwise
  have no effect.

* bpo-33768: Clicking on a context line moves that line to the top of
  the editor window.

* bpo-33763: IDLE: Use read-only text widget for code context instead
  of label widget.

* bpo-33664: Scroll IDLE editor text by lines. Previously, the mouse
  wheel and scrollbar slider moved text by a fixed number of pixels,
  resulting in partial lines at the top of the editor box.  The change
  also applies to the shell and grep output windows, but not to read-
  only text views.

* bpo-33679: Enable theme-specific color configuration for Code
  Context. Use the Highlights tab to see the setting for built-in
  themes or add settings to custom themes.

* bpo-33642: Display up to maxlines non-blank lines for Code Context.
  If there is no current context, show a single blank line.

* bpo-33628: IDLE: Cleanup codecontext.py and its test.

* bpo-33564: IDLE’s code context now recognizes async as a block
  opener.

* bpo-29706: IDLE now colors async and await as keywords in 3.6. They
  become full keywords in 3.7.

* bpo-21474: Update word/identifier definition from ascii to unicode.
  In text and entry boxes, this affects selection by double-click,
  movement left/right by control-left/right, and deletion left/right
  by control-BACKSPACE/DEL.

* bpo-33204: IDLE: consistently color invalid string prefixes. A ‘u’
  string prefix cannot be paired with either ‘r’ or ‘f’. Consistently
  color as much of the prefix, starting at the right, as is valid.
  Revise and extend colorizer test.

* bpo-32831: Add docstrings and tests for codecontext.


Tools/Demos
-----------

* bpo-33189: **pygettext.py** now recognizes only literal strings as
  docstrings and translatable strings, and rejects bytes literals and
  f-string expressions.

* bpo-31920: Fixed handling directories as arguments in the
  "pygettext" script. Based on patch by Oleg Krasnikov.

* bpo-29673: Fix pystackv and pystack gdbinit macros.

* bpo-32885: Add an "-n" flag for "Tools/scripts/pathfix.py" to
  disable automatic backup creation (files with "~" suffix).

* bpo-31583: Fix 2to3 for using with –add-suffix option but without
  –output-dir option for relative path to files in current directory.


C API
-----

* bpo-32374: Document that m_traverse for multi-phase initialized
  modules can be called with m_state=NULL, and add a sanity check


Python 3.6.5 final
==================

*Release date: 2018-03-28*


Tests
-----

* bpo-32872: Avoid regrtest compatibility issue with namespace
  packages.


Build
-----

* bpo-33163: Upgrade pip to 9.0.3 and setuptools to v39.0.1.


Python 3.6.5 release candidate 1
================================

*Release date: 2018-03-13*


Security
--------

* bpo-33001: Minimal fix to prevent buffer overrun in os.symlink on
  Windows

* bpo-32981: Regexes in difflib and poplib were vulnerable to
  catastrophic backtracking. These regexes formed potential DOS
  vectors (REDOS). They have been refactored. This resolves
  CVE-2018-1060 and CVE-2018-1061. Patch by Jamie Davis.


Core and Builtins
-----------------

* bpo-33026: Fixed jumping out of “with” block by setting f_lineno.

* bpo-17288: Prevent jumps from ‘return’ and ‘exception’ trace events.

* bpo-32889: Update Valgrind suppression list to account for the
  rename of "Py_ADDRESS_IN_RANG" to "address_in_range".

* bpo-32650: Pdb and other debuggers dependent on bdb.py will
  correctly step over (next command) native coroutines. Patch by Pablo
  Galindo.

* bpo-32685: Improve suggestion when the Python 2 form of print
  statement is either present on the same line as the header of a
  compound statement or else terminated by a semi-colon instead of a
  newline. Patch by Nitish Chandra.

* bpo-32583: Fix possible crashing in builtin Unicode decoders caused
  by write out-of-bound errors when using customized decode error
  handlers.

* bpo-26163: Improved frozenset() hash to create more distinct hash
  values when faced with datasets containing many similar values.

* bpo-27169: The "__debug__" constant is now optimized out at compile
  time. This fixes also bpo-22091.

* bpo-32329: "sys.flags.hash_randomization" is now properly set to 0
  when hash randomization is turned off by "PYTHONHASHSEED=0".

* bpo-30416: The optimizer is now protected from spending much time
  doing complex calculations and consuming much memory for creating
  large constants in constant folding.

* bpo-18533: "repr()" on a dict containing its own "values()" or
  "items()" no longer raises "RecursionError"; OrderedDict similarly.
  Instead, use "...", as for other recursive structures.  Patch by Ben
  North.

* bpo-32028: Leading whitespace is now correctly ignored when
  generating suggestions for converting Py2 print statements to Py3
  builtin print function calls. Patch by Sanyam Khurana.

* bpo-32137: The repr of deeply nested dict now raises a
  RecursionError instead of crashing due to a stack overflow.


Library
-------

* bpo-33064: lib2to3 now properly supports trailing commas after
  "*args" and "**kwargs" in function signatures.

* bpo-31804: Avoid failing in multiprocessing.Process if the standard
  streams are closed or None at exit.

* bpo-33037: Skip sending/receiving data after SSL transport closing.

* bpo-30353: Fix ctypes pass-by-value for structs on 64-bit
  Cygwin/MinGW.

* bpo-33009: Fix inspect.signature() for single-parameter
  partialmethods.

* bpo-32969: Expose several missing constants in zlib and fix
  corresponding documentation.

* bpo-32713: Fixed tarfile.itn handling of out-of-bounds float values.
  Patch by Joffrey Fuhrer.

* bpo-30622: The ssl module now detects missing NPN support in
  LibreSSL.

* bpo-32922: dbm.open() now encodes filename with the filesystem
  encoding rather than default encoding.

* bpo-32859: In "os.dup2", don’t check every call whether the "dup3"
  syscall exists or not.

* bpo-21060: Rewrite confusing message from setup.py upload from “No
  dist file created in earlier command” to the more helpful “Must
  create and upload files in one command”.

* bpo-32857: In "tkinter", "after_cancel(None)" now raises a
  "ValueError" instead of canceling the first scheduled function.
  Patch by Cheryl Sabella.

* bpo-32852: Make sure sys.argv remains as a list when running trace.

* bpo-32841: Fixed "asyncio.Condition" issue which silently ignored
  cancellation after notifying and cancelling a conditional lock.
  Patch by Bar Harel.

* bpo-31787: Fixed refleaks of "__init__()" methods in various
  modules. (Contributed by Oren Milman)

* bpo-30157: Fixed guessing quote and delimiter in csv.Sniffer.sniff()
  when only the last field is quoted.  Patch by Jake Davis.

* bpo-32394: socket: Remove TCP_FASTOPEN, TCP_KEEPCNT flags on older
  version Windows during run-time.

* bpo-32777: Fix a rare but potential pre-exec child process deadlock
  in subprocess on POSIX systems when marking file descriptors
  inheritable on exec in the child process.  This bug appears to have
  been introduced in 3.4.

* bpo-32647: The ctypes module used to depend on indirect linking for
  dlopen. The shared extension is now explicitly linked against libdl
  on platforms with dl.

* bpo-32734: Fixed "asyncio.Lock()" safety issue which allowed
  acquiring and locking the same lock multiple times, without it being
  free. Patch by Bar Harel.

* bpo-32727: Do not include name field in SMTP envelope from address.
  Patch by Stéphane Wirtel

* bpo-27931: Fix email address header parsing error when the username
  is an empty quoted string. Patch by Xiang Zhang.

* bpo-32304: distutils’ upload command no longer corrupts tar files
  ending with a CR byte, and no longer tries to convert CR to CRLF in
  any of the upload text fields.

* bpo-32502: uuid.uuid1 no longer raises an exception if a 64-bit
  hardware address is encountered.

* bpo-31848: Fix the error handling in Aifc_read.initfp() when the
  SSND chunk is not found. Patch by Zackery Spytz.

* bpo-32555: On FreeBSD and Solaris, os.strerror() now always decode
  the byte string from the current locale encoding, rather than using
  ASCII/surrogateescape in some cases.

* bpo-32521: The nis module is now compatible with new libnsl and
  headers location.

* bpo-32473: Improve ABCMeta._dump_registry() output readability

* bpo-32521: glibc has removed Sun RPC. Use replacement libtirpc
  headers and library in nis module.

* bpo-32228: Ensure that "truncate()" preserves the file position (as
  reported by "tell()") after writes longer than the buffer size.

* bpo-26133: Don’t unsubscribe signals in asyncio UNIX event loop on
  interpreter shutdown.

* bpo-32185: The SSL module no longer sends IP addresses in SNI TLS
  extension on platforms with OpenSSL 1.0.2+ or inet_pton.

* bpo-32323: "urllib.parse.urlsplit()" does not convert zone-id
  (scope) to lower case for scoped IPv6 addresses in hostnames now.

* bpo-32302: Fix bdist_wininst of distutils for CRT v142: it binary
  compatible with CRT v140.

* bpo-32255: A single empty field is now always quoted when written
  into a CSV file. This allows to distinguish an empty row from a row
  consisting of a single empty field. Patch by Licht Takeuchi.

* bpo-32277: Raise "NotImplementedError" instead of "SystemError" on
  platforms where "chmod(..., follow_symlinks=False)" is not
  supported. Patch by Anthony Sottile.

* bpo-32199: The getnode() ip getter now uses ‘ip link’ instead of ‘ip
  link list’.

* bpo-27456: Ensure TCP_NODELAY is set on Linux. Tests by Victor
  Stinner.

* bpo-31900: The "locale.localeconv()" function now sets temporarily
  the "LC_CTYPE" locale to the "LC_NUMERIC" locale to decode
  "decimal_point" and "thousands_sep" byte strings if they are non-
  ASCII or longer than 1 byte, and the "LC_NUMERIC" locale is
  different than the "LC_CTYPE" locale. This temporary change affects
  other threads. Same change for the "str.format()" method when
  formatting a number ("int", "float", "float" and subclasses) with
  the "n" type (ex: "'{:n}'.format(1234)").

* bpo-31802: Importing native path module ("posixpath", "ntpath") now
  works even if the "os" module still is not imported.


Documentation
-------------

* bpo-17232: Clarify docs for -O and -OO.  Patch by Terry Reedy.

* bpo-32800: Update link to w3c doc for xml default namespaces.

* bpo-8722: Document "__getattr__()" behavior when property "get()"
  method raises "AttributeError".

* bpo-32614: Modify RE examples in documentation to use raw strings to
  prevent "DeprecationWarning" and add text to REGEX HOWTO to
  highlight the deprecation.

* bpo-31972: Improve docstrings for "pathlib.PurePath" subclasses.

* bpo-17799: Explain real behaviour of sys.settrace and sys.setprofile
  and their C-API counterparts regarding which type of events are
  received in each function. Patch by Pablo Galindo Salgado.


Tests
-----

* bpo-32517: Fix failing "test_asyncio" on macOS 10.12.2+ due to
  transport of "KqueueSelector" loop was not being closed.

* bpo-32721: Fix test_hashlib to not fail if the _md5 module is not
  built.

* bpo-32252: Fix faulthandler_suppress_crash_report() used to prevent
  core dump files when testing crashes. getrlimit() returns zero on
  success.

* bpo-31518: Debian Unstable has disabled TLS 1.0 and 1.1 for
  SSLv23_METHOD(). Change TLS/SSL protocol of some tests to
  PROTOCOL_TLS or PROTOCOL_TLSv1_2 to make them pass on Debian.


Build
-----

* bpo-32635: Fix segfault of the crypt module when libxcrypt is
  provided instead of libcrypt at the system.


Windows
-------

* bpo-33016: Fix potential use of uninitialized memory in
  nt._getfinalpathname

* bpo-32903: Fix a memory leak in os.chdir() on Windows if the current
  directory is set to a UNC path.

* bpo-31966: Fixed WindowsConsoleIO.write() for writing empty data.

* bpo-32409: Ensures activate.bat can handle Unicode contents.

* bpo-32457: Improves handling of denormalized executable path when
  launching Python.

* bpo-32370: Use the correct encoding for ipconfig output in the uuid
  module. Patch by Segev Finer.

* bpo-29248: Fix "os.readlink()" on Windows, which was mistakenly
  treating the "PrintNameOffset" field of the reparse data buffer as a
  number of characters instead of bytes. Patch by Craig Holmquist and
  SSE4.

* bpo-32588: Create standalone _distutils_findvs module.


macOS
-----

* bpo-32726: Provide an additional, more modern macOS installer
  variant that supports macOS 10.9+ systems in 64-bit mode only.
  Upgrade the supplied third-party libraries to OpenSSL 1.0.2n, XZ
  5.2.3, and SQLite 3.22.0. The 10.9+ installer now links with and
  supplies its own copy of Tcl/Tk 8.6.8.


IDLE
----

* bpo-32984: Set "__file__" while running a startup file.  Like
  Python, IDLE optionally runs one startup file in the Shell window
  before presenting the first interactive input prompt.  For IDLE,
  "-s" runs a file named in environmental variable  "IDLESTARTUP" or
  "PYTHONSTARTUP"; "-r file" runs "file".  Python sets "__file__" to
  the startup file name before running the file and unsets it before
  the first prompt.  IDLE now does the same when run normally, without
  the "-n" option.

* bpo-32940: Simplify and rename StringTranslatePseudoMapping in
  pyparse.

* bpo-32916: Change "str" to "code" in pyparse.

* bpo-32905: Remove unused code in pyparse module.

* bpo-32874: Add tests for pyparse.

* bpo-32837: Using the system and place-dependent default encoding for
  open() is a bad idea for IDLE’s system and location-independent
  files.

* bpo-32826: Add “encoding=utf-8” to open() in IDLE’s test_help_about.
  GUI test test_file_buttons() only looks at initial ascii-only lines,
  but failed on systems where open() defaults to ‘ascii’ because
  readline() internally reads and decodes far enough ahead to
  encounter a non-ascii character in CREDITS.txt.

* bpo-32765: Update configdialog General tab docstring to add new
  widgets to the widget list.


Tools/Demos
-----------

* bpo-24960: 2to3 and lib2to3 can now read pickled grammar files using
  pkgutil.get_data() rather than probing the filesystem. This lets
  2to3 and lib2to3 work when run from a zipfile.

* bpo-32222: Fix pygettext not extracting docstrings for functions
  with type annotated arguments. Patch by Toby Harradine.


C API
-----

* bpo-29084: Undocumented C API for OrderedDict has been excluded from
  the limited C API. It was added by mistake and actually never worked
  in the limited C API.


Python 3.6.4 final
==================

*Release date: 2017-12-18*

There were no new code changes in version 3.6.4 since v3.6.4rc1.


Python 3.6.4 release candidate 1
================================

*Release date: 2017-12-05*


Core and Builtins
-----------------

* bpo-32176: co_flags.CO_NOFREE is now always set correctly by the
  code object constructor based on freevars and cellvars, rather than
  needing to be set correctly by the caller. This ensures it will be
  cleared automatically when additional cell references are injected
  into a modified code object and function.

* bpo-31949: Fixed several issues in printing tracebacks
  (PyTraceBack_Print()). Setting sys.tracebacklimit to 0 or less now
  suppresses printing tracebacks. Setting sys.tracebacklimit to None
  now causes using the default limit. Setting sys.tracebacklimit to an
  integer larger than LONG_MAX now means using the limit LONG_MAX
  rather than the default limit. Fixed integer overflows in the case
  of more than "2**31" traceback items on Windows. Fixed output errors
  handling.

* bpo-30696: Fix the interactive interpreter looping endlessly when no
  memory.

* bpo-20047: Bytearray methods partition() and rpartition() now accept
  only bytes-like objects as separator, as documented.  In particular
  they now raise TypeError rather of returning a bogus result when an
  integer is passed as a separator.

* bpo-31852: Fix a segmentation fault caused by a combination of the
  async soft keyword and continuation lines.

* bpo-21720: BytesWarning no longer emitted when the *fromlist*
  argument of "__import__()" or the "__all__" attribute of the module
  contain bytes instances.

* bpo-31825: Fixed OverflowError in the ‘unicode-escape’ codec and in
  codecs.escape_decode() when decode an escaped non-ascii byte.

* bpo-28603: Print the full context/cause chain of exceptions on
  interpreter exit, even if an exception in the chain is unhashable or
  compares equal to later ones. Patch by Zane Bitter.

* bpo-31786: Fix timeout rounding in the select module to round
  correctly negative timeouts between -1.0 and 0.0. The functions now
  block waiting for events as expected. Previously, the call was
  incorrectly non-blocking. Patch by Pablo Galindo.

* bpo-31642: Restored blocking “from package import module” by setting
  sys.modules[“package.module”] to None.

* bpo-31626: Fixed a bug in debug memory allocator.  There was a write
  to freed memory after shrinking a memory block.

* bpo-31619: Fixed a ValueError when convert a string with large
  number of underscores to integer with binary base.

* bpo-31592: Fixed an assertion failure in Python parser in case of a
  bad "unicodedata.normalize()". Patch by Oren Milman.

* bpo-31588: Raise a "TypeError" with a helpful error message when
  class creation fails due to a metaclass with a bad "__prepare__()"
  method. Patch by Oren Milman.

* bpo-31566: Fix an assertion failure in "_warnings.warn()" in case of
  a bad "__name__" global. Patch by Oren Milman.

* bpo-31505: Fix an assertion failure in "json", in case
  "_json.make_encoder()" received a bad "encoder()" argument. Patch by
  Oren Milman.

* bpo-31492: Fix assertion failures in case of failing to import from
  a module with a bad "__name__" attribute, and in case of failing to
  access an attribute of such a module. Patch by Oren Milman.

* bpo-31490: Fix an assertion failure in "ctypes" class definition, in
  case the class has an attribute whose name is specified in
  "_anonymous_" but not in "_fields_". Patch by Oren Milman.

* bpo-31478: Fix an assertion failure in "_random.Random.seed()" in
  case the argument has a bad "__abs__()" method. Patch by Oren
  Milman.

* bpo-31315: Fix an assertion failure in imp.create_dynamic(), when
  spec.name is not a string. Patch by Oren Milman.

* bpo-31311: Fix a crash in the "__setstate__()" method of
  "ctypes._CData", in case of a bad "__dict__". Patch by Oren Milman.

* bpo-31293: Fix crashes in true division and multiplication of a
  timedelta object by a float with a bad as_integer_ratio() method.
  Patch by Oren Milman.

* bpo-31285: Fix an assertion failure in "warnings.warn_explicit",
  when the return value of the received loader’s get_source() has a
  bad splitlines() method. Patch by Oren Milman.

* bpo-30817: "PyErr_PrintEx()" clears now the ignored exception that
  may be raised by "_PySys_SetObjectId()", for example when no memory.


Library
-------

* bpo-28556: Two minor fixes for "typing" module: allow shallow
  copying instances of generic classes, improve interaction of
  "__init_subclass__" with generics. Original PRs by Ivan Levkivskyi.

* bpo-27240: The header folding algorithm for the new email policies
  has been rewritten, which also fixes bpo-30788, bpo-31831, and
  bpo-32182.  In particular, RFC2231 folding is now done correctly.

* bpo-32186: io.FileIO.readall() and io.FileIO.read() now release the
  GIL when getting the file size. Fixed hang of all threads with
  inaccessible NFS server. Patch by Nir Soffer.

* bpo-12239: Make "msilib.SummaryInformation.GetProperty()" return
  "None" when the value of property is "VT_EMPTY".  Initial patch by
  Mark Mc Mahon.

* bpo-31325: Fix wrong usage of "collections.namedtuple()" in the
  "RobotFileParser.parse()" method. Initial patch by Robin Wellner.

* bpo-12382: "msilib.OpenDatabase()" now raises a better exception
  message when it couldn’t open or create an MSI file.  Initial patch
  by William Tisäter.

* bpo-32110: "codecs.StreamReader.read(n)" now returns not more than
  *n* characters/bytes for non-negative *n*. This makes it compatible
  with "read()" methods of other file-like objects.

* bpo-32072: Fixed issues with binary plists: Fixed saving bytearrays.
  Identical objects will be saved only once. Equal references will be
  load as identical objects. Added support for saving and loading
  recursive data structures.

* bpo-32034: Make asyncio.IncompleteReadError and LimitOverrunError
  pickleable.

* bpo-32015: Fixed the looping of asyncio in the case of reconnection
  the socket during waiting async read/write from/to the socket.

* bpo-32011: Restored support of loading marshal files with the
  TYPE_INT64 code. These files can be produced in Python 2.7.

* bpo-31970: Reduce performance overhead of asyncio debug mode.

* bpo-9678: Fixed determining the MAC address in the uuid module:
  Using ifconfig on NetBSD and OpenBSD. Using arp on Linux, FreeBSD,
  NetBSD and OpenBSD. Based on patch by Takayuki Shimizukawa.

* bpo-30057: Fix potential missed signal in signal.signal().

* bpo-31933: Fix Blake2 params leaf_size and node_offset on big endian
  platforms. Patch by Jack O’Connor.

* bpo-31927: Fixed compilation of the socket module on NetBSD 8.
  Fixed assertion failure or reading arbitrary data when parse a
  AF_BLUETOOTH address on NetBSD and DragonFly BSD.

* bpo-27666: Fixed stack corruption in curses.box() and
  curses.ungetmouse() when the size of types chtype or mmask_t is less
  than the size of C long. curses.box() now accepts characters as
  arguments.  Based on patch by Steve Fink.

* bpo-31897: plistlib now catches more errors when read binary plists
  and raises InvalidFileException instead of unexpected exceptions.

* bpo-25720: Fix the method for checking pad state of curses WINDOW.
  Patch by Masayuki Yamamoto.

* bpo-31893: Fixed the layout of the kqueue_event structure on OpenBSD
  and NetBSD. Fixed the comparison of the kqueue_event objects.

* bpo-31891: Fixed building the curses module on NetBSD.

* bpo-28416: Instances of pickle.Pickler subclass with the
  persistent_id() method and pickle.Unpickler subclass with the
  persistent_load() method no longer create reference cycles.

* bpo-28326: Fix multiprocessing.Process when stdout and/or stderr is
  closed or None.

* bpo-31457: If nested log adapters are used, the inner "process()"
  methods are no longer omitted.

* bpo-31457: The "manager" property on LoggerAdapter objects is now
  properly settable.

* bpo-31806: Fix timeout rounding in time.sleep(),
  threading.Lock.acquire() and socket.socket.settimeout() to round
  correctly negative timeouts between -1.0 and 0.0. The functions now
  block waiting for events as expected. Previously, the call was
  incorrectly non-blocking. Patch by Pablo Galindo.

* bpo-28603: traceback: Fix a TypeError that occurred during printing
  of exception tracebacks when either the current exception or an
  exception in its context/cause chain is unhashable. Patch by Zane
  Bitter.

* bpo-30058: Fixed buffer overflow in select.kqueue.control().

* bpo-31770: Prevent a crash when calling the "__init__()" method of a
  "sqlite3.Cursor" object more than once. Patch by Oren Milman.

* bpo-31672: "idpattern" in "string.Template" matched some non-ASCII
  characters. Now it uses "-i" regular expression local flag to avoid
  non-ASCII characters.

* bpo-31764: Prevent a crash in "sqlite3.Cursor.close()" in case the
  "Cursor" object is uninitialized. Patch by Oren Milman.

* bpo-31752: Fix possible crash in timedelta constructor called with
  custom integers.

* bpo-31701: On Windows, faulthandler.enable() now ignores MSC and COM
  exceptions.

* bpo-31728: Prevent crashes in "_elementtree" due to unsafe cleanup
  of "Element.text" and "Element.tail". Patch by Oren Milman.

* bpo-31620: an empty asyncio.Queue now doesn’t leak memory when
  queue.get pollers timeout

* bpo-31632: Fix method set_protocol() of class _SSLProtocolTransport
  in asyncio module. This method was previously modifying a wrong
  reference to the protocol.

* bpo-31675: Fixed memory leaks in Tkinter’s methods splitlist() and
  split() when pass a string larger than 2 GiB.

* bpo-31673: Fixed typo in the name of Tkinter’s method
  adderrorinfo().

* bpo-30806: Fix the string representation of a netrc object.

* bpo-15037: Added a workaround for getkey() in curses for ncurses 5.7
  and earlier.

* bpo-25351: Avoid venv activate failures with undefined variables

* bpo-25532: inspect.unwrap() will now only try to unwrap an object
  sys.getrecursionlimit() times, to protect against objects which
  create a new object on every attribute access.

* bpo-30347: Stop crashes when concurrently iterate over
  itertools.groupby() iterators.

* bpo-31516: "threading.current_thread()" should not return a dummy
  thread at shutdown.

* bpo-31351: python -m ensurepip now exits with non-zero exit code if
  pip bootstrapping has failed.

* bpo-31482: "random.seed()" now works with bytes in version=1

* bpo-31334: Fix "poll.poll([timeout])" in the "select" module for
  arbitrary negative timeouts on all OSes where it can only be a non-
  negative integer or -1. Patch by Riccardo Coccioli.

* bpo-31310: multiprocessing’s semaphore tracker should be launched
  again if crashed.

* bpo-31308: Make multiprocessing’s forkserver process immune to
  Ctrl-C and other user interruptions. If it crashes, restart it when
  necessary.


Documentation
-------------

* bpo-32105: Added asyncio.BaseEventLoop.connect_accepted_socket
  versionadded marker.

* bpo-31537: Fix incorrect usage of "get_history_length" in readline
  documentation example code. Patch by Brad Smith.

* bpo-30085: The operator functions without double underscores are
  preferred for clarity. The one with underscores are only kept for
  back-compatibility.


Tests
-----

* bpo-31380: Skip test_httpservers test_undecodable_file on macOS:
  fails on APFS.

* bpo-31705: Skip test_socket.test_sha256() on Linux kernel older than
  4.5. The test fails with ENOKEY on kernel 3.10 (on ppc64le). A fix
  was merged into the kernel 4.5.

* bpo-31174: Fix test_tools.test_unparse: DirectoryTestCase now stores
  the names sample to always test the same files. It prevents false
  alarms when hunting reference leaks.

* bpo-30695: Add the "set_nomemory(start, stop)" and
  "remove_mem_hooks()" functions to the _testcapi module.


Build
-----

* bpo-32059: "detect_modules()" in "setup.py" now also searches the
  sysroot paths when cross-compiling.

* bpo-31957: Fixes Windows SDK version detection when building for
  Windows.

* bpo-31609: Fixes quotes in PCbuild/clean.bat

* bpo-31934: Abort the build when building out of a not clean source
  tree.

* bpo-31926: Fixed Argument Clinic sometimes causing compilation
  errors when there was more than one function and/or method in a .c
  file with the same name.

* bpo-28791: Update Windows builds to use SQLite 3.21.0.

* bpo-28791: Update OS X installer to use SQLite 3.21.0.

* bpo-22140: Prevent double substitution of prefix in python-
  config.sh.

* bpo-31536: Avoid wholesale rebuild after "make regen-all" if nothing
  changed.


Windows
-------

* bpo-1102: Return "None" when "View.Fetch()" returns
  "ERROR_NO_MORE_ITEMS" instead of raising "MSIError". Initial patch
  by Anthony Tuininga.

* bpo-31944: Fixes Modify button in Apps and Features dialog.


macOS
-----

* bpo-31392: Update macOS installer to use OpenSSL 1.0.2m


IDLE
----

* bpo-32207: Improve tk event exception tracebacks in IDLE. When tk
  event handling is driven by IDLE’s run loop, a confusing and
  distracting queue.EMPTY traceback context is no longer added to tk
  event exception tracebacks.  The traceback is now the same as when
  event handling is driven by user code.  Patch based on a suggestion
  by Serhiy Storchaka.

* bpo-32164: Delete unused file idlelib/tabbedpages.py. Use of
  TabbedPageSet in configdialog was replaced by ttk.Notebook.

* bpo-32100: IDLE: Fix old and new bugs in pathbrowser; improve tests.
  Patch mostly by Cheryl Sabella.

* bpo-31858: IDLE – Restrict shell prompt manipulation to the shell.
  Editor and output windows only see an empty last prompt line.  This
  simplifies the code and fixes a minor bug when newline is inserted.
  Sys.ps1, if present, is read on Shell start-up, but is not set or
  changed.

* bpo-31860: The font sample in the IDLE configuration dialog is now
  editable. Changes persist while IDLE remains open

* bpo-31836: Test_code_module now passes if run after test_idle, which
  sets ps1. The code module uses sys.ps1 if present or sets it to ‘>>>
  ‘ if not. Test_code_module now properly tests both behaviors.  Ditto
  for ps2.

* bpo-28603: Fix a TypeError that caused a shell restart when printing
  a traceback that includes an exception that is unhashable. Patch by
  Zane Bitter.

* bpo-13802: Use non-Latin characters in the IDLE’s Font settings
  sample. Even if one selects a font that defines a limited subset of
  the unicode Basic Multilingual Plane, tcl/tk will use other fonts
  that define a character. The expanded example give users of non-
  Latin characters a better idea of what they might see in IDLE’s
  shell and editors. To make room for the expanded sample, frames on
  the Font tab are re-arranged. The Font/Tabs help explains a bit
  about the additions.

* bpo-31460: Simplify the API of IDLE’s Module Browser. Passing a
  widget instead of an flist with a root widget opens the option of
  creating a browser frame that is only part of a window.  Passing a
  full file name instead of pieces assumed to come from a .py file
  opens the possibility of browsing python files that do not end in
  .py.

* bpo-31649: IDLE - Make _htest, _utest parameters keyword only.

* bpo-31559: Remove test order dependence in idle_test.test_browser.

* bpo-31459: Rename IDLE’s module browser from Class Browser to Module
  Browser. The original module-level class and method browser became a
  module browser, with the addition of module-level functions, years
  ago. Nested classes and functions were added yesterday.  For back-
  compatibility, the virtual event <<open-class-browser>>, which
  appears on the Keys tab of the Settings dialog, is not changed.
  Patch by Cheryl Sabella.

* bpo-31500: Default fonts now are scaled on HiDPI displays.

* bpo-1612262: IDLE module browser now shows nested classes and
  functions. Original patches for code and tests by Guilherme Polo and
  Cheryl Sabella, respectively.


Tools/Demos
-----------

* bpo-30722: Make redemo work with Python 3.6 and newer versions.
  Also, remove the "LOCALE" option since it doesn’t work with string
  patterns in Python 3. Patch by Christoph Sarnowski.


C API
-----

* bpo-20891: Fix PyGILState_Ensure(). When PyGILState_Ensure() is
  called in a non-Python thread before PyEval_InitThreads(), only call
  PyEval_InitThreads() after calling PyThreadState_New() to fix a
  crash.

* bpo-31532: Fix memory corruption due to allocator mix in getpath.c
  between Py_GetPath() and Py_SetPath()

* bpo-30697: The "PyExc_RecursionErrorInst" singleton is removed and
  "PyErr_NormalizeException()" does not use it anymore. This singleton
  is persistent and its members being never cleared may cause a
  segfault during finalization of the interpreter. See also bpo-22898.


Python 3.6.3 final
==================

*Release date: 2017-10-03*


Library
-------

* bpo-31641: Re-allow arbitrary iterables in
  "concurrent.futures.as_completed()". Fixes regression in 3.6.3rc1.


Build
-----

* bpo-31662: Fix typos in Windows "uploadrelease.bat" script. Fix
  Windows Doc build issues in "Doc/make.bat".

* bpo-31423: Fix building the PDF documentation with newer versions of
  Sphinx.


Python 3.6.3 release candidate 1
================================

*Release date: 2017-09-18*


Security
--------

* bpo-29781: SSLObject.version() now correctly returns None when
  handshake over BIO has not been performed yet.

* bpo-30947: Upgrade libexpat embedded copy from version 2.2.1 to
  2.2.3 to get security fixes.


Core and Builtins
-----------------

* bpo-31471: Fix an assertion failure in "subprocess.Popen()" on
  Windows, in case the env argument has a bad keys() method. Patch by
  Oren Milman.

* bpo-31418: Fix an assertion failure in "PyErr_WriteUnraisable()" in
  case of an exception with a bad "__module__" attribute. Patch by
  Oren Milman.

* bpo-31416: Fix assertion failures in case of a bad warnings.filters
  or warnings.defaultaction. Patch by Oren Milman.

* bpo-31411: Raise a TypeError instead of SystemError in case
  warnings.onceregistry is not a dictionary. Patch by Oren Milman.

* bpo-31373: Fix several possible instances of undefined behavior due
  to floating-point demotions.

* bpo-30465: Location information ("lineno" and "col_offset") in
  f-strings is now (mostly) correct.  This fixes tools like flake8
  from showing warnings on the wrong line (typically the first line of
  the file).

* bpo-31343: Include sys/sysmacros.h for major(), minor(), and
  makedev(). GNU C libray plans to remove the functions from
  sys/types.h.

* bpo-31291: Fix an assertion failure in
  "zipimport.zipimporter.get_data" on Windows, when the return value
  of "pathname.replace('/','\\')" isn’t a string. Patch by Oren
  Milman.

* bpo-31271: Fix an assertion failure in the write() method of
  "io.TextIOWrapper", when the encoder doesn’t return a bytes object.
  Patch by Oren Milman.

* bpo-31243: Fix a crash in some methods of "io.TextIOWrapper", when
  the decoder’s state is invalid. Patch by Oren Milman.

* bpo-30721: "print" now shows correct usage hint for using Python 2
  redirection syntax.  Patch by Sanyam Khurana.

* bpo-31070: Fix a race condition in importlib _get_module_lock().

* bpo-31095: Fix potential crash during GC caused by "tp_dealloc"
  which doesn’t call "PyObject_GC_UnTrack()".

* bpo-31071: Avoid masking original TypeError in call with * unpacking
  when other arguments are passed.

* bpo-30978: str.format_map() now passes key lookup exceptions
  through. Previously any exception was replaced with a KeyError
  exception.

* bpo-30808: Use _Py_atomic API for concurrency-sensitive signal
  state.

* bpo-30876: Relative import from unloaded package now reimports the
  package instead of failing with SystemError.  Relative import from
  non-package now fails with ImportError rather than SystemError.

* bpo-30703: Improve signal delivery. Avoid using Py_AddPendingCall
  from signal handler, to avoid calling signal-unsafe functions. The
  tests I’m adding here fail without the rest of the patch, on Linux
  and OS X. This means our signal delivery logic had defects (some
  signals could be lost).

* bpo-30765: Avoid blocking in pthread_mutex_lock() when
  PyThread_acquire_lock() is asked not to block.

* bpo-31161: Make sure the ‘Missing parentheses’ syntax error message
  is only applied to SyntaxError, not to subclasses. Patch by Martijn
  Pieters.

* bpo-30814: Fixed a race condition when import a submodule from a
  package.

* bpo-30597: "print" now shows expected input in custom error message
  when used as a Python 2 statement. Patch by Sanyam Khurana.


Library
-------

* bpo-31499: xml.etree: Fix a crash when a parser is part of a
  reference cycle.

* bpo-28556: typing.get_type_hints now finds the right globalns for
  classes and modules by default (when no "globalns" was specified by
  the caller).

* bpo-28556: Speed improvements to the "typing" module.  Original PRs
  by Ivan Levkivskyi and Mitar.

* bpo-31544: The C accelerator module of ElementTree ignored
  exceptions raised when looking up TreeBuilder target methods in
  XMLParser().

* bpo-31234: socket.create_connection() now fixes manually a reference
  cycle: clear the variable storing the last exception on success.

* bpo-31457: LoggerAdapter objects can now be nested.

* bpo-31400: Improves SSL error handling to avoid losing error
  numbers.

* bpo-28958: ssl.SSLContext() now uses OpenSSL error information when
  a context cannot be instantiated.

* bpo-27340: SSLSocket.sendall() now uses memoryview to create slices
  of data. This fixes support for all bytes-like object. It is also
  more efficient and avoids costly copies.

* bpo-31178: Fix string concatenation bug in rare error path in the
  subprocess module

* bpo-31350: Micro-optimize "asyncio._get_running_loop()" to become up
  to 10% faster.

* bpo-31170: expat: Update libexpat from 2.2.3 to 2.2.4. Fix copying
  of partial characters for UTF-8 input (libexpat bug 115):
  https://github.com/libexpat/libexpat/issues/115

* bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3.

* bpo-29212: Fix concurrent.futures.thread.ThreadPoolExecutor threads
  to have a non repr() based thread name by default when no
  thread_name_prefix is supplied. They will now identify themselves as
  “ThreadPoolExecutor-y_n”.

* bpo-9146: Fix a segmentation fault in _hashopenssl when standard
  hash functions such as md5 are not available in the linked OpenSSL
  library.  As in some special FIPS-140 build environments.

* bpo-27144: The "map()" and "as_completed()" iterators in
  "concurrent.futures" now avoid keeping a reference to yielded
  objects.

* bpo-10746: Fix ctypes producing wrong **PEP 3118** type codes for
  integer types.

* bpo-22536: The subprocess module now sets the filename when
  FileNotFoundError is raised on POSIX systems due to the executable
  or cwd not being found.

* bpo-31249: concurrent.futures: WorkItem.run() used by
  ThreadPoolExecutor now breaks a reference cycle between an exception
  object and the WorkItem object.

* bpo-31247: xmlrpc.server now explicitly breaks reference cycles when
  using sys.exc_info() in code handling exceptions.

* bpo-30102: The ssl and hashlib modules now call
  OPENSSL_add_all_algorithms_noconf() on OpenSSL < 1.1.0. The function
  detects CPU features and enables optimizations on some CPU
  architectures such as POWER8. Patch is based on research from
  Gustavo Serra Scalet.

* bpo-31185: Fixed miscellaneous errors in asyncio speedup module.

* bpo-31135: ttk: fix the destroy() method of LabeledScale and
  OptionMenu classes. Call the parent destroy() method even if the
  used attribute doesn’t exist. The LabeledScale.destroy() method now
  also explicitly clears label and scale attributes to help the
  garbage collector to destroy all widgets.

* bpo-31107: Fix "copyreg._slotnames()" mangled attribute calculation
  for classes whose name begins with an underscore. Patch by Shane
  Harvey.

* bpo-31061: Fixed a crash when using asyncio and threads.

* bpo-30502: Fix handling of long oids in ssl.  Based on patch by
  Christian Heimes.

* bpo-30119: ftplib.FTP.putline() now throws ValueError on commands
  that contains CR or LF. Patch by Dong-hee Na.

* bpo-30595: multiprocessing.Queue.get() with a timeout now polls its
  reader in non-blocking mode if it succeeded to acquire the lock but
  the acquire took longer than the timeout.

* bpo-29403: Fix "unittest.mock"’s autospec to not fail on method-
  bound builtin functions.  Patch by Aaron Gallagher.

* bpo-30961: Fix decrementing a borrowed reference in tracemalloc.

* bpo-25684: Change "ttk.OptionMenu" radiobuttons to be unique across
  instances of "OptionMenu".

* bpo-30886: Fix multiprocessing.Queue.join_thread(): it now waits
  until the thread completes, even if the thread was started by the
  same process which created the queue.

* bpo-29854: Fix segfault in readline when using readline’s history-
  size option.  Patch by Nir Soffer.

* bpo-30319: socket.close() now ignores ECONNRESET error.

* bpo-30828: Fix out of bounds write in
  "asyncio.CFuture.remove_done_callback()".

* bpo-30807: signal.setitimer() may disable the timer when passed a
  tiny value. Tiny values (such as 1e-6) are valid non-zero values for
  setitimer(), which is specified as taking microsecond-resolution
  intervals. However, on some platform, our conversion routine could
  convert 1e-6 into a zero interval, therefore disabling the timer
  instead of (re-)scheduling it.

* bpo-30441: Fix bug when modifying os.environ while iterating over it

* bpo-30532: Fix email header value parser dropping folding white
  space in certain cases.

* bpo-30879: os.listdir() and os.scandir() now emit bytes names when
  called with bytes-like argument.

* bpo-30746: Prohibited the ‘=’ character in environment variable
  names in "os.putenv()" and "os.spawn*()".

* bpo-29755: Fixed the lgettext() family of functions in the gettext
  module. They now always return bytes.


Documentation
-------------

* bpo-31294: Fix incomplete code snippet in the ZeroMQSocketListener
  and ZeroMQSocketHandler examples and adapt them to Python 3.

* bpo-21649: Add RFC 7525 and Mozilla server side TLS links to SSL
  documentation.

* bpo-30803: Clarify doc on truth value testing. Original patch by
  Peter Thomassen.


Tests
-----

* bpo-31320: Silence traceback in test_ssl

* bpo-25674: Remove sha256.tbs-internet.com ssl test

* bpo-30715: Address ALPN callback changes for OpenSSL 1.1.0f. The
  latest version behaves like OpenSSL 1.0.2 and no longer aborts
  handshake.

* bpo-30822: regrtest: Exclude tzdata from regrtest –all. When running
  the test suite using –use=all / -u all, exclude tzdata since it
  makes test_datetime too slow (15-20 min on some buildbots) which
  then times out on some buildbots. Fix also regrtest command line
  parser to allow passing -u extralargefile to run test_zipfile64.


Build
-----

* bpo-30854: Fix compile error when compiling –without-threads. Patch
  by Masayuki Yamamoto.


Windows
-------

* bpo-30389: Adds detection of Visual Studio 2017 to distutils on
  Windows.

* bpo-31340: Change to building with MSVC v141 (included with Visual
  Studio 2017)

* bpo-30581: os.cpu_count() now returns the correct number of
  processors on Windows when the number of logical processors is
  greater than 64.

* bpo-30731: Add a missing xmlns to python.manifest so that it matches
  the schema.


IDLE
----

* bpo-31493: IDLE code context – fix code update and font update
  timers. Canceling timers prevents a warning message when test_idle
  completes.

* bpo-31488: IDLE - Update non-key options in former extension
  classes. When applying configdialog changes, call .reload for each
  feature class. Change ParenMatch so updated options affect existing
  instances attached to existing editor windows.

* bpo-31477: IDLE - Improve rstrip entry in doc. Strip trailing
  whitespace strips more than blank spaces.  Multiline string literals
  are not skipped.

* bpo-31480: IDLE - make tests pass with zzdummy extension disabled by
  default.

* bpo-31421: Document how IDLE runs tkinter programs. IDLE calls
  tcl/tk update in the background in order to make live interaction
  and experimentation with tkinter applications much easier.

* bpo-31414: IDLE – fix tk entry box tests by deleting first. Adding
  to an int entry is not the same as deleting and inserting because
  int(‘’) will fail.

* bpo-31051: Rearrange IDLE configdialog GenPage into Window, Editor,
  and Help sections.

* bpo-30617: IDLE - Add docstrings and tests for outwin subclass of
  editor. Move some data and functions from the class to module level.
  Patch by Cheryl Sabella.

* bpo-31287: IDLE - Do not modify tkinter.message in
  test_configdialog.

* bpo-27099: Convert IDLE’s built-in ‘extensions’ to regular features.
  About 10 IDLE features were implemented as supposedly optional
  extensions. Their different behavior could be confusing or worse for
  users and not good for maintenance. Hence the conversion. The main
  difference for users is that user configurable key bindings for
  builtin features are now handled uniformly. Now, editing a binding
  in a keyset only affects its value in the keyset. All bindings are
  defined together in the system-specific default keysets in config-
  extensions.def. All custom keysets are saved as a whole in config-
  extension.cfg.  All take effect as soon as one clicks Apply or Ok.
  The affected events are ‘<<force-open-completions>>’, ‘<<expand-
  word>>’, ‘<<force-open-calltip>>’, ‘<<flash-paren>>’, ‘<<format-
  paragraph>>’, ‘<<run-module>>’, ‘<<check-module>>’, and ‘<<zoom-
  height>>’.  Any (global) customizations made before 3.6.3 will not
  affect their keyset-specific customization after 3.6.3. and vice
  versa. Initial patch by Charles Wohlganger.

* bpo-31206: IDLE: Factor HighPage(Frame) class from ConfigDialog.
  Patch by Cheryl Sabella.

* bpo-31001: Add tests for configdialog highlight tab.  Patch by
  Cheryl Sabella.

* bpo-31205: IDLE: Factor KeysPage(Frame) class from ConfigDialog.
  The slightly modified tests continue to pass.  Patch by Cheryl
  Sabella.

* bpo-31130: IDLE – stop leaks in test_configdialog. Initial patch by
  Victor Stinner.

* bpo-31002: Add tests for configdialog keys tab. Patch by Cheryl
  Sabella.

* bpo-19903: IDLE: Calltips use "inspect.signature" instead of
  "inspect.getfullargspec". This improves calltips for builtins
  converted to use Argument Clinic. Patch by Louie Lu.

* bpo-31083: IDLE - Add an outline of a TabPage class in configdialog.
  Update existing classes to match outline. Initial patch by Cheryl
  Sabella.

* bpo-31050: Factor GenPage(Frame) class from ConfigDialog. The
  slightly modified tests continue to pass. Patch by Cheryl Sabella.

* bpo-31004: IDLE - Factor FontPage(Frame) class from ConfigDialog.
  Slightly modified tests continue to pass. Fix General tests. Patch
  mostly by Cheryl Sabella.

* bpo-30781: IDLE - Use ttk widgets in ConfigDialog. Patches by Terry
  Jan Reedy and Cheryl Sabella.

* bpo-31060: IDLE - Finish rearranging methods of ConfigDialog
  Grouping methods pertaining to each tab and the buttons will aid
  writing tests and improving the tabs and will enable splitting the
  groups into classes.

* bpo-30853: IDLE – Factor a VarTrace class out of ConfigDialog.
  Instance tracers manages pairs consisting of a tk variable and a
  callback function. When tracing is turned on, setting the variable
  calls the function.  Test coverage for the new class is 100%.

* bpo-31003: IDLE: Add more tests for General tab.

* bpo-30993: IDLE - Improve configdialog font page and tests. In
  configdialog: Document causal pathways in create_font_tab docstring.
  Simplify some attribute names. Move set_samples calls to
  var_changed_font (idea from Cheryl Sabella).  Move related functions
  to positions after the create widgets function. In
  test_configdialog: Fix test_font_set so not order dependent.  Fix
  renamed test_indent_scale so it tests the widget. Adjust tests for
  movement of set_samples call.  Add tests for load functions.  Put
  all font tests in one class and tab indent tests in another.  Except
  for two lines, these tests completely cover the related functions.

* bpo-30981: IDLE – Add more configdialog font page tests.

* bpo-28523: IDLE: replace ‘colour’ with ‘color’ in configdialog.

* bpo-30917: Add tests for idlelib.config.IdleConf. Increase coverage
  from 46% to 96%. Patch by Louie Lu.

* bpo-30934: Document coverage details for idlelib tests. Add section
  to idlelib/idle-test/README.txt. Include check that branches are
  taken both ways. Exclude IDLE-specific code that does not run during
  unit tests.

* bpo-30913: IDLE: Document ConfigDialog tk Vars, methods, and widgets
  in docstrings This will facilitate improving the dialog and
  splitting up the class. Original patch by Cheryl Sabella.

* bpo-30899: IDLE: Add tests for ConfigParser subclasses in config.
  Patch by Louie Lu.

* bpo-30881: IDLE: Add docstrings to browser.py. Patch by Cheryl
  Sabella.

* bpo-30851: IDLE: Remove unused variables in configdialog.  One is a
  duplicate, one is set but cannot be altered by users. Patch by
  Cheryl Sabella.

* bpo-30870: IDLE: In Settings dialog, select font with Up, Down keys
  as well as mouse. Initial patch by Louie Lu.

* bpo-8231: IDLE: call config.IdleConf.GetUserCfgDir only once.

* bpo-30779: IDLE: Factor ConfigChanges class from configdialog, put
  in config; test. * In config, put dump test code in a function; run
  it and unittest in   ‘if __name__ == ‘__main__’. * Add class
  config.ConfigChanges based on changes_class_v4.py on bpo issue. *
  Add class test_config.ChangesTest, partly using
  configdialog_tests_v1.py. * Revise configdialog to use
  ConfigChanges; see tracker msg297804. * Revise test_configdialog to
  match configdialog changes. * Remove configdialog functions unused
  or moved to ConfigChanges. Cheryl Sabella contributed parts of the
  patch.

* bpo-30777: IDLE: configdialog - Add docstrings and fix comments.
  Patch by Cheryl Sabella.

* bpo-30495: IDLE: Improve textview with docstrings, PEP8 names, and
  more tests. Patch by Cheryl Sabella.

* bpo-30723: IDLE: Make several improvements to parenmatch. Add
  ‘parens’ style to highlight both opener and closer. Make ‘default’
  style, which is not default, a synonym for ‘opener’. Make time-delay
  work the same with all styles. Add help for config dialog extensions
  tab, including help for parenmatch. Add new tests.  Original patch
  by Charles Wohlganger.

* bpo-30674: IDLE: add docstrings to grep module. Patch by Cheryl
  Sabella

* bpo-21519: IDLE’s basic custom key entry dialog now detects
  duplicates properly. Original patch by Saimadhav Heblikar.

* bpo-29910: IDLE no longer deletes a character after commenting out a
  region by a key shortcut.  Add "return 'break'" for this and other
  potential conflicts between IDLE and default key bindings.

* bpo-30728: Review and change idlelib.configdialog names. Lowercase
  method and attribute names. Replace ‘colour’ with ‘color’, expand
  overly cryptic names, delete unneeded underscores. Replace "import
  *" with specific imports. Patches by Cheryl Sabella.

* bpo-6739: IDLE: Verify user-entered key sequences by trying to bind
  them with tk. Add tests for all 3 validation functions. Original
  patch by G Polo.  Tests added by Cheryl Sabella.


Tools/Demos
-----------

* bpo-30983: gdb integration commands (py-bt, etc.) work on optimized
  shared builds now, too.  **PEP 523** introduced
  _PyEval_EvalFrameDefault which inlines PyEval_EvalFrameEx on non-
  debug shared builds.  This broke the ability to use py-bt, py-up,
  and a few other Python-specific gdb integrations. The problem is
  fixed by only looking for _PyEval_EvalFrameDefault frames in python-
  gdb.py.  Original patch by Bruno “Polaco” Penteado.


Python 3.6.2 final
==================

*Release date: 2017-07-17*

No changes since release candidate 2


Python 3.6.2 release candidate 2
================================

*Release date: 2017-07-07*


Security
--------

* bpo-30730: Prevent environment variables injection in subprocess on
  Windows.  Prevent passing other environment variables and command
  arguments.

* bpo-30694: Upgrade expat copy from 2.2.0 to 2.2.1 to get fixes of
  multiple security vulnerabilities including: CVE-2017-9233 (External
  entity infinite loop DoS), CVE-2016-9063 (Integer overflow, re-fix),
  CVE-2016-0718 (Fix regression bugs from 2.2.0’s fix to
  CVE-2016-0718) and CVE-2012-0876 (Counter hash flooding with
  SipHash). Note: the CVE-2016-5300 (Use os-specific entropy sources
  like getrandom) doesn’t impact Python, since Python already gets
  entropy from the OS to set the expat secret using
  "XML_SetHashSalt()".

* bpo-30500: Fix urllib.parse.splithost() to correctly parse
  fragments. For example, "splithost('//127.0.0.1#@evil.com/')" now
  correctly returns the "127.0.0.1" host, instead of treating
  "@evil.com" as the host in an authentication ("login@host").


Python 3.6.2 release candidate 1
================================

*Release date: 2017-06-17*


Security
--------

* bpo-29591: Update expat copy from 2.1.1 to 2.2.0 to get fixes of
  CVE-2016-0718 and CVE-2016-4472. See
  https://sourceforge.net/p/expat/bugs/537/ for more information.


Core and Builtins
-----------------

* bpo-30682: Removed a too-strict assertion that failed for certain
  f-strings, such as eval(“f’\n’”) and eval(“f’\r’”).

* bpo-30604: Move co_extra_freefuncs to not be per-thread to avoid
  crashes

* bpo-29104: Fixed parsing backslashes in f-strings.

* bpo-27945: Fixed various segfaults with dict when input collections
  are mutated during searching, inserting or comparing.  Based on
  patches by Duane Griffin and Tim Mitchell.

* bpo-25794: Fixed type.__setattr__() and type.__delattr__() for non-
  interned attribute names.  Based on patch by Eryk Sun.

* bpo-30039: If a KeyboardInterrupt happens when the interpreter is in
  the middle of resuming a chain of nested ‘yield from’ or ‘await’
  calls, it’s now correctly delivered to the innermost frame.

* bpo-12414: sys.getsizeof() on a code object now returns the sizes
  which includes the code struct and sizes of objects which it
  references. Patch by Dong-hee Na.

* bpo-29949: Fix memory usage regression of set and frozenset object.

* bpo-29935: Fixed error messages in the index() method of tuple, list
  and deque when pass indices of wrong type.

* bpo-29859: Show correct error messages when any of the pthread_*
  calls in thread_pthread.h fails.

* bpo-28876: "bool(range)" works even if "len(range)" raises
  "OverflowError".

* bpo-29600: Fix wrapping coroutine return values in StopIteration.

* bpo-28856: Fix an oversight that %b format for bytes should support
  objects follow the buffer protocol.

* bpo-29714: Fix a regression that bytes format may fail when
  containing zero bytes inside.

* bpo-29478: If max_line_length=None is specified while using the
  Compat32 policy, it is no longer ignored.  Patch by Mircea Cosbuc.


Library
-------

* bpo-30616: Functional API of enum allows to create empty enums.
  Patched by Dong-hee Na

* bpo-30038: Fix race condition between signal delivery and wakeup
  file descriptor. Patch by Nathaniel Smith.

* bpo-23894: lib2to3 now recognizes "rb'...'" and "f'...'" strings.

* bpo-23890: unittest.TestCase.assertRaises() now manually breaks a
  reference cycle to not keep objects alive longer than expected.

* bpo-30149: inspect.signature() now supports callables with variable-
  argument parameters wrapped with partialmethod. Patch by Dong-hee
  Na.

* bpo-30645: Fix path calculation in imp.load_package(), fixing it for
  cases when a package is only shipped with bytecodes. Patch by
  Alexandru Ardelean.

* bpo-29931: Fixed comparison check for ipaddress.ip_interface
  objects. Patch by Sanjay Sundaresan.

* bpo-30605: re.compile() no longer raises a BytesWarning when
  compiling a bytes instance with misplaced inline modifier.  Patch by
  Roy Williams.

* bpo-24484: Avoid race condition in multiprocessing cleanup (#2159)

* bpo-28994: The traceback no longer displayed for SystemExit raised
  in a callback registered by atexit.

* bpo-30508: Don’t log exceptions if Task/Future “cancel()” method was
  called.

* bpo-28556: Updates to typing module: Add generic
  AsyncContextManager, add support for ContextManager on all versions.
  Original PRs by Jelle Zijlstra and Ivan Levkivskyi

* bpo-29870: Fix ssl sockets leaks when connection is aborted in
  asyncio/ssl implementation. Patch by Michaël Sghaïer.

* bpo-29743: Closing transport during handshake process leaks open
  socket. Patch by Nikolay Kim

* bpo-27585: Fix waiter cancellation in asyncio.Lock. Patch by Mathieu
  Sornay.

* bpo-30418: On Windows, subprocess.Popen.communicate() now also
  ignore EINVAL on stdin.write() if the child process is still running
  but closed the pipe.

* bpo-29822: inspect.isabstract() now works during __init_subclass__.
  Patch by Nate Soares.

* bpo-29581: ABCMeta.__new__ now accepts "**kwargs", allowing abstract
  base classes to use keyword parameters in __init_subclass__. Patch
  by Nate Soares.

* bpo-30557: faulthandler now correctly filters and displays exception
  codes on Windows

* bpo-30378: Fix the problem that logging.handlers.SysLogHandler
  cannot handle IPv6 addresses.

* bpo-29960: Preserve generator state when _random.Random.setstate()
  raises an exception. Patch by Bryan Olson.

* bpo-30414: multiprocessing.Queue._feed background running thread do
  not break from main loop on exception.

* bpo-30003: Fix handling escape characters in HZ codec.  Based on
  patch by Ma Lin.

* bpo-30301: Fix AttributeError when using SimpleQueue.empty() under
  *spawn* and *forkserver* start methods.

* bpo-30329: imaplib and poplib now catch the Windows socket WSAEINVAL
  error (code 10022) on shutdown(SHUT_RDWR): An invalid operation was
  attempted. This error occurs sometimes on SSL connections.

* bpo-30375: Warnings emitted when compile a regular expression now
  always point to the line in the user code.  Previously they could
  point into inners of the re module if emitted from inside of groups
  or conditionals.

* bpo-30048: Fixed "Task.cancel()" can be ignored when the task is
  running coroutine and the coroutine returned without any more
  "await".

* bpo-30266: contextlib.AbstractContextManager now supports anti-
  registration by setting __enter__ = None or __exit__ = None,
  following the pattern introduced in bpo-25958. Patch by Jelle
  Zijlstra.

* bpo-30298: Weaken the condition of deprecation warnings for inline
  modifiers. Now allowed several subsequential inline modifiers at the
  start of the pattern (e.g. "'(?i)(?s)...'").  In verbose mode
  whitespaces and comments now are allowed before and between inline
  modifiers (e.g. "'(?x) (?i) (?s)...'").

* bpo-29990: Fix range checking in GB18030 decoder.  Original patch by
  Ma Lin.

* bpo-26293: Change resulted because of zipfile breakage. (See also:
  bpo-29094)

* bpo-30243: Removed the __init__ methods of _json’s scanner and
  encoder. Misusing them could cause memory leaks or crashes.  Now
  scanner and encoder objects are completely initialized in the
  __new__ methods.

* bpo-30185: Avoid KeyboardInterrupt tracebacks in forkserver helper
  process when Ctrl-C is received.

* bpo-28556: Various updates to typing module: add typing.NoReturn
  type, use WrapperDescriptorType, minor bug-fixes.  Original PRs by
  Jim Fasarakis-Hilliard and Ivan Levkivskyi.

* bpo-30205: Fix getsockname() for unbound AF_UNIX sockets on Linux.

* bpo-30070: Fixed leaks and crashes in errors handling in the parser
  module.

* bpo-30061: Fixed crashes in IOBase methods __next__() and
  readlines() when readline() or __next__() respectively return non-
  sizeable object. Fixed possible other errors caused by not checking
  results of PyObject_Size(), PySequence_Size(), or PyMapping_Size().

* bpo-30017: Allowed calling the close() method of the zip entry
  writer object multiple times.  Writing to a closed writer now always
  produces a ValueError.

* bpo-30068: _io._IOBase.readlines will check if it’s closed first
  when hint is present.

* bpo-29694: Fixed race condition in pathlib mkdir with flags
  parents=True. Patch by Armin Rigo.

* bpo-29692: Fixed arbitrary unchaining of RuntimeError exceptions in
  contextlib.contextmanager.  Patch by Siddharth Velankar.

* bpo-29998: Pickling and copying ImportError now preserves name and
  path attributes.

* bpo-29953: Fixed memory leaks in the replace() method of datetime
  and time objects when pass out of bound fold argument.

* bpo-29942: Fix a crash in itertools.chain.from_iterable when
  encountering long runs of empty iterables.

* bpo-27863: Fixed multiple crashes in ElementTree caused by race
  conditions and wrong types.

* bpo-28699: Fixed a bug in pools in multiprocessing.pool that raising
  an exception at the very first of an iterable may swallow the
  exception or make the program hang. Patch by Davin Potts and Xiang
  Zhang.

* bpo-25803: Avoid incorrect errors raised by
  Path.mkdir(exist_ok=True) when the OS gives priority to errors such
  as EACCES over EEXIST.

* bpo-29861: Release references to tasks, their arguments and their
  results as soon as they are finished in multiprocessing.Pool.

* bpo-29884: faulthandler: Restore the old sigaltstack during
  teardown. Patch by Christophe Zeitouny.

* bpo-25455: Fixed crashes in repr of recursive buffered file-like
  objects.

* bpo-29800: Fix crashes in partial.__repr__ if the keys of
  partial.keywords are not strings.  Patch by Michael Seifert.

* bpo-29742: get_extra_info() raises exception if get called on closed
  ssl transport. Patch by Nikolay Kim.

* bpo-8256: Fixed possible failing or crashing input() if attributes
  “encoding” or “errors” of sys.stdin or sys.stdout are not set or are
  not strings.

* bpo-28298: Fix a bug that prevented array ‘Q’, ‘L’ and ‘I’ from
  accepting big intables (objects that have __int__) as elements.
  Patch by Oren Milman.

* bpo-28231: The zipfile module now accepts path-like objects for
  external paths.

* bpo-26915: index() and count() methods of collections.abc.Sequence
  now check identity before checking equality when do comparisons.

* bpo-29615: SimpleXMLRPCDispatcher no longer chains KeyError (or any
  other exception) to exception(s) raised in the dispatched methods.
  Patch by Petr Motejlek.

* bpo-30177: path.resolve(strict=False) no longer cuts the path after
  the first element not present in the filesystem.  Patch by Antoine
  Pietri.


IDLE
----

* bpo-15786: Fix several problems with IDLE’s autocompletion box. The
  following should now work: clicking on selection box items; using
  the scrollbar; selecting an item by hitting Return. Hangs on MacOSX
  should no longer happen. Patch by Louie Lu.

* bpo-25514: Add doc subsubsection about IDLE failure to start. Popup
  no-connection message directs users to this section.

* bpo-30642: Fix reference leaks in IDLE tests. Patches by Louie Lu
  and Terry Jan Reedy.

* bpo-30495: Add docstrings for textview.py and use PEP8 names.
  Patches by Cheryl Sabella and Terry Jan Reedy.

* bpo-30290: Help-about: use pep8 names and add tests. Increase
  coverage to 100%. Patches by Louie Lu, Cheryl Sabella, and Terry Jan
  Reedy.

* bpo-30303: Add _utest option to textview; add new tests. Increase
  coverage to 100%. Patches by Louie Lu and Terry Jan Reedy.


C API
-----

* bpo-27867: Function PySlice_GetIndicesEx() no longer replaced with a
  macro if Py_LIMITED_API is not set.


Build
-----

* bpo-29941: Add "--with-assertions" configure flag to explicitly
  enable C "assert()" checks. Defaults to off. "--with-pydebug"
  implies "--with-assertions".

* bpo-28787: Fix out-of-tree builds of Python when configured with "--
  with--dtrace".

* bpo-29243: Prevent unnecessary rebuilding of Python during "make
  test", "make install" and some other make targets when configured
  with "--enable-optimizations".

* bpo-23404: Don’t regenerate generated files based on file
  modification time anymore: the action is now explicit. Replace "make
  touch" with "make regen-all".

* bpo-29643: Fix "--enable-optimization" didn’t work.


Documentation
-------------

* bpo-30176: Add missing attribute related constants in curses
  documentation.

* bpo-30052: the link targets for "bytes()" and "bytearray()" are now
  their respective type definitions, rather than the corresponding
  builtin function entries. Use bytes and bytearray to reference the
  latter. In order to ensure this and future cross-reference updates
  are applied automatically, the daily documentation builds now
  disable the default output caching features in Sphinx.

* bpo-26985: Add missing info of code object in inspect documentation.


Tools/Demos
-----------

* bpo-29367: python-gdb.py now supports also "method-wrapper"
  ("wrapperobject") objects.


Tests
-----

* bpo-30357: test_thread: setUp() now uses support.threading_setup()
  and support.threading_cleanup() to wait until threads complete to
  avoid random side effects on following tests. Initial patch written
  by Grzegorz Grzywacz.

* bpo-30197: Enhanced functions swap_attr() and swap_item() in the
  test.support module. They now work when delete replaced attribute or
  item inside the with statement.  The old value of the attribute or
  item (or None if it doesn’t exist) now will be assigned to the
  target of the “as” clause, if there is one.


Windows
-------

* bpo-30687: Locate msbuild.exe on Windows when building rather than
  vcvarsall.bat

* bpo-30450: The build process on Windows no longer depends on
  Subversion, instead pulling external code from GitHub via a Python
  script.  If Python 3.6 is not found on the system (via "py -3.6"),
  NuGet is used to download a copy of 32-bit Python.


Python 3.6.1 final
==================

*Release date: 2017-03-21*


Core and Builtins
-----------------

* bpo-29723: The "sys.path[0]" initialization change for bpo-29139
  caused a regression by revealing an inconsistency in how sys.path is
  initialized when executing "__main__" from a zipfile, directory, or
  other import location. The interpreter now consistently avoids ever
  adding the import location’s parent directory to "sys.path", and
  ensures no other "sys.path" entries are inadvertently modified when
  inserting the import location named on the command line.


Build
-----

* bpo-27593: fix format of git information used in sys.version

* Fix incompatible comment in python.h


Python 3.6.1 release candidate 1
================================

*Release date: 2017-03-04*


Core and Builtins
-----------------

* bpo-28893: Set correct __cause__ for errors about invalid awaitables
  returned from __aiter__ and __anext__.

* bpo-29683: Fixes to memory allocation in _PyCode_SetExtra.  Patch by
  Brian Coleman.

* bpo-29684: Fix minor regression of PyEval_CallObjectWithKeywords. It
  should raise TypeError when kwargs is not a dict.  But it might
  cause segv when args=NULL and kwargs is not a dict.

* bpo-28598: Support __rmod__ for subclasses of str being called
  before str.__mod__. Patch by Martijn Pieters.

* bpo-29607: Fix stack_effect computation for CALL_FUNCTION_EX. Patch
  by Matthieu Dartiailh.

* bpo-29602: Fix incorrect handling of signed zeros in complex
  constructor for complex subclasses and for inputs having a
  __complex__ method. Patch by Serhiy Storchaka.

* bpo-29347: Fixed possibly dereferencing undefined pointers when
  creating weakref objects.

* bpo-29438: Fixed use-after-free problem in key sharing dict.

* bpo-29319: Prevent RunMainFromImporter overwriting sys.path[0].

* bpo-29337: Fixed possible BytesWarning when compare the code
  objects. Warnings could be emitted at compile time.

* bpo-29327: Fixed a crash when pass the iterable keyword argument to
  sorted().

* bpo-29034: Fix memory leak and use-after-free in os module
  (path_converter).

* bpo-29159: Fix regression in bytes(x) when x.__index__() raises
  Exception.

* bpo-28932: Do not include <sys/random.h> if it does not exist.

* bpo-25677: Correct the positioning of the syntax error caret for
  indented blocks. Based on patch by Michael Layzell.

* bpo-29000: Fixed bytes formatting of octals with zero padding in
  alternate form.

* bpo-26919: On Android, operating system data is now always
  encoded/decoded to/from UTF-8, instead of the locale encoding to
  avoid inconsistencies with os.fsencode() and os.fsdecode() which are
  already using UTF-8.

* bpo-28991: functools.lru_cache() was susceptible to an obscure
  reentrancy bug triggerable by a monkey-patched len() function.

* bpo-28739: f-string expressions are no longer accepted as docstrings
  and by ast.literal_eval() even if they do not include expressions.

* bpo-28512: Fixed setting the offset attribute of SyntaxError by
  PyErr_SyntaxLocationEx() and PyErr_SyntaxLocationObject().

* bpo-28918: Fix the cross compilation of xxlimited when Python has
  been built with Py_DEBUG defined.

* bpo-28731: Optimize _PyDict_NewPresized() to create correct size
  dict. Improve speed of dict literal with constant keys up to 30%.


Library
-------

* bpo-29169: Update zlib to 1.2.11.

* bpo-29623: Allow use of path-like object as a single argument in
  ConfigParser.read(). Patch by David Ellis.

* bpo-28963: Fix out of bound iteration in
  asyncio.Future.remove_done_callback implemented in C.

* bpo-29704: asyncio.subprocess.SubprocessStreamProtocol no longer
  closes before all pipes are closed.

* bpo-29271: Fix Task.current_task and Task.all_tasks implemented in C
  to accept None argument as their pure Python implementation.

* bpo-29703: Fix asyncio to support instantiation of new event loops
  in child processes.

* bpo-29376: Fix assertion error in threading._DummyThread.is_alive().

* bpo-28624: Add a test that checks that cwd parameter of Popen()
  accepts PathLike objects.  Patch by Sayan Chowdhury.

* bpo-28518: Start a transaction implicitly before a DML statement.
  Patch by Aviv Palivoda.

* bpo-29532: Altering a kwarg dictionary passed to functools.partial()
  no longer affects a partial object after creation.

* bpo-29110: Fix file object leak in aifc.open() when file is given as
  a filesystem path and is not in valid AIFF format. Patch by Anthony
  Zhang.

* bpo-28556: Various updates to typing module: typing.Counter,
  typing.ChainMap, improved ABC caching, etc. Original PRs by Jelle
  Zijlstra, Ivan Levkivskyi, Manuel Krebber, and Łukasz Langa.

* bpo-29100: Fix datetime.fromtimestamp() regression introduced in
  Python 3.6.0: check minimum and maximum years.

* bpo-29519: Fix weakref spewing exceptions during interpreter
  shutdown when used with a rare combination of multiprocessing and
  custom codecs.

* bpo-29416: Prevent infinite loop in pathlib.Path.mkdir

* bpo-29444: Fixed out-of-bounds buffer access in the group() method
  of the match object. Based on patch by WGH.

* bpo-29335: Fix subprocess.Popen.wait() when the child process has
  exited to a stopped instead of terminated state (ex: when under
  ptrace).

* bpo-29290: Fix a regression in argparse that help messages would
  wrap at non-breaking spaces.

* bpo-28735: Fixed the comparison of mock.MagickMock with mock.ANY.

* bpo-29316: Restore the provisional status of typing module, add
  corresponding note to documentation. Patch by Ivan L.

* bpo-29219: Fixed infinite recursion in the repr of uninitialized
  ctypes.CDLL instances.

* bpo-29011: Fix an important omission by adding Deque to the typing
  module.

* bpo-28969: Fixed race condition in C implementation of
  functools.lru_cache. KeyError could be raised when cached function
  with full cache was simultaneously called from different threads
  with the same uncached arguments.

* bpo-29142: In urllib.request, suffixes in no_proxy environment
  variable with leading dots could match related hostnames again (e.g.
  .b.c matches a.b.c). Patch by Milan Oberkirch.

* bpo-28961: Fix unittest.mock._Call helper: don’t ignore the name
  parameter anymore. Patch written by Jiajun Huang.

* bpo-29203: functools.lru_cache() now respects **PEP 468** and
  preserves the order of keyword arguments.  f(a=1, b=2) is now cached
  separately from f(b=2, a=1) since both calls could potentially give
  different results.

* bpo-15812: inspect.getframeinfo() now correctly shows the first line
  of a context. Patch by Sam Breese.

* bpo-29094: Offsets in a ZIP file created with extern file object and
  modes “w” and “x” now are relative to the start of the file.

* bpo-29085: Allow random.Random.seed() to use high quality OS
  randomness rather than the pid and time.

* bpo-29061: Fixed bug in secrets.randbelow() which would hang when
  given a negative input.  Patch by Brendan Donegan.

* bpo-29079: Prevent infinite loop in pathlib.resolve() on Windows

* bpo-13051: Fixed recursion errors in large or resized
  curses.textpad.Textbox.  Based on patch by Tycho Andersen.

* bpo-29119: Fix weakrefs in the pure python version of
  collections.OrderedDict move_to_end() method. Contributed by Andra
  Bogildea.

* bpo-9770: curses.ascii predicates now work correctly with negative
  integers.

* bpo-28427: old keys should not remove new values from
  WeakValueDictionary when collecting from another thread.

* bpo-28923: Remove editor artifacts from Tix.py.

* bpo-29055: Neaten-up empty population error on random.choice() by
  suppressing the upstream exception.

* bpo-28871: Fixed a crash when deallocate deep ElementTree.

* bpo-19542: Fix bugs in WeakValueDictionary.setdefault() and
  WeakValueDictionary.pop() when a GC collection happens in another
  thread.

* bpo-20191: Fixed a crash in resource.prlimit() when passing a
  sequence that doesn’t own its elements as limits.

* bpo-28779: multiprocessing.set_forkserver_preload() would crash the
  forkserver process if a preloaded module instantiated some
  multiprocessing objects such as locks.

* bpo-28847: dbm.dumb now supports reading read-only files and no
  longer writes the index file when it is not changed.

* bpo-26937: The chown() method of the tarfile.TarFile class does not
  fail now when the grp module cannot be imported, as for example on
  Android platforms.


IDLE
----

* bpo-29071: IDLE colors f-string prefixes (but not invalid ur
  prefixes).

* bpo-28572: Add 10% to coverage of IDLE’s test_configdialog. Update
  and augment description of the configuration system.


Windows
-------

* bpo-29579: Removes readme.txt from the installer

* bpo-29326: Ignores blank lines in ._pth files (Patch by Alexey
  Izbyshev)

* bpo-28164: Correctly handle special console filenames (patch by Eryk
  Sun)

* bpo-29409: Implement **PEP 529** for io.FileIO (Patch by Eryk Sun)

* bpo-29392: Prevent crash when passing invalid arguments into msvcrt
  module.

* bpo-25778: winreg does not truncate string correctly (Patch by Eryk
  Sun)

* bpo-28896: Deprecate WindowsRegistryFinder and disable it by
  default.


C API
-----

* bpo-27867: Function PySlice_GetIndicesEx() is replaced with a macro
  if Py_LIMITED_API is not set or set to the value between 0x03050400
  and 0x03060000 (not including) or 0x03060100 or higher.

* bpo-29083: Fixed the declaration of some public API functions.
  PyArg_VaParse() and PyArg_VaParseTupleAndKeywords() were not
  available in limited API. PyArg_ValidateKeywordArguments(),
  PyArg_UnpackTuple() and Py_BuildValue() were not available in
  limited API of version < 3.3 when PY_SSIZE_T_CLEAN is defined.

* bpo-29058: All stable API extensions added after Python 3.2 are now
  available only when Py_LIMITED_API is set to the PY_VERSION_HEX
  value of the minimum Python version supporting this API.


Documentation
-------------

* bpo-28929: Link the documentation to its source file on GitHub.

* bpo-25008: Document smtpd.py as effectively deprecated and add a
  pointer to aiosmtpd, a third-party asyncio-based replacement.

* bpo-26355: Add canonical header link on each page to corresponding
  major version of the documentation. Patch by Matthias Bussonnier.

* bpo-29349: Fix Python 2 syntax in code for building the
  documentation.


Tests
-----

* bpo-28087: Skip test_asyncore and test_eintr poll failures on macOS.
  Skip some tests of select.poll when running on macOS due to
  unresolved issues with the underlying system poll function on some
  macOS versions.

* bpo-29571: to match the behaviour of the "re.LOCALE" flag,
  test_re.test_locale_flag now uses
  "locale.getpreferredencoding(False)" to determine the candidate
  encoding for the test regex (allowing it to correctly skip the test
  when the default locale encoding is a multi-byte encoding)

* bpo-28950: Disallow -j0 to be combined with -T/-l in regrtest
  command line arguments.

* bpo-28683: Fix the tests that bind() a unix socket and raise
  PermissionError on Android for a non-root user.

* bpo-26939: Add the support.setswitchinterval() function to fix
  test_functools hanging on the Android armv7 qemu emulator.


Build
-----

* bpo-27593: sys.version and the platform module python_build(),
  python_branch(), and python_revision() functions now use git
  information rather than hg when building from a repo.

* bpo-29572: Update Windows build and OS X installers to use OpenSSL
  1.0.2k.

* bpo-26851: Set Android compilation and link flags.

* bpo-28768: Fix implicit declaration of function _setmode. Patch by
  Masayuki Yamamoto

* bpo-29080: Removes hard dependency on hg.exe from PCBuild/build.bat

* bpo-23903: Added missed names to PC/python3.def.

* bpo-28762: lockf() is available on Android API level 24, but the
  F_LOCK macro is not defined in android-ndk-r13.

* bpo-28538: Fix the compilation error that occurs because
  if_nameindex() is available on Android API level 24, but the
  if_nameindex structure is not defined.

* bpo-20211: Do not add the directory for installing C header files
  and the directory for installing object code libraries to the cross
  compilation search paths. Original patch by Thomas Petazzoni.

* bpo-28849: Do not define sys.implementation._multiarch on Android.


Python 3.6.0 final
==================

*Release date: 2016-12-23*

No changes since release candidate 2


Python 3.6.0 release candidate 2
================================

*Release date: 2016-12-16*


Core and Builtins
-----------------

* bpo-28147: Fix a memory leak in split-table dictionaries: setattr()
  must not convert combined table into split table. Patch written by
  INADA Naoki.

* bpo-28990: Fix asyncio SSL hanging if connection is closed before
  handshake is completed. (Patch by HoHo-Ho)


Tools/Demos
-----------

* bpo-28770: Fix python-gdb.py for fastcalls.


Windows
-------

* bpo-28896: Deprecate WindowsRegistryFinder.


Build
-----

* bpo-28898: Prevent gdb build errors due to HAVE_LONG_LONG
  redefinition.


Python 3.6.0 release candidate 1
================================

*Release date: 2016-12-06*


Core and Builtins
-----------------

* bpo-23722: Rather than silently producing a class that doesn’t
  support zero-argument "super()" in methods, failing to pass the new
  "__classcell__" namespace entry up to "type.__new__" now results in
  a "DeprecationWarning" and a class that supports zero-argument
  "super()".

* bpo-28797: Modifying the class __dict__ inside the __set_name__
  method of a descriptor that is used inside that class no longer
  prevents calling the __set_name__ method of other descriptors.

* bpo-28782: Fix a bug in the implementation "yield from" when
  checking if the next instruction is YIELD_FROM. Regression
  introduced by WORDCODE (bpo-26647).


Library
-------

* bpo-27030: Unknown escapes in re.sub() replacement template are
  allowed again.  But they still are deprecated and will be disabled
  in 3.7.

* bpo-28835: Fix a regression introduced in warnings.catch_warnings():
  call warnings.showwarning() if it was overridden inside the context
  manager.

* bpo-27172: To assist with upgrades from 2.7, the previously
  documented deprecation of "inspect.getfullargspec()" has been
  reversed. This decision may be revisited again after the Python 2.7
  branch is no longer officially supported.

* bpo-26273: Add new "socket.TCP_CONGESTION" (Linux 2.6.13) and
  "socket.TCP_USER_TIMEOUT" (Linux 2.6.37) constants. Patch written by
  Omar Sandoval.

* bpo-24142: Reading a corrupt config file left configparser in an
  invalid state. Original patch by Florian Höch.

* bpo-28843: Fix asyncio C Task to handle exceptions __traceback__.


C API
-----

* bpo-28808: PyUnicode_CompareWithASCIIString() now never raises
  exceptions.


Documentation
-------------

* bpo-23722: The data model reference and the porting section in the
  What’s New guide now cover the additional "__classcell__" handling
  needed for custom metaclasses to fully support **PEP 487** and zero-
  argument "super()".


Tools/Demos
-----------

* bpo-28023: Fix python-gdb.py didn’t support new dict implementation.


Python 3.6.0 beta 4
===================

*Release date: 2016-11-21*


Core and Builtins
-----------------

* bpo-28532: Show sys.version when -V option is supplied twice.

* bpo-27100: The with-statement now checks for __enter__ before it
  checks for __exit__. This gives less confusing error messages when
  both methods are missing. Patch by Jonathan Ellington.

* bpo-28746: Fix the set_inheritable() file descriptor method on
  platforms that do not have the ioctl FIOCLEX and FIONCLEX commands.

* bpo-26920: Fix not getting the locale’s charset upon initializing
  the interpreter, on platforms that do not have langinfo.

* bpo-28648: Fixed crash in Py_DecodeLocale() in debug build on Mac OS
  X when decode astral characters.  Patch by Xiang Zhang.

* bpo-19398: Extra slash no longer added to sys.path components in
  case of empty compile-time PYTHONPATH components.

* bpo-28665: Improve speed of the STORE_DEREF opcode by 40%.

* bpo-28583: PyDict_SetDefault didn’t combine split table when needed.
  Patch by Xiang Zhang.

* bpo-27243: Change PendingDeprecationWarning -> DeprecationWarning.
  As it was agreed in the issue, __aiter__ returning an awaitable
  should result in PendingDeprecationWarning in 3.5 and in
  DeprecationWarning in 3.6.

* bpo-26182: Fix a refleak in code that raises DeprecationWarning.

* bpo-28721: Fix asynchronous generators aclose() and athrow() to
  handle StopAsyncIteration propagation properly.


Library
-------

* bpo-28752: Restored the __reduce__() methods of datetime objects.

* bpo-28727: Regular expression patterns, _sre.SRE_Pattern objects
  created by re.compile(), become comparable (only x==y and x!=y
  operators). This change should fix the bpo-18383: don’t duplicate
  warning filters when the warnings module is reloaded (thing usually
  only done in unit tests).

* bpo-20572: The subprocess.Popen.wait method’s undocumented endtime
  parameter now raises a DeprecationWarning.

* bpo-25659: In ctypes, prevent a crash calling the from_buffer() and
  from_buffer_copy() methods on abstract classes like Array.

* bpo-19717: Makes Path.resolve() succeed on paths that do not exist.
  Patch by Vajrasky Kok

* bpo-28563: Fixed possible DoS and arbitrary code execution when
  handle plural form selections in the gettext module.  The expression
  parser now supports exact syntax supported by GNU gettext.

* bpo-28387: Fixed possible crash in _io.TextIOWrapper deallocator
  when the garbage collector is invoked in other thread.  Based on
  patch by Sebastian Cufre.

* bpo-28600: Optimize loop.call_soon.

* bpo-28613: Fix get_event_loop() return the current loop if called
  from coroutines/callbacks.

* bpo-28634: Fix asyncio.isfuture() to support unittest.Mock.

* bpo-26081: Fix refleak in _asyncio.Future.__iter__().throw.

* bpo-28639: Fix inspect.isawaitable to always return bool Patch by
  Justin Mayfield.

* bpo-28652: Make loop methods reject socket kinds they do not
  support.

* bpo-28653: Fix a refleak in functools.lru_cache.

* bpo-28703: Fix asyncio.iscoroutinefunction to handle Mock objects.

* bpo-28704: Fix create_unix_server to support Path-like objects (PEP
  519).

* bpo-28720: Add collections.abc.AsyncGenerator.


Documentation
-------------

* bpo-28513: Documented command-line interface of zipfile.


Tests
-----

* bpo-28666: Now test.support.rmtree is able to remove unwritable or
  unreadable directories.

* bpo-23839: Various caches now are cleared before running every test
  file.


Build
-----

* bpo-10656: Fix out-of-tree building on AIX.  Patch by Tristan Carel
  and Michael Haubenwallner.

* bpo-26359: Rename –with-optimiations to –enable-optimizations.

* bpo-28676: Prevent missing ‘getentropy’ declaration warning on
  macOS. Patch by Gareth Rees.


Python 3.6.0 beta 3
===================

*Release date: 2016-10-31*


Core and Builtins
-----------------

* bpo-28128: Deprecation warning for invalid str and byte escape
  sequences now prints better information about where the error
  occurs. Patch by Serhiy Storchaka and Eric Smith.

* bpo-28509: dict.update() no longer allocate unnecessary large
  memory.

* bpo-28426: Fixed potential crash in PyUnicode_AsDecodedObject() in
  debug build.

* bpo-28517: Fixed of-by-one error in the peephole optimizer that
  caused keeping unreachable code.

* bpo-28214: Improved exception reporting for problematic __set_name__
  attributes.

* bpo-23782: Fixed possible memory leak in _PyTraceback_Add() and
  exception loss in PyTraceBack_Here().

* bpo-28471: Fix “Python memory allocator called without holding the
  GIL” crash in socket.setblocking.


Library
-------

* bpo-27517: LZMA compressor and decompressor no longer raise
  exceptions if given empty data twice.  Patch by Benjamin Fogle.

* bpo-28549: Fixed segfault in curses’s addch() with ncurses6.

* bpo-28449: tarfile.open() with mode “r” or “r:” now tries to open a
  tar file with compression before trying to open it without
  compression. Otherwise it had 50% chance failed with
  ignore_zeros=True.

* bpo-23262: The webbrowser module now supports Firefox 36+ and
  derived browsers.  Based on patch by Oleg Broytman.

* bpo-27939: Fixed bugs in tkinter.ttk.LabeledScale and tkinter.Scale
  caused by representing the scale as float value internally in Tk.
  tkinter.IntVar now works if float value is set to underlying Tk
  variable.

* bpo-18844: The various ways of specifying weights for
  random.choices() now produce the same result sequences.

* bpo-28255: calendar.TextCalendar().prmonth() no longer prints a
  space at the start of new line after printing a month’s calendar.
  Patch by Xiang Zhang.

* bpo-20491: The textwrap.TextWrapper class now honors non-breaking
  spaces. Based on patch by Kaarle Ritvanen.

* bpo-28353: os.fwalk() no longer fails on broken links.

* bpo-28430: Fix iterator of C implemented asyncio.Future doesn’t
  accept non-None value is passed to it.send(val).

* bpo-27025: Generated names for Tkinter widgets now start by the “!”
  prefix for readability.

* bpo-25464: Fixed HList.header_exists() in tkinter.tix module by
  addin a workaround to Tix library bug.

* bpo-28488: shutil.make_archive() no longer adds entry “./” to ZIP
  archive.

* bpo-25953: re.sub() now raises an error for invalid numerical group
  reference in replacement template even if the pattern is not found
  in the string.  Error message for invalid group reference now
  includes the group index and the position of the reference. Based on
  patch by SilentGhost.

* bpo-18219: Optimize csv.DictWriter for large number of columns.
  Patch by Mariatta Wijaya.

* bpo-28448: Fix C implemented asyncio.Future didn’t work on Windows.

* bpo-28480: Fix error building socket module when multithreading is
  disabled.

* bpo-24452: Make webbrowser support Chrome on Mac OS X.

* bpo-20766: Fix references leaked by pdb in the handling of SIGINT
  handlers.

* bpo-28492: Fix how StopIteration exception is raised in
  _asyncio.Future.

* bpo-28500: Fix asyncio to handle async gens GC from another thread.

* bpo-26923: Fix asyncio.Gather to refuse being cancelled once all
  children are done. Patch by Johannes Ebke.

* bpo-26796: Don’t configure the number of workers for default
  threadpool executor. Initial patch by Hans Lawrenz.

* bpo-28544: Implement asyncio.Task in C.


Windows
-------

* bpo-28522: Fixes mishandled buffer reallocation in getpathp.c


Build
-----

* bpo-28444: Fix missing extensions modules when cross compiling.

* bpo-28208: Update Windows build and OS X installers to use SQLite
  3.14.2.

* bpo-28248: Update Windows build and OS X installers to use OpenSSL
  1.0.2j.


Tests
-----

* bpo-26944: Fix test_posix for Android where ‘id -G’ is entirely
  wrong or missing the effective gid.

* bpo-28409: regrtest: fix the parser of command line arguments.


Python 3.6.0 beta 2
===================

*Release date: 2016-10-10*


Core and Builtins
-----------------

* bpo-28183: Optimize and cleanup dict iteration.

* bpo-26081: Added C implementation of asyncio.Future. Original patch
  by Yury Selivanov.

* bpo-28379: Added sanity checks and tests for
  PyUnicode_CopyCharacters(). Patch by Xiang Zhang.

* bpo-28376: The type of long range iterator is now registered as
  Iterator. Patch by Oren Milman.

* bpo-28376: Creating instances of range_iterator by calling
  range_iterator type now is deprecated.  Patch by Oren Milman.

* bpo-28376: The constructor of range_iterator now checks that step is
  not 0. Patch by Oren Milman.

* bpo-26906: Resolving special methods of uninitialized type now
  causes implicit initialization of the type instead of a fail.

* bpo-18287: PyType_Ready() now checks that tp_name is not NULL.
  Original patch by Niklas Koep.

* bpo-24098: Fixed possible crash when AST is changed in process of
  compiling it.

* bpo-28201: Dict reduces possibility of 2nd conflict in hash table
  when hashes have same lower bits.

* bpo-28350: String constants with null character no longer interned.

* bpo-26617: Fix crash when GC runs during weakref callbacks.

* bpo-27942: String constants now interned recursively in tuples and
  frozensets.

* bpo-21578: Fixed misleading error message when ImportError called
  with invalid keyword args.

* bpo-28203: Fix incorrect type in complex(1.0, {2:3}) error message.
  Patch by Soumya Sharma.

* bpo-28086: Single var-positional argument of tuple subtype was
  passed unscathed to the C-defined function.  Now it is converted to
  exact tuple.

* bpo-28214: Now __set_name__ is looked up on the class instead of the
  instance.

* bpo-27955: Fallback on reading /dev/urandom device when the
  getrandom() syscall fails with EPERM, for example when blocked by
  SECCOMP.

* bpo-28192: Don’t import readline in isolated mode.

* Upgrade internal unicode databases to Unicode version 9.0.0.

* bpo-28131: Fix a regression in zipimport’s compile_source().
  zipimport should use the same optimization level as the interpreter.

* bpo-28126: Replace Py_MEMCPY with memcpy(). Visual Studio can
  properly optimize memcpy().

* bpo-28120: Fix dict.pop() for splitted dictionary when trying to
  remove a “pending key” (Not yet inserted in split-table). Patch by
  Xiang Zhang.

* bpo-26182: Raise DeprecationWarning when async and await keywords
  are used as variable/attribute/class/function name.


Library
-------

* bpo-27998: Fixed bytes path support in os.scandir() on Windows.
  Patch by Eryk Sun.

* bpo-28317: The disassembler now decodes FORMAT_VALUE argument.

* bpo-26293: Fixed writing ZIP files that starts not from the start of
  the file.  Offsets in ZIP file now are relative to the start of the
  archive in conforming to the specification.

* bpo-28380: unittest.mock Mock autospec functions now properly
  support assert_called, assert_not_called, and assert_called_once.

* bpo-27181: remove statistics.geometric_mean and defer until 3.7.

* bpo-28229: lzma module now supports pathlib.

* bpo-28321: Fixed writing non-BMP characters with binary format in
  plistlib.

* bpo-28225: bz2 module now supports pathlib.  Initial patch by Ethan
  Furman.

* bpo-28227: gzip now supports pathlib.  Patch by Ethan Furman.

* bpo-27358: Optimized merging var-keyword arguments and improved
  error message when passing a non-mapping as a var-keyword argument.

* bpo-28257: Improved error message when passing a non-iterable as a
  var-positional argument.  Added opcode BUILD_TUPLE_UNPACK_WITH_CALL.

* bpo-28322: Fixed possible crashes when unpickle itertools objects
  from incorrect pickle data.  Based on patch by John Leitch.

* bpo-28228: imghdr now supports pathlib.

* bpo-28226: compileall now supports pathlib.

* bpo-28314: Fix function declaration (C flags) for the getiterator()
  method of xml.etree.ElementTree.Element.

* bpo-28148: Stop using localtime() and gmtime() in the time module.
  Introduced platform independent _PyTime_localtime API that is
  similar to POSIX localtime_r, but available on all platforms.  Patch
  by Ed Schouten.

* bpo-28253: Fixed calendar functions for extreme months: 0001-01 and
  9999-12. Methods itermonthdays() and itermonthdays2() are
  reimplemented so that they don’t call itermonthdates() which can
  cause datetime.date under/overflow.

* bpo-28275: Fixed possible use after free in the decompress() methods
  of the LZMADecompressor and BZ2Decompressor classes. Original patch
  by John Leitch.

* bpo-27897: Fixed possible crash in
  sqlite3.Connection.create_collation() if pass invalid string-like
  object as a name.  Patch by Xiang Zhang.

* bpo-18844: random.choices() now has k as a keyword-only argument to
  improve the readability of common cases and come into line with the
  signature used in other languages.

* bpo-18893: Fix invalid exception handling in
  Lib/ctypes/macholib/dyld.py. Patch by Madison May.

* bpo-27611: Fixed support of default root window in the tkinter.tix
  module. Added the master parameter in the DisplayStyle constructor.

* bpo-27348: In the traceback module, restore the formatting of
  exception messages like “Exception: None”.  This fixes a regression
  introduced in 3.5a2.

* bpo-25651: Allow falsy values to be used for msg parameter of
  subTest().

* bpo-27778: Fix a memory leak in os.getrandom() when the getrandom()
  is interrupted by a signal and a signal handler raises a Python
  exception.

* bpo-28200: Fix memory leak on Windows in the os module (fix
  path_converter() function).

* bpo-25400: RobotFileParser now correctly returns default values for
  crawl_delay and request_rate.  Initial patch by Peter Wirtz.

* bpo-27932: Prevent memory leak in win32_ver().

* Fix UnboundLocalError in socket._sendfile_use_sendfile.

* bpo-28075: Check for ERROR_ACCESS_DENIED in Windows implementation
  of os.stat().  Patch by Eryk Sun.

* bpo-22493: Warning message emitted by using inline flags in the
  middle of regular expression now contains a (truncated) regex
  pattern. Patch by Tim Graham.

* bpo-25270: Prevent codecs.escape_encode() from raising SystemError
  when an empty bytestring is passed.

* bpo-28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.

* bpo-25895: Enable WebSocket URL schemes in urllib.parse.urljoin.
  Patch by Gergely Imreh and Markus Holtermann.

* bpo-28114: Fix a crash in parse_envlist() when env contains byte
  strings. Patch by Eryk Sun.

* bpo-27599: Fixed buffer overrun in binascii.b2a_qp() and
  binascii.a2b_qp().

* bpo-27906: Fix socket accept exhaustion during high TCP traffic.
  Patch by Kevin Conway.

* bpo-28174: Handle when SO_REUSEPORT isn’t properly supported. Patch
  by Seth Michael Larson.

* bpo-26654: Inspect functools.partial in asyncio.Handle.__repr__.
  Patch by iceboy.

* bpo-26909: Fix slow pipes IO in asyncio. Patch by INADA Naoki.

* bpo-28176: Fix callbacks race in asyncio.SelectorLoop.sock_connect.

* bpo-27759: Fix selectors incorrectly retain invalid file
  descriptors. Patch by Mark Williams.

* bpo-28368: Refuse monitoring processes if the child watcher has no
  loop attached. Patch by Vincent Michel.

* bpo-28369: Raise RuntimeError when transport’s FD is used with
  add_reader, add_writer, etc.

* bpo-28370: Speedup asyncio.StreamReader.readexactly. Patch by
  Коренберг Марк.

* bpo-28371: Deprecate passing asyncio.Handles to run_in_executor.

* bpo-28372: Fix asyncio to support formatting of non-python
  coroutines.

* bpo-28399: Remove UNIX socket from FS before binding. Patch by
  Коренберг Марк.

* bpo-27972: Prohibit Tasks to await on themselves.


Windows
-------

* bpo-28402: Adds signed catalog files for stdlib on Windows.

* bpo-28333: Enables Unicode for ps1/ps2 and input() prompts. (Patch
  by Eryk Sun)

* bpo-28251: Improvements to help manuals on Windows.

* bpo-28110: launcher.msi has different product codes between 32-bit
  and 64-bit

* bpo-28161: Opening CON for write access fails

* bpo-28162: WindowsConsoleIO readall() fails if first line starts
  with Ctrl+Z

* bpo-28163: WindowsConsoleIO fileno() passes wrong flags to
  _open_osfhandle

* bpo-28164: _PyIO_get_console_type fails for various paths

* bpo-28137: Renames Windows path file to ._pth

* bpo-28138: Windows ._pth file should allow import site


C API
-----

* bpo-28426: Deprecated undocumented functions
  PyUnicode_AsEncodedObject(), PyUnicode_AsDecodedObject(),
  PyUnicode_AsDecodedUnicode() and PyUnicode_AsEncodedUnicode().


Build
-----

* bpo-28258: Fixed build with Estonian locale (python-config and
  distclean targets in Makefile).  Patch by Arfrever Frehtes Taifersar
  Arahesis.

* bpo-26661: setup.py now detects system libffi with multiarch
  wrapper.

* bpo-15819: Remove redundant include search directory option for
  building outside the source tree.


Tests
-----

* bpo-28217: Adds _testconsole module to test console input.


Python 3.6.0 beta 1
===================

*Release date: 2016-09-12*


Core and Builtins
-----------------

* bpo-23722: The __class__ cell used by zero-argument super() is now
  initialized from type.__new__ rather than __build_class__, so class
  methods relying on that will now work correctly when called from
  metaclass methods during class creation. Patch by Martin Teichmann.

* bpo-25221: Fix corrupted result from PyLong_FromLong(0) when Python
  is compiled with NSMALLPOSINTS = 0.

* bpo-27080: Implement formatting support for **PEP 515**.  Initial
  patch by Chris Angelico.

* bpo-27199: In tarfile, expose copyfileobj bufsize to improve
  throughput. Patch by Jason Fried.

* bpo-27948: In f-strings, only allow backslashes inside the braces
  (where the expressions are).  This is a breaking change from the 3.6
  alpha releases, where backslashes are allowed anywhere in an
  f-string.  Also, require that expressions inside f-strings be
  enclosed within literal braces, and not escapes like
  "f'\x7b"hi"\x7d'".

* bpo-28046: Remove platform-specific directories from sys.path.

* bpo-28071: Add early-out for differencing from an empty set.

* bpo-25758: Prevents zipimport from unnecessarily encoding a filename
  (patch by Eryk Sun)

* bpo-25856: The __module__ attribute of extension classes and
  functions now is interned. This leads to more compact pickle data
  with protocol 4.

* bpo-27213: Rework CALL_FUNCTION* opcodes to produce shorter and more
  efficient bytecode. Patch by Demur Rumed, design by Serhiy
  Storchaka, reviewed by Serhiy Storchaka and Victor Stinner.

* bpo-26331: Implement tokenizing support for **PEP 515**. Patch by
  Georg Brandl.

* bpo-27999: Make “global after use” a SyntaxError, and ditto for
  nonlocal. Patch by Ivan Levkivskyi.

* bpo-28003: Implement **PEP 525** – Asynchronous Generators.

* bpo-27985: Implement **PEP 526** – Syntax for Variable Annotations.
  Patch by Ivan Levkivskyi.

* bpo-26058: Add a new private version to the builtin dict type,
  incremented at each dictionary creation and at each dictionary
  change. Implementation of the PEP 509.

* bpo-27364: A backslash-character pair that is not a valid escape
  sequence now generates a DeprecationWarning.  Patch by Emanuel
  Barry.

* bpo-27350: "dict" implementation is changed like PyPy. It is more
  compact and preserves insertion order. (Concept developed by Raymond
  Hettinger and patch by Inada Naoki.)

* bpo-27911: Remove unnecessary error checks in
  "exec_builtin_or_dynamic()".

* bpo-27078: Added BUILD_STRING opcode.  Optimized f-strings
  evaluation.

* bpo-17884: Python now requires systems with inttypes.h and stdint.h

* bpo-27961: Require platforms to support "long long". Python hasn’t
  compiled without "long long" for years, so this is basically a
  formality.

* bpo-27355: Removed support for Windows CE.  It was never finished,
  and Windows CE is no longer a relevant platform for Python.

* Implement **PEP 523**.

* bpo-27870: A left shift of zero by a large integer no longer
  attempts to allocate large amounts of memory.

* bpo-25402: In int-to-decimal-string conversion, improve the estimate
  of the intermediate memory required, and remove an unnecessarily
  strict overflow check. Patch by Serhiy Storchaka.

* bpo-27214: In long_invert, be more careful about modifying object
  returned by long_add, and remove an unnecessary check for small
  longs. Thanks Oren Milman for analysis and patch.

* bpo-27506: Support passing the bytes/bytearray.translate() “delete”
  argument by keyword.

* bpo-27812: Properly clear out a generator’s frame’s backreference to
  the generator to prevent crashes in frame.clear().

* bpo-27811: Fix a crash when a coroutine that has not been awaited is
  finalized with warnings-as-errors enabled.

* bpo-27587: Fix another issue found by PVS-Studio: Null pointer check
  after use of ‘def’ in _PyState_AddModule(). Initial patch by
  Christian Heimes.

* bpo-27792: The modulo operation applied to "bool" and other "int"
  subclasses now always returns an "int". Previously the return type
  depended on the input values. Patch by Xiang Zhang.

* bpo-26984: int() now always returns an instance of exact int.

* bpo-25604: Fix a minor bug in integer true division; this bug could
  potentially have caused off-by-one-ulp results on platforms with
  unreliable ldexp implementations.

* bpo-24254: Make class definition namespace ordered by default.

* bpo-27662: Fix an overflow check in "List_New": the original code
  was checking against "Py_SIZE_MAX" instead of the correct upper
  bound of "Py_SSIZE_T_MAX". Patch by Xiang Zhang.

* bpo-27782: Multi-phase extension module import now correctly allows
  the "m_methods" field to be used to add module level functions to
  instances of non-module types returned from "Py_create_mod". Patch
  by Xiang Zhang.

* bpo-27936: The round() function accepted a second None argument for
  some types but not for others.  Fixed the inconsistency by accepting
  None for all numeric types.

* bpo-27487: Warn if a submodule argument to “python -m” or
  runpy.run_module() is found in sys.modules after parent packages are
  imported, but before the submodule is executed.

* bpo-27157: Make only type() itself accept the one-argument form.
  Patch by Eryk Sun and Emanuel Barry.

* bpo-27558: Fix a SystemError in the implementation of “raise”
  statement. In a brand new thread, raise a RuntimeError since there
  is no active exception to reraise. Patch written by Xiang Zhang.

* bpo-28008: Implement **PEP 530** – asynchronous comprehensions.

* bpo-27942: Fix memory leak in codeobject.c


Library
-------

* bpo-28732: Fix crash in os.spawnv() with no elements in args

* bpo-28485: Always raise ValueError for negative
  compileall.compile_dir(workers=…) parameter, even when
  multithreading is unavailable.

* bpo-28037: Use sqlite3_get_autocommit() instead of setting
  Connection->inTransaction manually.

* bpo-25283: Attributes tm_gmtoff and tm_zone are now available on all
  platforms in the return values of time.localtime() and
  time.gmtime().

* bpo-24454: Regular expression match object groups are now accessible
  using __getitem__. “mo[x]” is equivalent to “mo.group(x)”.

* bpo-10740: sqlite3 no longer implicitly commit an open transaction
  before DDL statements.

* bpo-17941: Add a *module* parameter to collections.namedtuple().

* bpo-22493: Inline flags now should be used only at the start of the
  regular expression. Deprecation warning is emitted if uses them in
  the middle of the regular expression.

* bpo-26885: xmlrpc now supports unmarshalling additional data types
  used by Apache XML-RPC implementation for numerics and None.

* bpo-28070: Fixed parsing inline verbose flag in regular expressions.

* bpo-19500: Add client-side SSL session resumption to the ssl module.

* bpo-28022: Deprecate ssl-related arguments in favor of SSLContext.
  The deprecation include manual creation of SSLSocket and
  certfile/keyfile (or similar) in ftplib, httplib, imaplib, smtplib,
  poplib and urllib.

* bpo-28043: SSLContext has improved default settings: OP_NO_SSLv2,
  OP_NO_SSLv3, OP_NO_COMPRESSION, OP_CIPHER_SERVER_PREFERENCE,
  OP_SINGLE_DH_USE, OP_SINGLE_ECDH_USE and HIGH ciphers without MD5.

* bpo-24693: Changed some RuntimeError’s in the zipfile module to more
  appropriate types. Improved some error messages and debugging
  output.

* bpo-17909: "json.load" and "json.loads" now support binary input
  encoded as UTF-8, UTF-16 or UTF-32. Patch by Serhiy Storchaka.

* bpo-27137: the pure Python fallback implementation of
  "functools.partial" now matches the behaviour of its accelerated C
  counterpart for subclassing, pickling and text representation
  purposes. Patch by Emanuel Barry and Serhiy Storchaka.

* Fix possible integer overflows and crashes in the mmap module with
  unusual usage patterns.

* bpo-1703178: Fix the ability to pass the –link-objects option to the
  distutils build_ext command.

* bpo-28019: itertools.count() no longer rounds non-integer step in
  range between 1.0 and 2.0 to 1.

* bpo-18401: Pdb now supports the ‘readrc’ keyword argument to control
  whether .pdbrc files should be read.  Patch by Martin Matusiak and
  Sam Kimbrel.

* bpo-25969: Update the lib2to3 grammar to handle the unpacking
  generalizations added in 3.5.

* bpo-14977: mailcap now respects the order of the lines in the
  mailcap files (“first match”), as required by RFC 1542.  Patch by
  Michael Lazar.

* bpo-28082: Convert re flag constants to IntFlag.

* bpo-28025: Convert all ssl module constants to IntEnum and IntFlags.
  SSLContext properties now return flags and enums.

* bpo-23591: Add Flag, IntFlag, and auto() to enum module.

* bpo-433028: Added support of modifier spans in regular expressions.

* bpo-24594: Validates persist parameter when opening MSI database

* bpo-17582: xml.etree.ElementTree nows preserves whitespaces in
  attributes (Patch by Duane Griffin.  Reviewed and approved by Stefan
  Behnel.)

* bpo-28047: Fixed calculation of line length used for the base64 CTE
  in the new email policies.

* bpo-27576: Fix call order in OrderedDict.__init__().

* email.generator.DecodedGenerator now supports the policy keyword.

* bpo-28027: Remove undocumented modules from "Lib/plat-*": IN, CDROM,
  DLFCN, TYPES, CDIO, and STROPTS.

* bpo-27445: Don’t pass str(_charset) to MIMEText.set_payload(). Patch
  by Claude Paroz.

* bpo-24277: The new email API is no longer provisional, and the docs
  have been reorganized and rewritten to emphasize the new API.

* bpo-22450: urllib now includes an "Accept: */*" header among the
  default headers. This makes the results of REST API requests more
  consistent and predictable especially when proxy servers are
  involved.

* lib2to3.pgen3.driver.load_grammar() now creates a stable cache file
  between runs given the same Grammar.txt input regardless of the hash
  randomization setting.

* bpo-28005: Allow ImportErrors in encoding implementation to
  propagate.

* bpo-26667: Support path-like objects in importlib.util.

* bpo-27570: Avoid zero-length memcpy() etc calls with null source
  pointers in the “ctypes” and “array” modules.

* bpo-22233: Break email header lines *only* on the RFC specified CR
  and LF characters, not on arbitrary unicode line breaks.  This also
  fixes a bug in HTTP header parsing.

* bpo-27331: The email.mime classes now all accept an optional policy
  keyword.

* bpo-27988: Fix email iter_attachments incorrect mutation of payload
  list.

* bpo-16113: Add SHA-3 and SHAKE support to hashlib module.

* Eliminate a tautological-pointer-compare warning in _scproxy.c.

* bpo-27776: The "os.urandom()" function does now block on Linux 3.17
  and newer until the system urandom entropy pool is initialized to
  increase the security. This change is part of the **PEP 524**.

* bpo-27778: Expose the Linux "getrandom()" syscall as a new
  "os.getrandom()" function. This change is part of the **PEP 524**.

* bpo-27691: Fix ssl module’s parsing of GEN_RID subject alternative
  name fields in X.509 certs.

* bpo-18844: Add random.choices().

* bpo-25761: Improved error reporting about truncated pickle data in C
  implementation of unpickler.  UnpicklingError is now raised instead
  of AttributeError and ValueError in some cases.

* bpo-26798: Add BLAKE2 (blake2b and blake2s) to hashlib.

* bpo-26032: Optimized globbing in pathlib by using os.scandir(); it
  is now about 1.5–4 times faster.

* bpo-25596: Optimized glob() and iglob() functions in the glob
  module; they are now about 3–6 times faster.

* bpo-27928: Add scrypt (password-based key derivation function) to
  hashlib module (requires OpenSSL 1.1.0).

* bpo-27850: Remove 3DES from ssl module’s default cipher list to
  counter measure sweet32 attack (CVE-2016-2183).

* bpo-27766: Add ChaCha20 Poly1305 to ssl module’s default cipher
  list. (Required OpenSSL 1.1.0 or LibreSSL).

* bpo-25387: Check return value of winsound.MessageBeep.

* bpo-27866: Add SSLContext.get_ciphers() method to get a list of all
  enabled ciphers.

* bpo-27744: Add AF_ALG (Linux Kernel crypto) to socket module.

* bpo-26470: Port ssl and hashlib module to OpenSSL 1.1.0.

* bpo-11620: Fix support for SND_MEMORY in winsound.PlaySound.  Based
  on a patch by Tim Lesher.

* bpo-11734: Add support for IEEE 754 half-precision floats to the
  struct module. Based on a patch by Eli Stevens.

* bpo-27919: Deprecated "extra_path" distribution option in distutils
  packaging.

* bpo-23229: Add new "cmath" constants: "cmath.inf" and "cmath.nan" to
  match "math.inf" and "math.nan", and also "cmath.infj" and
  "cmath.nanj" to match the format used by complex repr.

* bpo-27842: The csv.DictReader now returns rows of type OrderedDict.
  (Contributed by Steve Holden.)

* Remove support for passing a file descriptor to os.access. It never
  worked but previously didn’t raise.

* bpo-12885: Fix error when distutils encounters symlink.

* bpo-27881: Fixed possible bugs when setting
  sqlite3.Connection.isolation_level. Based on patch by Xiang Zhang.

* bpo-27861: Fixed a crash in sqlite3.Connection.cursor() when a
  factory creates not a cursor.  Patch by Xiang Zhang.

* bpo-19884: Avoid spurious output on OS X with Gnu Readline.

* bpo-27706: Restore deterministic behavior of random.Random().seed()
  for string seeds using seeding version 1.  Allows sequences of calls
  to random() to exactly match those obtained in Python 2. Patch by
  Nofar Schnider.

* bpo-10513: Fix a regression in Connection.commit().  Statements
  should not be reset after a commit.

* bpo-12319: Chunked transfer encoding support added to
  http.client.HTTPConnection requests.  The
  urllib.request.AbstractHTTPHandler class does not enforce a Content-
  Length header any more.  If a HTTP request has a file or iterable
  body, but no Content-Length header, the library now falls back to
  use chunked transfer-encoding.

* A new version of typing.py from https://github.com/python/typing: -
  Collection (only for 3.6) (bpo-27598) - Add FrozenSet to __all__
  (upstream #261) - fix crash in _get_type_vars() (upstream #259) -
  Remove the dict constraint in ForwardRef._eval_type (upstream #252)

* bpo-27832: Make "_normalize" parameter to "Fraction" constructor
  keyword-only, so that "Fraction(2, 3, 4)" now raises "TypeError".

* bpo-27539: Fix unnormalised "Fraction.__pow__" result in the case of
  negative exponent and negative base.

* bpo-21718: cursor.description is now available for queries using
  CTEs.

* bpo-27819: In distutils sdists, simply produce the “gztar” (gzipped
  tar format) distributions on all platforms unless “formats” is
  supplied.

* bpo-2466: posixpath.ismount now correctly recognizes mount points
  which the user does not have permission to access.

* bpo-9998: On Linux, ctypes.util.find_library now looks in
  LD_LIBRARY_PATH for shared libraries.

* bpo-27573: exit message for code.interact is now configurable.

* bpo-27930: Improved behaviour of logging.handlers.QueueListener.
  Thanks to Paulo Andrade and Petr Viktorin for the analysis and
  patch.

* bpo-6766: Distributed reference counting added to multiprocessing to
  support nesting of shared values / proxy objects.

* bpo-21201: Improves readability of multiprocessing error message.
  Thanks to Wojciech Walczak for patch.

* asyncio: Add set_protocol / get_protocol to Transports.

* bpo-27456: asyncio: Set TCP_NODELAY by default.


IDLE
----

* bpo-15308: Add ‘interrupt execution’ (^C) to Shell menu. Patch by
  Roger Serwy, updated by Bayard Randel.

* bpo-27922: Stop IDLE tests from ‘flashing’ gui widgets on the
  screen.

* bpo-27891: Consistently group and sort imports within idlelib
  modules.

* bpo-17642: add larger font sizes for classroom projection.

* Add version to title of IDLE help window.

* bpo-25564: In section on IDLE – console differences, mention that
  using exec means that __builtins__ is defined for each statement.

* bpo-27821: Fix 3.6.0a3 regression that prevented custom key sets
  from being selected when no custom theme was defined.


C API
-----

* bpo-26900: Excluded underscored names and other private API from
  limited API.

* bpo-26027: Add support for path-like objects in
  PyUnicode_FSConverter() & PyUnicode_FSDecoder().


Tests
-----

* bpo-27427: Additional tests for the math module. Patch by Francisco
  Couzo.

* bpo-27953: Skip math and cmath tests that fail on OS X 10.4 due to a
  poor libm implementation of tan.

* bpo-26040: Improve test_math and test_cmath coverage and rigour.
  Patch by Jeff Allen.

* bpo-27787: Call gc.collect() before checking each test for “dangling
  threads”, since the dangling threads are weak references.


Build
-----

* bpo-27566: Fix clean target in freeze makefile (patch by Lisa Roach)

* bpo-27705: Update message in validate_ucrtbase.py

* bpo-27976: Deprecate building _ctypes with the bundled copy of
  libffi on non-OSX UNIX platforms.

* bpo-27983: Cause lack of llvm-profdata tool when using clang as
  required for PGO linking to be a configure time error rather than
  make time when "--with-optimizations" is enabled.  Also improve our
  ability to find the llvm-profdata tool on MacOS and some Linuxes.

* bpo-21590: Support for DTrace and SystemTap probes.

* bpo-26307: The profile-opt build now applies PGO to the built-in
  modules.

* bpo-26359: Add the –with-optimizations flag to turn on LTO and PGO
  build support when available.

* bpo-27917: Set platform triplets for Android builds.

* bpo-25825: Update references to the $(LIBPL) installation path on
  AIX. This path was changed in 3.2a4.

* Update OS X installer to use SQLite 3.14.1 and XZ 5.2.2.

* bpo-21122: Fix LTO builds on OS X.

* bpo-17128: Build OS X installer with a private copy of OpenSSL. Also
  provide a sample Install Certificates command script to install a
  set of root certificates from the third-party certifi module.


Tools/Demos
-----------

* bpo-27952: Get Tools/scripts/fixcid.py working with Python 3 and the
  current “re” module, avoid invalid Python backslash escapes, and fix
  a bug parsing escaped C quote signs.


Windows
-------

* bpo-28065: Update xz dependency to 5.2.2 and build it from source.

* bpo-25144: Ensures TargetDir is set before continuing with custom
  install.

* bpo-1602: Windows console doesn’t input or print Unicode (PEP 528)

* bpo-27781: Change file system encoding on Windows to UTF-8 (PEP 529)

* bpo-27731: Opt-out of MAX_PATH on Windows 10

* bpo-6135: Adds encoding and errors parameters to subprocess.

* bpo-27959: Adds oem encoding, alias ansi to mbcs, move aliasmbcs to
  codec lookup.

* bpo-27982: The functions of the winsound module now accept keyword
  arguments.

* bpo-20366: Build full text search support into SQLite on Windows.

* bpo-27756: Adds new icons for Python files and processes on Windows.
  Designs by Cherry Wang.

* bpo-27883: Update sqlite to 3.14.1.0 on Windows.


Python 3.6.0 alpha 4
====================

*Release date: 2016-08-15*


Core and Builtins
-----------------

* bpo-27704: Optimized creating bytes and bytearray from byte-like
  objects and iterables. Speed up to 3 times for short objects.
  Original patch by Naoki Inada.

* bpo-26823: Large sections of repeated lines in tracebacks are now
  abbreviated as “[Previous line repeated {count} more times]” by the
  builtin traceback rendering. Patch by Emanuel Barry.

* bpo-27574: Decreased an overhead of parsing keyword arguments in
  functions implemented with using Argument Clinic.

* bpo-22557: Now importing already imported modules is up to 2.5 times
  faster.

* bpo-17596: Include <wincrypt.h> to help with Min GW building.

* bpo-17599: On Windows, rename the privately defined
  REPARSE_DATA_BUFFER structure to avoid conflicting with the
  definition from Min GW.

* bpo-27507: Add integer overflow check in bytearray.extend().  Patch
  by Xiang Zhang.

* bpo-27581: Don’t rely on wrapping for overflow check in
  PySequence_Tuple().  Patch by Xiang Zhang.

* bpo-1621: Avoid signed integer overflow in list and tuple
  operations. Patch by Xiang Zhang.

* bpo-27419: Standard __import__() no longer look up “__import__” in
  globals or builtins for importing submodules or “from import”.
  Fixed a crash if raise a warning about unabling to resolve package
  from __spec__ or __package__.

* bpo-27083: Respect the PYTHONCASEOK environment variable under
  Windows.

* bpo-27514: Make having too many statically nested blocks a
  SyntaxError instead of SystemError.

* bpo-27366: Implemented **PEP 487** (Simpler customization of class
  creation). Upon subclassing, the __init_subclass__ classmethod is
  called on the base class. Descriptors are initialized with
  __set_name__ after class creation.


Library
-------

* bpo-26027: Add **PEP 519**/__fspath__() support to the os and
  os.path modules. Includes code from Jelle Zijlstra. (See also:
  bpo-27524)

* bpo-27598: Add Collections to collections.abc. Patch by Ivan
  Levkivskyi, docs by Neil Girdhar.

* bpo-25958: Support “anti-registration” of special methods from
  various ABCs, like __hash__, __iter__ or __len__.  All these (and
  several more) can be set to None in an implementation class and the
  behavior will be as if the method is not defined at all.
  (Previously, this mechanism existed only for __hash__, to make
  mutable classes unhashable.)  Code contributed by Andrew Barnert and
  Ivan Levkivskyi.

* bpo-16764: Support keyword arguments to zlib.decompress().  Patch by
  Xiang Zhang.

* bpo-27736: Prevent segfault after interpreter re-initialization due
  to ref count problem introduced in code for bpo-27038 in 3.6.0a3.
  Patch by Xiang Zhang.

* bpo-25628: The *verbose* and *rename* parameters for
  collections.namedtuple are now keyword-only.

* bpo-12345: Add mathematical constant tau to math and cmath. See also
  **PEP 628**.

* bpo-26823: traceback.StackSummary.format now abbreviates large
  sections of repeated lines as “[Previous line repeated {count} more
  times]” (this change then further affects other traceback display
  operations in the module). Patch by Emanuel Barry.

* bpo-27664: Add to concurrent.futures.thread.ThreadPoolExecutor() the
  ability to specify a thread name prefix.

* bpo-27181: Add geometric_mean and harmonic_mean to statistics
  module.

* bpo-27573: code.interact now prints an message when exiting.

* bpo-6422: Add autorange method to timeit.Timer objects.

* bpo-27773: Correct some memory management errors server_hostname in
  _ssl.wrap_socket().

* bpo-26750: unittest.mock.create_autospec() now works properly for
  subclasses of property() and other data descriptors.  Removes the
  never publicly used, never documented unittest.mock.DescriptorTypes
  tuple.

* bpo-26754: Undocumented support of general bytes-like objects as
  path in compile() and similar functions is now deprecated.

* bpo-26800: Undocumented support of general bytes-like objects as
  paths in os functions is now deprecated.

* bpo-26981: Add _order_ compatibility shim to enum.Enum for Python
  2/3 code bases.

* bpo-27661: Added tzinfo keyword argument to datetime.combine.

* In the curses module, raise an error if window.getstr() or
  window.instr() is passed a negative value.

* bpo-27783: Fix possible usage of uninitialized memory in
  operator.methodcaller.

* bpo-27774: Fix possible Py_DECREF on unowned object in _sre.

* bpo-27760: Fix possible integer overflow in binascii.b2a_qp.

* bpo-27758: Fix possible integer overflow in the _csv module for
  large record lengths.

* bpo-27568: Prevent HTTPoxy attack (CVE-2016-1000110). Ignore the
  HTTP_PROXY variable when REQUEST_METHOD environment is set, which
  indicates that the script is in CGI mode.

* bpo-7063: Remove dead code from the “array” module’s slice handling.
  Patch by Chuck.

* bpo-27656: Do not assume sched.h defines any SCHED_* constants.

* bpo-27130: In the “zlib” module, fix handling of large buffers
  (typically 4 GiB) when compressing and decompressing.  Previously,
  inputs were limited to 4 GiB, and compression and decompression
  operations did not properly handle results of 4 GiB.

* bpo-24773: Implemented **PEP 495** (Local Time Disambiguation).

* Expose the EPOLLEXCLUSIVE constant (when it is defined) in the
  select module.

* bpo-27567: Expose the EPOLLRDHUP and POLLRDHUP constants in the
  select module.

* bpo-1621: Avoid signed int negation overflow in the “audioop”
  module.

* bpo-27533: Release GIL in nt._isdir

* bpo-17711: Fixed unpickling by the persistent ID with protocol 0.
  Original patch by Alexandre Vassalotti.

* bpo-27522: Avoid an unintentional reference cycle in
  email.feedparser.

* bpo-27512: Fix a segfault when os.fspath() called an __fspath__()
  method that raised an exception. Patch by Xiang Zhang.


IDLE
----

* bpo-27714: text_textview and test_autocomplete now pass when re-run
  in the same process.  This occurs when test_idle fails when run with
  the -w option but without -jn.  Fix warning from test_config.

* bpo-27621: Put query response validation error messages in the query
  box itself instead of in a separate messagebox.  Redo tests to
  match. Add Mac OSX refinements. Original patch by Mark Roseman.

* bpo-27620: Escape key now closes Query box as cancelled.

* bpo-27609: IDLE: tab after initial whitespace should tab, not
  autocomplete. This fixes problem with writing docstrings at least
  twice indented.

* bpo-27609: Explicitly return None when there are also non-None
  returns. In a few cases, reverse a condition and eliminate a return.

* bpo-25507: IDLE no longer runs buggy code because of its tkinter
  imports. Users must include the same imports required to run
  directly in Python.

* bpo-27173: Add ‘IDLE Modern Unix’ to the built-in key sets. Make the
  default key set depend on the platform. Add tests for the changes to
  the config module.

* bpo-27452: add line counter and crc to IDLE configHandler test dump.


Tests
-----

* bpo-25805: Skip a test in test_pkgutil as needed that doesn’t work
  when "__name__ == __main__". Patch by SilentGhost.

* bpo-27472: Add test.support.unix_shell as the path to the default
  shell.

* bpo-27369: In test_pyexpat, avoid testing an error message detail
  that changed in Expat 2.2.0.

* bpo-27594: Prevent assertion error when running test_ast with
  coverage enabled: ensure code object has a valid first line number.
  Patch suggested by Ivan Levkivskyi.


Windows
-------

* bpo-27647: Update bundled Tcl/Tk to 8.6.6.

* bpo-27610: Adds **PEP 514** metadata to Windows installer

* bpo-27469: Adds a shell extension to the launcher so that drag and
  drop works correctly.

* bpo-27309: Enables proper Windows styles in python[w].exe manifest.


Build
-----

* bpo-27713: Suppress spurious build warnings when updating
  importlib’s bootstrap files. Patch by Xiang Zhang

* bpo-25825: Correct the references to Modules/python.exp, which is
  required on AIX.  The references were accidentally changed in
  3.5.0a1.

* bpo-27453: CPP invocation in configure must use CPPFLAGS. Patch by
  Chi Hsuan Yen.

* bpo-27641: The configure script now inserts comments into the
  makefile to prevent the pgen and _freeze_importlib executables from
  being cross-compiled.

* bpo-26662: Set PYTHON_FOR_GEN in configure as the Python program to
  be used for file generation during the build.

* bpo-10910: Avoid C++ compilation errors on FreeBSD and OS X. Also
  update FreedBSD version checks for the original ctype UTF-8
  workaround.


Python 3.6.0 alpha 3
====================

*Release date: 2016-07-11*


Security
--------

* bpo-27278: Fix os.urandom() implementation using getrandom() on
  Linux. Truncate size to INT_MAX and loop until we collected enough
  random bytes, instead of casting a directly Py_ssize_t to int.

* bpo-22636: Avoid shell injection problems with
  ctypes.util.find_library().


Core and Builtins
-----------------

* bpo-27473: Fixed possible integer overflow in bytes and bytearray
  concatenations. Patch by Xiang Zhang.

* bpo-23034: The output of a special Python build with defined
  COUNT_ALLOCS, SHOW_ALLOC_COUNT or SHOW_TRACK_COUNT macros is now off
  by  default.  It can be re-enabled using the “-X showalloccount”
  option.  It now outputs to stderr instead of stdout.

* bpo-27443: __length_hint__() of bytearray iterators no longer return
  a negative integer for a resized bytearray.

* bpo-27007: The fromhex() class methods of bytes and bytearray
  subclasses now return an instance of corresponding subclass.


Library
-------

* bpo-26844: Fix error message for imp.find_module() to refer to
  ‘path’ instead of ‘name’. Patch by Lev Maximov.

* bpo-23804: Fix SSL zero-length recv() calls to not block and not
  raise an error about unclean EOF.

* bpo-27466: Change time format returned by http.cookie.time2netscape,
  confirming the netscape cookie format and making it consistent with
  documentation.

* bpo-21708: Deprecated dbm.dumb behavior that differs from common dbm
  behavior: creating a database in ‘r’ and ‘w’ modes and modifying a
  database in ‘r’ mode.

* bpo-26721: Change the socketserver.StreamRequestHandler.wfile
  attribute to implement BufferedIOBase. In particular, the write()
  method no longer does partial writes.

* bpo-22115: Added methods trace_add, trace_remove and trace_info in
  the tkinter.Variable class.  They replace old methods
  trace_variable, trace, trace_vdelete and trace_vinfo that use
  obsolete Tcl commands and might not work in future versions of Tcl.
  Fixed old tracing methods: trace_vdelete() with wrong mode no longer
  break tracing, trace_vinfo() now always returns a list of pairs of
  strings, tracing in the “u” mode now works.

* bpo-26243: Only the level argument to zlib.compress() is keyword
  argument now.  The first argument is positional-only.

* bpo-27038: Expose the DirEntry type as os.DirEntry. Code patch by
  Jelle Zijlstra.

* bpo-27186: Update os.fspath()/PyOS_FSPath() to check the return
  value of __fspath__() to be either str or bytes.

* bpo-18726: All optional parameters of the dump(), dumps(), load()
  and loads() functions and JSONEncoder and JSONDecoder class
  constructors in the json module are now keyword-only.

* bpo-27319: Methods selection_set(), selection_add(),
  selection_remove() and selection_toggle() of ttk.TreeView now allow
  passing multiple items as multiple arguments instead of passing them
  as a tuple.  Deprecated undocumented ability of calling the
  selection() method with arguments.

* bpo-27079: Fixed curses.ascii functions isblank(), iscntrl() and
  ispunct().

* bpo-27294: Numerical state in the repr for Tkinter event objects is
  now represented as a combination of known flags.

* bpo-27177: Match objects in the re module now support index-like
  objects as group indices.  Based on patches by Jeroen Demeyer and
  Xiang Zhang.

* bpo-26754: Some functions (compile() etc) accepted a filename
  argument encoded as an iterable of integers. Now only strings and
  byte-like objects are accepted.

* bpo-26536: socket.ioctl now supports SIO_LOOPBACK_FAST_PATH. Patch
  by Daniel Stokes.

* bpo-27048: Prevents distutils failing on Windows when environment
  variables contain non-ASCII characters

* bpo-27330: Fixed possible leaks in the ctypes module.

* bpo-27238: Got rid of bare excepts in the turtle module.  Original
  patch by Jelle Zijlstra.

* bpo-27122: When an exception is raised within the context being
  managed by a contextlib.ExitStack() and one of the exit stack
  generators catches and raises it in a chain, do not re-raise the
  original exception when exiting, let the new chained one through.
  This avoids the **PEP 479** bug described in issue25782.

* bpo-16864: sqlite3.Cursor.lastrowid now supports REPLACE statement.
  Initial patch by Alex LordThorsen.

* bpo-26386: Fixed ttk.TreeView selection operations with item id’s
  containing spaces.

* bpo-8637: Honor a pager set by the env var MANPAGER (in preference
  to one set by the env var PAGER).

* bpo-16182: Fix various functions in the “readline” module to use the
  locale encoding, and fix get_begidx() and get_endidx() to return
  code point indexes.

* bpo-27392: Add loop.connect_accepted_socket(). Patch by Jim Fulton.


IDLE
----

* bpo-27477: IDLE search dialogs now use ttk widgets.

* bpo-27173: Add ‘IDLE Modern Unix’ to the built-in key sets. Make the
  default key set depend on the platform. Add tests for the changes to
  the config module.

* bpo-27452: make command line “idle-test> python test_help.py” work.
  __file__ is relative when python is started in the file’s directory.

* bpo-27452: add line counter and crc to IDLE configHandler test dump.

* bpo-27380: IDLE: add query.py with base Query dialog and ttk
  widgets. Module had subclasses SectionName, ModuleName, and
  HelpSource, which are used to get information from users by
  configdialog and file =>Load Module. Each subclass has itw own
  validity checks.  Using ModuleName allows users to edit bad module
  names instead of starting over. Add tests and delete the two files
  combined into the new one.

* bpo-27372: Test_idle no longer changes the locale.

* bpo-27365: Allow non-ascii chars in IDLE NEWS.txt, for contributor
  names.

* bpo-27245: IDLE: Cleanly delete custom themes and key bindings.
  Previously, when IDLE was started from a console or by import, a
  cascade of warnings was emitted. Patch by Serhiy Storchaka.

* bpo-24137: Run IDLE, test_idle, and htest with tkinter default root
  disabled.  Fix code and tests that fail with this restriction.  Fix
  htests to not create a second and redundant root and mainloop.

* bpo-27310: Fix IDLE.app failure to launch on OS X due to vestigial
  import.


C API
-----

* bpo-26754: PyUnicode_FSDecoder() accepted a filename argument
  encoded as an iterable of integers. Now only strings and byte-like
  objects are accepted.


Build
-----

* bpo-28066: Fix the logic that searches build directories for
  generated include files when building outside the source tree.

* bpo-27442: Expose the Android API level that python was built
  against, in sysconfig.get_config_vars() as ‘ANDROID_API_LEVEL’.

* bpo-27434: The interpreter that runs the cross-build, found in PATH,
  must now be of the same feature version (e.g. 3.6) as the source
  being built.

* bpo-26930: Update Windows builds to use OpenSSL 1.0.2h.

* bpo-23968: Rename the platform directory from plat-$(MACHDEP) to
  plat-$(PLATFORM_TRIPLET). Rename the config directory (LIBPL) from
  config-$(LDVERSION) to config-$(LDVERSION)-$(PLATFORM_TRIPLET).
  Install the platform specific _sysconfigdata module into the
  platform directory and rename it to include the ABIFLAGS.

* Don’t use largefile support for GNU/Hurd.


Tools/Demos
-----------

* bpo-27332: Fixed the type of the first argument of module-level
  functions generated by Argument Clinic.  Patch by Petr Viktorin.

* bpo-27418: Fixed Tools/importbench/importbench.py.


Documentation
-------------

* bpo-19489: Moved the search box from the sidebar to the header and
  footer of each page. Patch by Ammar Askar.

* bpo-27285: Update documentation to reflect the deprecation of
  "pyvenv" and normalize on the term “virtual environment”. Patch by
  Steve Piercy.


Tests
-----

* bpo-27027: Added test.support.is_android that is True when this is
  an Android build.


Python 3.6.0 alpha 2
====================

*Release date: 2016-06-13*


Security
--------

* bpo-26556: Update expat to 2.1.1, fixes CVE-2015-1283.

* Fix TLS stripping vulnerability in smtplib, CVE-2016-0772. Reported
  by Team Oststrom.

* bpo-26839: On Linux, "os.urandom()" now calls "getrandom()" with
  "GRND_NONBLOCK" to fall back on reading "/dev/urandom" if the
  urandom entropy pool is not initialized yet. Patch written by Colm
  Buckley.


Core and Builtins
-----------------

* bpo-27095: Simplified MAKE_FUNCTION and removed MAKE_CLOSURE
  opcodes. Patch by Demur Rumed.

* bpo-27190: Raise NotSupportedError if sqlite3 is older than 3.3.1.
  Patch by Dave Sawyer.

* bpo-27286: Fixed compiling BUILD_MAP_UNPACK_WITH_CALL opcode.
  Calling function with generalized unpacking (PEP 448) and
  conflicting keyword names could cause undefined behavior.

* bpo-27140: Added BUILD_CONST_KEY_MAP opcode.

* bpo-27186: Add support for os.PathLike objects to open() (part of
  **PEP 519**).

* bpo-27066: Fixed SystemError if a custom opener (for open()) returns
  a negative number without setting an exception.

* bpo-26983: float() now always return an instance of exact float. The
  deprecation warning is emitted if __float__ returns an instance of a
  strict subclass of float.  In a future versions of Python this can
  be an error.

* bpo-27097: Python interpreter is now about 7% faster due to
  optimized instruction decoding.  Based on patch by Demur Rumed.

* bpo-26647: Python interpreter now uses 16-bit wordcode instead of
  bytecode. Patch by Demur Rumed.

* bpo-23275: Allow assigning to an empty target list in round
  brackets: () = iterable.

* bpo-27243: Update the __aiter__ protocol: instead of returning an
  awaitable that resolves to an asynchronous iterator, the
  asynchronous iterator should be returned directly.  Doing the former
  will trigger a PendingDeprecationWarning.


Library
-------

* Comment out socket (SO_REUSEPORT) and posix (O_SHLOCK, O_EXLOCK)
  constants exposed on the API which are not implemented on GNU/Hurd.
  They would not work at runtime anyway.

* bpo-27025: Generated names for Tkinter widgets are now more
  meaningful and recognizable.

* bpo-25455: Fixed crashes in repr of recursive ElementTree.Element
  and functools.partial objects.

* bpo-27294: Improved repr for Tkinter event objects.

* bpo-20508: Improve exception message of IPv{4,6}Network.__getitem__.
  Patch by Gareth Rees.

* bpo-21386: Implement missing IPv4Address.is_global property.  It was
  documented since 07a5610bae9d.  Initial patch by Roger Luethi.

* bpo-27029: Removed deprecated support of universal newlines mode
  from ZipFile.open().

* bpo-27030: Unknown escapes consisting of "'\'" and an ASCII letter
  in regular expressions now are errors.  The re.LOCALE flag now can
  be used only with bytes patterns.

* bpo-27186: Add os.PathLike support to DirEntry (part of **PEP
  519**). Initial patch by Jelle Zijlstra.

* bpo-20900: distutils register command now decodes HTTP responses
  correctly.  Initial patch by ingrid.

* bpo-27186: Add os.PathLike support to pathlib, removing its
  provisional status (part of PEP 519). Initial patch by Dusty
  Phillips.

* bpo-27186: Add support for os.PathLike objects to os.fsencode() and
  os.fsdecode() (part of **PEP 519**).

* bpo-27186: Introduce os.PathLike and os.fspath() (part of **PEP
  519**).

* A new version of typing.py provides several new classes and
  features: @overload outside stubs, Reversible, DefaultDict, Text,
  ContextManager, Type[], NewType(), TYPE_CHECKING, and numerous bug
  fixes (note that some of the new features are not yet implemented in
  mypy or other static analyzers). Also classes for **PEP 492**
  (Awaitable, AsyncIterable, AsyncIterator) have been added (in fact
  they made it into 3.5.1 but were never mentioned).

* bpo-25738: Stop http.server.BaseHTTPRequestHandler.send_error() from
  sending a message body for 205 Reset Content.  Also, don’t send
  Content header fields in responses that don’t have a body.  Patch by
  Susumu Koshiba.

* bpo-21313: Fix the “platform” module to tolerate when sys.version
  contains truncated build information.

* bpo-23883: Added missing APIs to __all__ to match the documented
  APIs for the following modules: cgi, mailbox, mimetypes, plistlib
  and smtpd. Patches by Jacek Kołodziej.

* bpo-27164: In the zlib module, allow decompressing raw Deflate
  streams with a predefined zdict.  Based on patch by Xiang Zhang.

* bpo-24291: Fix wsgiref.simple_server.WSGIRequestHandler to
  completely write data to the client.  Previously it could do partial
  writes and truncate data.  Also, wsgiref.handler.ServerHandler can
  now handle stdout doing partial writes, but this is deprecated.

* bpo-21272: Use _sysconfigdata.py to initialize distutils.sysconfig.

* bpo-19611: "inspect" now reports the implicit ".0" parameters
  generated by the compiler for comprehension and generator expression
  scopes as if they were positional-only parameters called
  "implicit0". Patch by Jelle Zijlstra.

* bpo-26809: Add "__all__" to "string".  Patch by Emanuel Barry.

* bpo-26373: subprocess.Popen.communicate now correctly ignores
  BrokenPipeError when the child process dies before .communicate() is
  called in more/all circumstances.

* signal, socket, and ssl module IntEnum constant name lookups now
  return a consistent name for values having multiple names.  Ex:
  signal.Signals(6) now refers to itself as signal.SIGALRM rather than
  flipping between that and signal.SIGIOT based on the interpreter’s
  hash randomization seed.

* bpo-27167: Clarify the subprocess.CalledProcessError error message
  text when the child process died due to a signal.

* bpo-25931: Don’t define socketserver.Forking* names on platforms
  such as Windows that do not support os.fork().

* bpo-21776: distutils.upload now correctly handles HTTPError. Initial
  patch by Claudiu Popa.

* bpo-26526: Replace custom parse tree validation in the parser module
  with a simple DFA validator.

* bpo-27114: Fix SSLContext._load_windows_store_certs fails with
  PermissionError

* bpo-18383: Avoid creating duplicate filters when using
  filterwarnings and simplefilter. Based on patch by Alex Shkop.

* bpo-23026: winreg.QueryValueEx() now return an integer for REG_QWORD
  type.

* bpo-26741: subprocess.Popen destructor now emits a ResourceWarning
  warning if the child process is still running.

* bpo-27056: Optimize pickle.load() and pickle.loads(), up to 10%
  faster to deserialize a lot of small objects.

* bpo-21271: New keyword only parameters in reset_mock call.


IDLE
----

* bpo-5124: Paste with text selected now replaces the selection on
  X11. This matches how paste works on Windows, Mac, most modern Linux
  apps, and ttk widgets. Original patch by Serhiy Storchaka.

* bpo-24750: Switch all scrollbars in IDLE to ttk versions. Where
  needed, minimal tests are added to cover changes.

* bpo-24759: IDLE requires tk 8.5 and availability ttk widgets. Delete
  now unneeded tk version tests and code for older versions. Add test
  for IDLE syntax colorizer.

* bpo-27239: idlelib.macosx.isXyzTk functions initialize as needed.

* bpo-27262: move Aqua unbinding code, which enable context menus, to
  macosx.

* bpo-24759: Make clear in idlelib.idle_test.__init__ that the
  directory is a private implementation of test.test_idle and tool for
  maintainers.

* bpo-27196: Stop ‘ThemeChanged’ warnings when running IDLE tests.
  These persisted after other warnings were suppressed in #20567.
  Apply Serhiy Storchaka’s update_idletasks solution to four test
  files. Record this additional advice in idle_test/README.txt

* bpo-20567: Revise idle_test/README.txt with advice about avoiding tk
  warning messages from tests.  Apply advice to several IDLE tests.

* bpo-24225: Update idlelib/README.txt with new file names and event
  handlers.

* bpo-27156: Remove obsolete code not used by IDLE.

* bpo-27117: Make colorizer htest and turtledemo work with dark
  themes. Move code for configuring text widget colors to a new
  function.

* bpo-24225: Rename many "idlelib/*.py" and "idle_test/test_*.py"
  files. Edit files to replace old names with new names when the old
  name referred to the module rather than the class it contained. See
  the issue and IDLE section in What’s New in 3.6 for more.

* bpo-26673: When tk reports font size as 0, change to size 10. Such
  fonts on Linux prevented the configuration dialog from opening.

* bpo-21939: Add test for IDLE’s percolator. Original patch by
  Saimadhav Heblikar.

* bpo-21676: Add test for IDLE’s replace dialog. Original patch by
  Saimadhav Heblikar.

* bpo-18410: Add test for IDLE’s search dialog. Original patch by
  Westley Martínez.

* bpo-21703: Add test for undo delegator.  Patch mostly by Saimadhav
  Heblikar .

* bpo-27044: Add ConfigDialog.remove_var_callbacks to stop memory
  leaks.

* bpo-23977: Add more asserts to test_delegator.


Documentation
-------------

* bpo-16484: Change the default PYTHONDOCS URL to “https:”, and fix
  the resulting links to use lowercase.  Patch by Sean Rodman, test by
  Kaushik Nadikuditi.

* bpo-24136: Document the new **PEP 448** unpacking syntax of 3.5.

* bpo-22558: Add remaining doc links to source code for Python-coded
  modules. Patch by Yoni Lavi.


Tests
-----

* bpo-25285: regrtest now uses subprocesses when the -j1 command line
  option is used: each test file runs in a fresh child process.
  Before, the -j1 option was ignored.

* bpo-25285: Tools/buildbot/test.bat script now uses -j1 by default to
  run each test file in fresh child process.


Windows
-------

* bpo-27064: The py.exe launcher now defaults to Python 3. The Windows
  launcher "py.exe" no longer prefers an installed Python 2 version
  over Python 3 by default when used interactively.

* bpo-17500: Remove unused and outdated icons. (See also:
  https://github.com/python/pythondotorg/issues/945)


Build
-----

* bpo-27229: Fix the cross-compiling pgen rule for in-tree builds.
  Patch by Xavier de Gaye.

* bpo-26930: Update OS X 10.5+ 32-bit-only installer to build and link
  with OpenSSL 1.0.2h.


C API
-----

* bpo-27186: Add the PyOS_FSPath() function (part of **PEP 519**).

* bpo-26282: PyArg_ParseTupleAndKeywords() now supports positional-
  only parameters.


Tools/Demos
-----------

* bpo-26282: Argument Clinic now supports positional-only and keyword
  parameters in the same function.


Python 3.6.0 alpha 1
====================

*Release date: 2016-05-16*


Security
--------

* bpo-26657: Fix directory traversal vulnerability with http.server on
  Windows.  This fixes a regression that was introduced in 3.3.4rc1
  and 3.4.0rc1.  Based on patch by Philipp Hagemeister.

* bpo-26313: ssl.py _load_windows_store_certs fails if windows cert
  store is empty. Patch by Baji.

* bpo-25939: On Windows open the cert store readonly in
  ssl.enum_certificates.


Core and Builtins
-----------------

* bpo-20041: Fixed TypeError when frame.f_trace is set to None. Patch
  by Xavier de Gaye.

* bpo-26168: Fixed possible refleaks in failing Py_BuildValue() with
  the “N” format unit.

* bpo-26991: Fix possible refleak when creating a function with
  annotations.

* bpo-27039: Fixed bytearray.remove() for values greater than 127.
  Based on patch by Joe Jevnik.

* bpo-23640: int.from_bytes() no longer bypasses constructors for
  subclasses.

* bpo-27005: Optimized the float.fromhex() class method for exact
  float. It is now 2 times faster.

* bpo-18531: Single var-keyword argument of dict subtype was passed
  unscathed to the C-defined function.  Now it is converted to exact
  dict.

* bpo-26811: gc.get_objects() no longer contains a broken tuple with
  NULL pointer.

* bpo-20120: Use RawConfigParser for .pypirc parsing, removing support
  for interpolation unintentionally added with move to Python 3.
  Behavior no longer does any interpolation in .pypirc files, matching
  behavior in Python 2.7 and Setuptools 19.0.

* bpo-26249: Memory functions of the "PyMem_Malloc()" domain
  ("PYMEM_DOMAIN_MEM") now use the pymalloc allocator rather than
  system "malloc()". Applications calling "PyMem_Malloc()" without
  holding the GIL can now crash: use "PYTHONMALLOC=debug" environment
  variable to validate the usage of memory allocators in your
  application.

* bpo-26802: Optimize function calls only using unpacking like
  "func(*tuple)" (no other positional argument, no keyword): avoid
  copying the tuple. Patch written by Joe Jevnik.

* bpo-26659: Make the builtin slice type support cycle collection.

* bpo-26718: super.__init__ no longer leaks memory if called multiple
  times. NOTE: A direct call of super.__init__ is not endorsed!

* bpo-27138: Fix the doc comment for FileFinder.find_spec().

* bpo-27147: Mention **PEP 420** in the importlib docs.

* bpo-25339: PYTHONIOENCODING now has priority over locale in setting
  the error handler for stdin and stdout.

* bpo-26494: Fixed crash on iterating exhausting iterators. Affected
  classes are generic sequence iterators, iterators of str, bytes,
  bytearray, list, tuple, set, frozenset, dict, OrderedDict,
  corresponding views and os.scandir() iterator.

* bpo-26574: Optimize "bytes.replace(b'', b'.')" and
  "bytearray.replace(b'', b'.')". Patch written by Josh Snider.

* bpo-26581: If coding cookie is specified multiple times on a line in
  Python source code file, only the first one is taken to account.

* bpo-19711: Add tests for reloading namespace packages.

* bpo-21099: Switch applicable importlib tests to use **PEP 451** API.

* bpo-26563: Debug hooks on Python memory allocators now raise a fatal
  error if functions of the "PyMem_Malloc()" family are called without
  holding the GIL.

* bpo-26564: On error, the debug hooks on Python memory allocators now
  use the "tracemalloc" module to get the traceback where a memory
  block was allocated.

* bpo-26558: The debug hooks on Python memory allocator
  "PyObject_Malloc()" now detect when functions are called without
  holding the GIL.

* bpo-26516: Add "PYTHONMALLOC" environment variable to set the Python
  memory allocators and/or install debug hooks.

* bpo-26516: The "PyMem_SetupDebugHooks()" function can now also be
  used on Python compiled in release mode.

* bpo-26516: The "PYTHONMALLOCSTATS" environment variable can now also
  be used on Python compiled in release mode. It now has no effect if
  set to an empty string.

* bpo-26516: In debug mode, debug hooks are now also installed on
  Python memory allocators when Python is configured without pymalloc.

* bpo-26464: Fix str.translate() when string is ASCII and first
  replacements removes character, but next replacement uses a non-
  ASCII character or a string longer than 1 character. Regression
  introduced in Python 3.5.0.

* bpo-22836: Ensure exception reports from PyErr_Display() and
  PyErr_WriteUnraisable() are sensible even when formatting them
  produces secondary errors.  This affects the reports produced by
  sys.__excepthook__() and when __del__() raises an exception.

* bpo-26302: Correct behavior to reject comma as a legal character for
  cookie names.

* bpo-26136: Upgrade the warning when a generator raises StopIteration
  from PendingDeprecationWarning to DeprecationWarning.  Patch by
  Anish Shah.

* bpo-26204: The compiler now ignores all constant statements: bytes,
  str, int, float, complex, name constants (None, False, True),
  Ellipsis and ast.Constant; not only str and int. For example, "1.0"
  is now ignored in "def f(): 1.0".

* bpo-4806: Avoid masking the original TypeError exception when using
  star ("*") unpacking in function calls.  Based on patch by Hagen
  Fürstenau and Daniel Urban.

* bpo-26146: Add a new kind of AST node: "ast.Constant". It can be
  used by external AST optimizers, but the compiler does not emit
  directly such node.

* bpo-23601: Sped-up allocation of dict key objects by using Python’s
  small object allocator.  (Contributed by Julian Taylor.)

* bpo-18018: Import raises ImportError instead of SystemError if a
  relative import is attempted without a known parent package.

* bpo-25843: When compiling code, don’t merge constants if they are
  equal but have a different types. For example, "f1, f2 = lambda: 1,
  lambda: 1.0" is now correctly compiled to two different functions:
  "f1()" returns "1" ("int") and "f2()" returns "1.0" ("float"), even
  if "1" and "1.0" are equal.

* bpo-26107: The format of the "co_lnotab" attribute of code objects
  changes to support negative line number delta.

* bpo-26154: Add a new private _PyThreadState_UncheckedGet() function
  to get the current Python thread state, but don’t issue a fatal
  error if it is NULL. This new function must be used instead of
  accessing directly the _PyThreadState_Current variable.  The
  variable is no more exposed since Python 3.5.1 to hide the exact
  implementation of atomic C types, to avoid compiler issues.

* bpo-25791: If __package__ != __spec__.parent or if neither
  __package__ or __spec__ are defined then ImportWarning is raised.

* bpo-22995: [UPDATE] Comment out the one of the pickleability tests
  in _PyObject_GetState() due to regressions observed in Cython-based
  projects.

* bpo-25961: Disallowed null characters in the type name.

* bpo-25973: Fix segfault when an invalid nonlocal statement binds a
  name starting with two underscores.

* bpo-22995: Instances of extension types with a state that aren’t
  subclasses of list or dict and haven’t implemented any pickle-
  related methods (__reduce__, __reduce_ex__, __getnewargs__,
  __getnewargs_ex__, or __getstate__), can no longer be pickled.
  Including memoryview.

* bpo-20440: Massive replacing unsafe attribute setting code with
  special macro Py_SETREF.

* bpo-25766: Special method __bytes__() now works in str subclasses.

* bpo-25421: __sizeof__ methods of builtin types now use dynamic basic
  size. This allows sys.getsize() to work correctly with their
  subclasses with __slots__ defined.

* bpo-25709: Fixed problem with in-place string concatenation and
  utf-8 cache.

* bpo-5319: New Py_FinalizeEx() API allowing Python to set an exit
  status of 120 on failure to flush buffered streams.

* bpo-25485: telnetlib.Telnet is now a context manager.

* bpo-24097: Fixed crash in object.__reduce__() if slot name is freed
  inside __getattr__.

* bpo-24731: Fixed crash on converting objects with special methods
  __bytes__, __trunc__, and __float__ returning instances of
  subclasses of bytes, int, and float to subclasses of bytes, int, and
  float correspondingly.

* bpo-25630: Fix a possible segfault during argument parsing in
  functions that accept filesystem paths.

* bpo-23564: Fixed a partially broken sanity check in the
  _posixsubprocess internals regarding how fds_to_pass were passed to
  the child.  The bug had no actual impact as subprocess.py already
  avoided it.

* bpo-25388: Fixed tokenizer crash when processing undecodable source
  code with a null byte.

* bpo-25462: The hash of the key now is calculated only once in most
  operations in C implementation of OrderedDict.

* bpo-22995: Default implementation of __reduce__ and __reduce_ex__
  now rejects builtin types with not defined __new__.

* bpo-24802: Avoid buffer overreads when int(), float(), compile(),
  exec() and eval() are passed bytes-like objects.  These objects are
  not necessarily terminated by a null byte, but the functions assumed
  they were.

* bpo-25555: Fix parser and AST: fill lineno and col_offset of “arg”
  node when compiling AST from Python objects.

* bpo-24726: Fixed a crash and leaking NULL in repr() of OrderedDict
  that was mutated by direct calls of dict methods.

* bpo-25449: Iterating OrderedDict with keys with unstable hash now
  raises KeyError in C implementations as well as in Python
  implementation.

* bpo-25395: Fixed crash when highly nested OrderedDict structures
  were garbage collected.

* bpo-25401: Optimize bytes.fromhex() and bytearray.fromhex(): they
  are now between 2x and 3.5x faster.

* bpo-25399: Optimize bytearray % args using the new private
  _PyBytesWriter API. Formatting is now between 2.5 and 5 times
  faster.

* bpo-25274: sys.setrecursionlimit() now raises a RecursionError if
  the new recursion limit is too low depending at the current
  recursion depth. Modify also the “lower-water mark” formula to make
  it monotonic. This mark is used to decide when the overflowed flag
  of the thread state is reset.

* bpo-24402: Fix input() to prompt to the redirected stdout when
  sys.stdout.fileno() fails.

* bpo-25349: Optimize bytes % args using the new private
  _PyBytesWriter API. Formatting is now up to 2 times faster.

* bpo-24806: Prevent builtin types that are not allowed to be
  subclassed from being subclassed through multiple inheritance.

* bpo-25301: The UTF-8 decoder is now up to 15 times as fast for error
  handlers: "ignore", "replace" and "surrogateescape".

* bpo-24848: Fixed a number of bugs in UTF-7 decoding of misformed
  data.

* bpo-25267: The UTF-8 encoder is now up to 75 times as fast for error
  handlers: "ignore", "replace", "surrogateescape", "surrogatepass".
  Patch co-written with Serhiy Storchaka.

* bpo-25280: Import trace messages emitted in verbose (-v) mode are no
  longer formatted twice.

* bpo-25227: Optimize ASCII and latin1 encoders with the
  "surrogateescape" error handler: the encoders are now up to 3 times
  as fast. Initial patch written by Serhiy Storchaka.

* bpo-25003: On Solaris 11.3 or newer, os.urandom() now uses the
  getrandom() function instead of the getentropy() function. The
  getentropy() function is blocking to generate very good quality
  entropy, os.urandom() doesn’t need such high-quality entropy.

* bpo-9232: Modify Python’s grammar to allow trailing commas in the
  argument list of a function declaration.  For example, “def f(*, a =
  3,): pass” is now legal. Patch from Mark Dickinson.

* bpo-24965: Implement **PEP 498** “Literal String Interpolation”.
  This allows you to embed expressions inside f-strings, which are
  converted to normal strings at run time. Given x=3, then
  f’value={x}’ == ‘value=3’. Patch by Eric V. Smith.

* bpo-26478: Fix semantic bugs when using binary operators with
  dictionary views and tuples.

* bpo-26171: Fix possible integer overflow and heap corruption in
  zipimporter.get_data().

* bpo-25660: Fix TAB key behaviour in REPL with readline.

* bpo-26288: Optimize PyLong_AsDouble.

* bpo-26289: Optimize floor and modulo division for single-digit
  longs. Microbenchmarks show 2-2.5x improvement.  Built-in ‘divmod’
  function is now also ~10% faster. (See also: bpo-26315)

* bpo-25887: Raise a RuntimeError when a coroutine object is awaited
  more than once.


Library
-------

* bpo-27057: Fix os.set_inheritable() on Android, ioctl() is blocked
  by SELinux and fails with EACCESS. The function now falls back to
  fcntl(). Patch written by Michał Bednarski.

* bpo-27014: Fix infinite recursion using typing.py.  Thanks to Kalle
  Tuure!

* bpo-27031: Removed dummy methods in Tkinter widget classes:
  tk_menuBar() and tk_bindForTraversal().

* bpo-14132: Fix urllib.request redirect handling when the target only
  has a query string.  Original fix by Ján Janech.

* bpo-17214: The “urllib.request” module now percent-encodes non-ASCII
  bytes found in redirect target URLs.  Some servers send Location
  header fields with non-ASCII bytes, but “http.client” requires the
  request target to be ASCII-encodable, otherwise a UnicodeEncodeError
  is raised.  Based on patch by Christian Heimes.

* bpo-27033: The default value of the decode_data parameter for
  smtpd.SMTPChannel and smtpd.SMTPServer constructors is changed to
  False.

* bpo-27034: Removed deprecated class asynchat.fifo.

* bpo-26870: Added readline.set_auto_history(), which can stop entries
  being automatically added to the history list.  Based on patch by
  Tyler Crompton.

* bpo-26039: zipfile.ZipFile.open() can now be used to write data into
  a ZIP file, as well as for extracting data.  Patch by Thomas
  Kluyver.

* bpo-26892: Honor debuglevel flag in urllib.request.HTTPHandler.
  Patch contributed by Chi Hsuan Yen.

* bpo-22274: In the subprocess module, allow stderr to be redirected
  to stdout even when stdout is not redirected.  Patch by Akira Li.

* bpo-26807: mock_open ‘files’ no longer error on readline at end of
  file. Patch from Yolanda Robla.

* bpo-25745: Fixed leaking a userptr in curses panel destructor.

* bpo-26977: Removed unnecessary, and ignored, call to sum of squares
  helper in statistics.pvariance.

* bpo-26002: Use bisect in statistics.median instead of a linear
  search. Patch by Upendra Kuma.

* bpo-25974: Make use of new Decimal.as_integer_ratio() method in
  statistics module. Patch by Stefan Krah.

* bpo-26996: Add secrets module as described in **PEP 506**.

* bpo-26881: The modulefinder module now supports extended opcode
  arguments.

* bpo-23815: Fixed crashes related to directly created instances of
  types in _tkinter and curses.panel modules.

* bpo-17765: weakref.ref() no longer silently ignores keyword
  arguments. Patch by Georg Brandl.

* bpo-26873: xmlrpc now raises ResponseError on unsupported type tags
  instead of silently return incorrect result.

* bpo-26915: The __contains__ methods in the collections ABCs now
  check for identity before checking equality.  This better matches
  the behavior of the concrete classes, allows sensible handling of
  NaNs, and makes it easier to reason about container invariants.

* bpo-26711: Fixed the comparison of plistlib.Data with other types.

* bpo-24114: Fix an uninitialized variable in "ctypes.util". The bug
  only occurs on SunOS when the ctypes implementation searches for the
  "crle" program.  Patch by Xiang Zhang.  Tested on SunOS by Kees Bos.

* bpo-26864: In urllib.request, change the proxy bypass host checking
  against no_proxy to be case-insensitive, and to not match unrelated
  host names that happen to have a bypassed hostname as a suffix.
  Patch by Xiang Zhang.

* bpo-24902: Print server URL on http.server startup.  Initial patch
  by Felix Kaiser.

* bpo-25788: fileinput.hook_encoded() now supports an “errors”
  argument for passing to open.  Original patch by Joseph Hackman.

* bpo-26634: recursive_repr() now sets __qualname__ of wrapper.  Patch
  by Xiang Zhang.

* bpo-26804: urllib.request will prefer lower_case proxy environment
  variables over UPPER_CASE or Mixed_Case ones. Patch contributed by
  Hans-Peter Jansen.

* bpo-26837: assertSequenceEqual() now correctly outputs non-
  stringified differing items (like bytes in the -b mode).  This
  affects assertListEqual() and assertTupleEqual().

* bpo-26041: Remove “will be removed in Python 3.7” from deprecation
  messages of platform.dist() and platform.linux_distribution(). Patch
  by Kumaripaba Miyurusara Athukorala.

* bpo-26822: itemgetter, attrgetter and methodcaller objects no longer
  silently ignore keyword arguments.

* bpo-26733: Disassembling a class now disassembles class and static
  methods. Patch by Xiang Zhang.

* bpo-26801: Fix error handling in "shutil.get_terminal_size()", catch
  "AttributeError" instead of "NameError". Patch written by Emanuel
  Barry.

* bpo-24838: tarfile’s ustar and gnu formats now correctly calculate
  name and link field limits for multibyte character encodings like
  utf-8.

* bpo-26717: Stop encoding Latin-1-ized WSGI paths with UTF-8.  Patch
  by Anthony Sottile.

* bpo-26782: Add STARTUPINFO to subprocess.__all__ on Windows.

* bpo-26404: Add context manager to socketserver.  Patch by Aviv
  Palivoda.

* bpo-26735: Fix "os.urandom()" on Solaris 11.3 and newer when reading
  more than 1,024 bytes: call "getrandom()" multiple times with a
  limit of 1024 bytes per call.

* bpo-26585: Eliminate http.server._quote_html() and use
  html.escape(quote=False).  Patch by Xiang Zhang.

* bpo-26685: Raise OSError if closing a socket fails.

* bpo-16329: Add .webm to mimetypes.types_map.  Patch by Giampaolo
  Rodola’.

* bpo-13952: Add .csv to mimetypes.types_map.  Patch by Geoff Wilson.

* bpo-26587: the site module now allows .pth files to specify files to
  be added to sys.path (e.g. zip files).

* bpo-25609: Introduce contextlib.AbstractContextManager and
  typing.ContextManager.

* bpo-26709: Fixed Y2038 problem in loading binary PLists.

* bpo-23735: Handle terminal resizing with Readline 6.3+ by installing
  our own SIGWINCH handler.  Patch by Eric Price.

* bpo-25951: Change SSLSocket.sendall() to return None, as explicitly
  documented for plain socket objects.  Patch by Aviv Palivoda.

* bpo-26586: In http.server, respond with “413 Request header fields
  too large” if there are too many header fields to parse, rather than
  killing the connection and raising an unhandled exception.  Patch by
  Xiang Zhang.

* bpo-26676: Added missing XMLPullParser to ElementTree.__all__.

* bpo-22854: Change BufferedReader.writable() and
  BufferedWriter.readable() to always return False.

* bpo-26492: Exhausted iterator of array.array now conforms with the
  behavior of iterators of other mutable sequences: it lefts exhausted
  even if iterated array is extended.

* bpo-26641: doctest.DocFileTest and doctest.testfile() now support
  packages (module splitted into multiple directories) for the package
  parameter.

* bpo-25195: Fix a regression in mock.MagicMock. _Call is a subclass
  of tuple (changeset 3603bae63c13 only works for classes) so we need
  to implement __ne__ ourselves.  Patch by Andrew Plummer.

* bpo-26644: Raise ValueError rather than SystemError when a negative
  length is passed to SSLSocket.recv() or read().

* bpo-23804: Fix SSL recv(0) and read(0) methods to return zero bytes
  instead of up to 1024.

* bpo-26616: Fixed a bug in datetime.astimezone() method.

* bpo-26637: The "importlib" module now emits an "ImportError" rather
  than a "TypeError" if "__import__()" is tried during the Python
  shutdown process but "sys.path" is already cleared (set to "None").

* bpo-21925: "warnings.formatwarning()" now catches exceptions when
  calling "linecache.getline()" and
  "tracemalloc.get_object_traceback()" to be able to log
  "ResourceWarning" emitted late during the Python shutdown process.

* bpo-23848: On Windows, faulthandler.enable() now also installs an
  exception handler to dump the traceback of all Python threads on any
  Windows exception, not only on UNIX signals (SIGSEGV, SIGFPE,
  SIGABRT).

* bpo-26530: Add C functions "_PyTraceMalloc_Track()" and
  "_PyTraceMalloc_Untrack()" to track memory blocks using the
  "tracemalloc" module. Add "_PyTraceMalloc_GetTraceback()" to get the
  traceback of an object.

* bpo-26588: The _tracemalloc now supports tracing memory allocations
  of multiple address spaces (domains).

* bpo-24266: Ctrl+C during Readline history search now cancels the
  search mode when compiled with Readline 7.

* bpo-26590: Implement a safe finalizer for the _socket.socket type.
  It now releases the GIL to close the socket.

* bpo-18787: spwd.getspnam() now raises a PermissionError if the user
  doesn’t have privileges.

* bpo-26560: Avoid potential ValueError in BaseHandler.start_response.
  Initial patch by Peter Inglesby.

* bpo-26567: Add a new function "PyErr_ResourceWarning()" function to
  pass the destroyed object. Add a *source* attribute to
  "warnings.WarningMessage". Add warnings._showwarnmsg() which uses
  tracemalloc to get the traceback where source object was allocated.

* bpo-26569: Fix "pyclbr.readmodule()" and "pyclbr.readmodule_ex()" to
  support importing packages.

* bpo-26499: Account for remaining Content-Length in
  HTTPResponse.readline() and read1(). Based on patch by Silent Ghost.
  Also document that HTTPResponse now supports these methods.

* bpo-25320: Handle sockets in directories unittest discovery is
  scanning. Patch from Victor van den Elzen.

* bpo-16181: cookiejar.http2time() now returns None if year is higher
  than datetime.MAXYEAR.

* bpo-26513: Fixes platform module detection of Windows Server

* bpo-23718: Fixed parsing time in week 0 before Jan 1.  Original
  patch by Tamás Bence Gedai.

* bpo-26323: Add Mock.assert_called() and Mock.assert_called_once()
  methods to unittest.mock. Patch written by Amit Saha.

* bpo-20589: Invoking Path.owner() and Path.group() on Windows now
  raise NotImplementedError instead of ImportError.

* bpo-26177: Fixed the keys() method for Canvas and Scrollbar widgets.

* bpo-15068: Got rid of excessive buffering in fileinput. The bufsize
  parameter is now deprecated and ignored.

* bpo-19475: Added an optional argument timespec to the datetime
  isoformat() method to choose the precision of the time component.

* bpo-2202: Fix UnboundLocalError in
  AbstractDigestAuthHandler.get_algorithm_impls. Initial patch by
  Mathieu Dupuy.

* bpo-26167: Minimized overhead in copy.copy() and copy.deepcopy().
  Optimized copying and deepcopying bytearrays, NotImplemented,
  slices, short lists, tuples, dicts, sets.

* bpo-25718: Fixed pickling and copying the accumulate() iterator with
  total is None.

* bpo-26475: Fixed debugging output for regular expressions with the
  (?x) flag.

* bpo-26482: Allowed pickling recursive dequeues.

* bpo-26335: Make mmap.write() return the number of bytes written like
  other write methods.  Patch by Jakub Stasiak.

* bpo-26457: Fixed the subnets() methods in IP network classes for the
  case when resulting prefix length is equal to maximal prefix length.
  Based on patch by Xiang Zhang.

* bpo-26385: Remove the file if the internal open() call in
  NamedTemporaryFile() fails. Patch by Silent Ghost.

* bpo-26402: Fix XML-RPC client to retry when the server shuts down a
  persistent connection.  This was a regression related to the new
  http.client.RemoteDisconnected exception in 3.5.0a4.

* bpo-25913: Leading "<~" is optional now in base64.a85decode() with
  adobe=True.  Patch by Swati Jaiswal.

* bpo-26186: Remove an invalid type check in
  importlib.util.LazyLoader.

* bpo-26367: importlib.__import__() raises ImportError like
  builtins.__import__() when "level" is specified but without an
  accompanying package specified.

* bpo-26309: In the “socketserver” module, shut down the request
  (closing the connected socket) when verify_request() returns false.
  Patch by Aviv Palivoda.

* bpo-23430: Change the socketserver module to only catch exceptions
  raised from a request handler that are derived from Exception
  (instead of BaseException). Therefore SystemExit and
  KeyboardInterrupt no longer trigger the handle_error() method, and
  will now to stop a single-threaded server.

* bpo-25995: os.walk() no longer uses FDs proportional to the tree
  depth.

* bpo-25994: Added the close() method and the support of the context
  manager protocol for the os.scandir() iterator.

* bpo-23992: multiprocessing: make MapResult not fail-fast upon
  exception.

* bpo-26243: Support keyword arguments to zlib.compress().  Patch by
  Aviv Palivoda.

* bpo-26117: The os.scandir() iterator now closes file descriptor not
  only when the iteration is finished, but when it was failed with
  error.

* bpo-25949: __dict__ for an OrderedDict instance is now created only
  when needed.

* bpo-25911: Restored support of bytes paths in os.walk() on Windows.

* bpo-26045: Add UTF-8 suggestion to error message when posting a non-
  Latin-1 string with http.client.

* bpo-26039: Added zipfile.ZipInfo.from_file() and
  zipinfo.ZipInfo.is_dir(). Patch by Thomas Kluyver.

* bpo-12923: Reset FancyURLopener’s redirect counter even if there is
  an exception. Based on patches by Brian Brazil and Daniel Rocco.

* bpo-25945: Fixed a crash when unpickle the functools.partial object
  with wrong state. Fixed a leak in failed functools.partial
  constructor. “args” and “keywords” attributes of functools.partial
  have now always types tuple and dict correspondingly.

* bpo-26202: copy.deepcopy() now correctly copies range() objects with
  non-atomic attributes.

* bpo-23076: Path.glob() now raises a ValueError if it’s called with
  an invalid pattern. Patch by Thomas Nyberg.

* bpo-19883: Fixed possible integer overflows in zipimport.

* bpo-26227: On Windows, getnameinfo(), gethostbyaddr() and
  gethostbyname_ex() functions of the socket module now decode the
  hostname from the ANSI code page rather than UTF-8.

* bpo-26099: The site module now writes an error into stderr if
  sitecustomize module can be imported but executing the module raise
  an ImportError. Same change for usercustomize.

* bpo-26147: xmlrpc now works with strings not encodable with used
  non-UTF-8 encoding.

* bpo-25935: Garbage collector now breaks reference loops with
  OrderedDict.

* bpo-16620: Fixed AttributeError in msilib.Directory.glob().

* bpo-26013: Added compatibility with broken protocol 2 pickles
  created in old Python 3 versions (3.4.3 and lower).

* bpo-26129: Deprecated accepting non-integers in grp.getgrgid().

* bpo-25850: Use cross-compilation by default for 64-bit Windows.

* bpo-25822: Add docstrings to the fields of urllib.parse results.
  Patch contributed by Swati Jaiswal.

* bpo-22642: Convert trace module option parsing mechanism to
  argparse. Patch contributed by SilentGhost.

* bpo-24705: Fix sysconfig._parse_makefile not expanding ${} vars
  appearing before $() vars.

* bpo-26069: Remove the deprecated apis in the trace module.

* bpo-22138: Fix mock.patch behavior when patching descriptors.
  Restore original values after patching. Patch contributed by Sean
  McCully.

* bpo-25672: In the ssl module, enable the SSL_MODE_RELEASE_BUFFERS
  mode option if it is safe to do so.

* bpo-26012: Don’t traverse into symlinks for "**" pattern in
  pathlib.Path.[r]glob().

* bpo-24120: Ignore PermissionError when traversing a tree with
  pathlib.Path.[r]glob(). Patch by Ulrich Petri.

* bpo-21815: Accept ] characters in the data portion of imap
  responses, in order to handle the flags with square brackets
  accepted and produced by servers such as gmail.

* bpo-25447: fileinput now uses sys.stdin as-is if it does not have a
  buffer attribute (restores backward compatibility).

* bpo-25971: Optimized creating Fractions from floats by 2 times and
  from Decimals by 3 times.

* bpo-25802: Document as deprecated the remaining implementations of
  importlib.abc.Loader.load_module().

* bpo-25928: Add Decimal.as_integer_ratio().

* bpo-25447: Copying the lru_cache() wrapper object now always works,
  independently from the type of the wrapped object (by returning the
  original object unchanged).

* bpo-25768: Have the functions in compileall return booleans instead
  of ints and add proper documentation and tests for the return
  values.

* bpo-24103: Fixed possible use after free in
  ElementTree.XMLPullParser.

* bpo-25860: os.fwalk() no longer skips remaining directories when
  error occurs. Original patch by Samson Lee.

* bpo-25914: Fixed and simplified OrderedDict.__sizeof__.

* bpo-25869: Optimized deepcopying ElementTree; it is now 20 times
  faster.

* bpo-25873: Optimized iterating ElementTree.  Iterating elements
  Element.iter() is now 40% faster, iterating text Element.itertext()
  is now up to 2.5 times faster.

* bpo-25902: Fixed various refcount issues in ElementTree iteration.

* bpo-22227: The TarFile iterator is reimplemented using generator.
  This implementation is simpler that using class.

* bpo-25638: Optimized ElementTree.iterparse(); it is now 2x faster.
  Optimized ElementTree parsing; it is now 10% faster.

* bpo-25761: Improved detecting errors in broken pickle data.

* bpo-25717: Restore the previous behaviour of tolerating most fstat()
  errors when opening files.  This was a regression in 3.5a1, and
  stopped anonymous temporary files from working in special cases.

* bpo-24903: Fix regression in number of arguments compileall accepts
  when ‘-d’ is specified.  The check on the number of arguments has
  been dropped completely as it never worked correctly anyway.

* bpo-25764: In the subprocess module, preserve any exception caused
  by fork() failure when preexec_fn is used.

* bpo-25771: Tweak the exception message for
  importlib.util.resolve_name() when ‘package’ isn’t specified but
  necessary.

* bpo-6478: _strptime’s regexp cache now is reset after changing
  timezone with time.tzset().

* bpo-14285: When executing a package with the “python -m package”
  option, and package initialization fails, a proper traceback is now
  reported.  The “runpy” module now lets exceptions from package
  initialization pass back to the caller, rather than raising
  ImportError.

* bpo-19771: Also in runpy and the “-m” option, omit the irrelevant
  message “… is a package and cannot be directly executed” if the
  package could not even be initialized (e.g. due to a bad "*.pyc"
  file).

* bpo-25177: Fixed problem with the mean of very small and very large
  numbers. As a side effect, statistics.mean and statistics.variance
  should be significantly faster.

* bpo-25718: Fixed copying object with state with boolean value is
  false.

* bpo-10131: Fixed deep copying of minidom documents.  Based on patch
  by Marian Ganisin.

* bpo-7990: dir() on ElementTree.Element now lists properties: “tag”,
  “text”, “tail” and “attrib”.  Original patch by Santoso Wijaya.

* bpo-25725: Fixed a reference leak in pickle.loads() when unpickling
  invalid data including tuple instructions.

* bpo-25663: In the Readline completer, avoid listing duplicate global
  names, and search the global namespace before searching builtins.

* bpo-25688: Fixed file leak in ElementTree.iterparse() raising an
  error.

* bpo-23914: Fixed SystemError raised by unpickler on broken pickle
  data.

* bpo-25691: Fixed crash on deleting ElementTree.Element attributes.

* bpo-25624: ZipFile now always writes a ZIP_STORED header for
  directory entries.  Patch by Dingyuan Wang.

* bpo-25626: Change three zlib functions to accept sizes that fit in
  Py_ssize_t, but internally cap those sizes to UINT_MAX.  This
  resolves a regression in 3.5 where GzipFile.read() failed to read
  chunks larger than 2 or 4 GiB.  The change affects the
  zlib.Decompress.decompress() max_length parameter, the
  zlib.decompress() bufsize parameter, and the zlib.Decompress.flush()
  length parameter.

* bpo-25583: Avoid incorrect errors raised by
  os.makedirs(exist_ok=True) when the OS gives priority to errors such
  as EACCES over EEXIST.

* bpo-25593: Change semantics of EventLoop.stop() in asyncio.

* bpo-6973: When we know a subprocess.Popen process has died, do not
  allow the send_signal(), terminate(), or kill() methods to do
  anything as they could potentially signal a different process.

* bpo-23883: Added missing APIs to __all__ to match the documented
  APIs for the following modules: calendar, csv, enum, fileinput,
  ftplib, logging, optparse, tarfile, threading and wave.  Also added
  a test.support.check__all__() helper. Patches by Jacek Kołodziej,
  Mauro S. M. Rodrigues and Joel Taddei.

* bpo-25590: In the Readline completer, only call getattr() once per
  attribute.  Also complete names of attributes such as properties and
  slots which are listed by dir() but not yet created on an instance.

* bpo-25498: Fix a crash when garbage-collecting ctypes objects
  created by wrapping a memoryview.  This was a regression made in
  3.5a1.  Based on patch by Eryksun.

* bpo-25584: Added “escape” to the __all__ list in the glob module.

* bpo-25584: Fixed recursive glob() with patterns starting with "**".

* bpo-25446: Fix regression in smtplib’s AUTH LOGIN support.

* bpo-18010: Fix the pydoc web server’s module search function to
  handle exceptions from importing packages.

* bpo-25554: Got rid of circular references in regular expression
  parsing.

* bpo-18973: Command-line interface of the calendar module now uses
  argparse instead of optparse.

* bpo-25510: fileinput.FileInput.readline() now returns b’’ instead of
  ‘’ at the end if the FileInput was opened with binary mode. Patch by
  Ryosuke Ito.

* bpo-25503: Fixed inspect.getdoc() for inherited docstrings of
  properties. Original patch by John Mark Vandenberg.

* bpo-25515: Always use os.urandom as a source of randomness in
  uuid.uuid4.

* bpo-21827: Fixed textwrap.dedent() for the case when largest common
  whitespace is a substring of smallest leading whitespace. Based on
  patch by Robert Li.

* bpo-25447: The lru_cache() wrapper objects now can be copied and
  pickled (by returning the original object unchanged).

* bpo-25390: typing: Don’t crash on Union[str, Pattern].

* bpo-25441: asyncio: Raise error from drain() when socket is closed.

* bpo-25410: Cleaned up and fixed minor bugs in C implementation of
  OrderedDict.

* bpo-25411: Improved Unicode support in SMTPHandler through better
  use of the email package. Thanks to user simon04 for the patch.

* Move the imp module from a PendingDeprecationWarning to
  DeprecationWarning.

* bpo-25407: Remove mentions of the formatter module being removed in
  Python 3.6.

* bpo-25406: Fixed a bug in C implementation of
  OrderedDict.move_to_end() that caused segmentation fault or hang in
  iterating after moving several items to the start of ordered dict.

* bpo-25382: pickletools.dis() now outputs implicit memo index for the
  MEMOIZE opcode.

* bpo-25357: Add an optional newline parameter to
  binascii.b2a_base64(). base64.b64encode() uses it to avoid a memory
  copy.

* bpo-24164: Objects that need calling "__new__" with keyword
  arguments, can now be pickled using pickle protocols older than
  protocol version 4.

* bpo-25364: zipfile now works in threads disabled builds.

* bpo-25328: smtpd’s SMTPChannel now correctly raises a ValueError if
  both decode_data and enable_SMTPUTF8 are set to true.

* bpo-16099: RobotFileParser now supports Crawl-delay and Request-rate
  extensions.  Patch by Nikolay Bogoychev.

* bpo-25316: distutils raises OSError instead of
  DistutilsPlatformError when MSVC is not installed.

* bpo-25380: Fixed protocol for the STACK_GLOBAL opcode in
  pickletools.opcodes.

* bpo-23972: Updates asyncio datagram create method allowing reuseport
  and reuseaddr socket options to be set prior to binding the socket.
  Mirroring the existing asyncio create_server method the reuseaddr
  option for datagram sockets defaults to True if the O/S is ‘posix’
  (except if the platform is Cygwin). Patch by Chris Laws.

* bpo-25304: Add asyncio.run_coroutine_threadsafe().  This lets you
  submit a coroutine to a loop from another thread, returning a
  concurrent.futures.Future.  By Vincent Michel.

* bpo-25232: Fix CGIRequestHandler to split the query from the URL at
  the first question mark (?) rather than the last. Patch from Xiang
  Zhang.

* bpo-24657: Prevent CGIRequestHandler from collapsing slashes in the
  query part of the URL as if it were a path. Patch from Xiang Zhang.

* bpo-25287: Don’t add crypt.METHOD_CRYPT to crypt.methods if it’s not
  supported. Check if it is supported, it may not be supported on
  OpenBSD for example.

* bpo-23600: Default implementation of tzinfo.fromutc() was returning
  wrong results in some cases.

* bpo-25203: Failed readline.set_completer_delims() no longer left the
  module in inconsistent state.

* bpo-25011: rlcompleter now omits private and special attribute names
  unless the prefix starts with underscores.

* bpo-25209: rlcompleter now can add a space or a colon after
  completed keyword.

* bpo-22241: timezone.utc name is now plain ‘UTC’, not ‘UTC-00:00’.

* bpo-23517: fromtimestamp() and utcfromtimestamp() methods of
  datetime.datetime now round microseconds to nearest with ties going
  to nearest even integer (ROUND_HALF_EVEN), as round(float), instead
  of rounding towards -Infinity (ROUND_FLOOR).

* bpo-23552: Timeit now warns when there is substantial (4x) variance
  between best and worst times. Patch from Serhiy Storchaka.

* bpo-24633: site-packages/README -> README.txt.

* bpo-24879: help() and pydoc can now list named tuple fields in the
  order they were defined rather than alphabetically.  The ordering is
  determined by the _fields attribute if present.

* bpo-24874: Improve speed of itertools.cycle() and make its pickle
  more compact.

* Fix crash in itertools.cycle.__setstate__() when the first argument
  wasn’t a list.

* bpo-20059: urllib.parse raises ValueError on all invalid ports.
  Patch by Martin Panter.

* bpo-24360: Improve __repr__ of argparse.Namespace() for invalid
  identifiers.  Patch by Matthias Bussonnier.

* bpo-23426: run_setup was broken in distutils. Patch from Alexander
  Belopolsky.

* bpo-13938: 2to3 converts StringTypes to a tuple. Patch from Mark
  Hammond.

* bpo-2091: open() accepted a ‘U’ mode string containing ‘+’, but ‘U’
  can only be used with ‘r’. Patch from Jeff Balogh and John O’Connor.

* bpo-8585: improved tests for zipimporter2. Patch from Mark Lawrence.

* bpo-18622: unittest.mock.mock_open().reset_mock would recurse
  infinitely. Patch from Nicola Palumbo and Laurent De Buyst.

* bpo-24426: Fast searching optimization in regular expressions now
  works for patterns that starts with capturing groups.  Fast
  searching optimization now can’t be disabled at compile time.

* bpo-23661: unittest.mock side_effects can now be exceptions again.
  This was a regression vs Python 3.4. Patch from Ignacio Rossi

* bpo-13248: Remove deprecated inspect.getmoduleinfo function.

* bpo-25578: Fix (another) memory leak in SSLSocket.getpeercer().

* bpo-25530: Disable the vulnerable SSLv3 protocol by default when
  creating ssl.SSLContext.

* bpo-25569: Fix memory leak in SSLSocket.getpeercert().

* bpo-25471: Sockets returned from accept() shouldn’t appear to be
  nonblocking.

* bpo-25319: When threading.Event is reinitialized, the underlying
  condition should use a regular lock rather than a recursive lock.

* Skip getaddrinfo if host is already resolved. Patch by A. Jesse
  Jiryu Davis.

* bpo-26050: Add asyncio.StreamReader.readuntil() method. Patch by
  Марк Коренберг.

* bpo-25924: Avoid unnecessary serialization of getaddrinfo(3) calls
  on OS X versions 10.5 or higher.  Original patch by A. Jesse Jiryu
  Davis.

* bpo-26406: Avoid unnecessary serialization of getaddrinfo(3) calls
  on current versions of OpenBSD and NetBSD.  Patch by A. Jesse Jiryu
  Davis.

* bpo-26848: Fix asyncio/subprocess.communicate() to handle empty
  input. Patch by Jack O’Connor.

* bpo-27040: Add loop.get_exception_handler method

* bpo-27041: asyncio: Add loop.create_future method


IDLE
----

* bpo-20640: Add tests for idlelib.configHelpSourceEdit. Patch by
  Saimadhav Heblikar.

* In the ‘IDLE-console differences’ section of the IDLE doc, clarify
  how running with IDLE affects sys.modules and the standard streams.

* bpo-25507: fix incorrect change in IOBinding that prevented
  printing. Augment IOBinding htest to include all major IOBinding
  functions.

* bpo-25905: Revert unwanted conversion of ‘ to ’ RIGHT SINGLE
  QUOTATION MARK in README.txt and open this and NEWS.txt with
  ‘ascii’. Re-encode CREDITS.txt to utf-8 and open it with ‘utf-8’.

* bpo-15348: Stop the debugger engine (normally in a user process)
  before closing the debugger window (running in the IDLE process).
  This prevents the RuntimeErrors that were being caught and ignored.

* bpo-24455: Prevent IDLE from hanging when a) closing the shell while
  the debugger is active (15347); b) closing the debugger with the [X]
  button (15348); and c) activating the debugger when already active
  (24455). The patch by Mark Roseman does this by making two changes.
  1. Suspend and resume the gui.interaction method with the tcl vwait
  mechanism intended for this purpose (instead of root.mainloop &
  .quit). 2. In gui.run, allow any existing interaction to terminate
  first.

* Change ‘The program’ to ‘Your program’ in an IDLE ‘kill program?’
  message to make it clearer that the program referred to is the
  currently running user program, not IDLE itself.

* bpo-24750: Improve the appearance of the IDLE editor window status
  bar. Patch by Mark Roseman.

* bpo-25313: Change the handling of new built-in text color themes to
  better address the compatibility problem introduced by the addition
  of IDLE Dark. Consistently use the revised idleConf.CurrentTheme
  everywhere in idlelib.

* bpo-24782: Extension configuration is now a tab in the IDLE
  Preferences dialog rather than a separate dialog.  The former tabs
  are now a sorted list.  Patch by Mark Roseman.

* bpo-22726: Re-activate the config dialog help button with some
  content about the other buttons and the new IDLE Dark theme.

* bpo-24820: IDLE now has an ‘IDLE Dark’ built-in text color theme. It
  is more or less IDLE Classic inverted, with a cobalt blue
  background. Strings, comments, keywords, … are still green, red,
  orange, … . To use it with IDLEs released before November 2015, hit
  the ‘Save as New Custom Theme’ button and enter a new name, such as
  ‘Custom Dark’.  The custom theme will work with any IDLE release,
  and can be modified.

* bpo-25224: README.txt is now an idlelib index for IDLE developers
  and curious users. The previous user content is now in the IDLE doc
  chapter. ‘IDLE’ now means ‘Integrated Development and Learning
  Environment’.

* bpo-24820: Users can now set breakpoint colors in Settings -> Custom
  Highlighting. Original patch by Mark Roseman.

* bpo-24972: Inactive selection background now matches active
  selection background, as configured by users, on all systems.  Found
  items are now always highlighted on Windows.  Initial patch by Mark
  Roseman.

* bpo-24570: Idle: make calltip and completion boxes appear on Macs
  affected by a tk regression.  Initial patch by Mark Roseman.

* bpo-24988: Idle ScrolledList context menus (used in debugger) now
  work on Mac Aqua. Patch by Mark Roseman.

* bpo-24801: Make right-click for context menu work on Mac Aqua. Patch
  by Mark Roseman.

* bpo-25173: Associate tkinter messageboxes with a specific widget.
  For Mac OSX, make them a ‘sheet’.  Patch by Mark Roseman.

* bpo-25198: Enhance the initial html viewer now used for Idle Help.
  Properly indent fixed-pitch text (patch by Mark Roseman). Give code
  snippet a very Sphinx-like light blueish-gray background. Re-use
  initial width and height set by users for shell and editor. When the
  Table of Contents (TOC) menu is used, put the section header at the
  top of the screen.

* bpo-25225: Condense and rewrite Idle doc section on text colors.

* bpo-21995: Explain some differences between IDLE and console Python.

* bpo-22820: Explain need for *print* when running file from Idle
  editor.

* bpo-25224: Doc: augment Idle feature list and no-subprocess section.

* bpo-25219: Update doc for Idle command line options. Some were
  missing and notes were not correct.

* bpo-24861: Most of idlelib is private and subject to change. Use
  idleib.idle.* to start Idle. See idlelib.__init__.__doc__.

* bpo-25199: Idle: add synchronization comments for future
  maintainers.

* bpo-16893: Replace help.txt with help.html for Idle doc display. The
  new idlelib/help.html is rstripped Doc/build/html/library/idle.html.
  It looks better than help.txt and will better document Idle as
  released. The tkinter html viewer that works for this file was
  written by Rose Roseman. The now unused EditorWindow.HelpDialog
  class and helt.txt file are deprecated.

* bpo-24199: Deprecate unused idlelib.idlever with possible removal in
  3.6.

* bpo-24790: Remove extraneous code (which also create 2 & 3
  conflicts).


Documentation
-------------

* bpo-26736: Used HTTPS for external links in the documentation if
  possible.

* bpo-6953: Rework the Readline module documentation to group related
  functions together, and add more details such as what underlying
  Readline functions and variables are accessed.

* bpo-23606: Adds note to ctypes documentation regarding cdll.msvcrt.

* bpo-24952: Clarify the default size argument of stack_size() in the
  “threading” and “_thread” modules. Patch from Mattip.

* bpo-26014: Update 3.x packaging documentation: * “See also” links to
  the new docs are now provided in the legacy pages * links to
  setuptools documentation have been updated


Tests
-----

* bpo-21916: Added tests for the turtle module.  Patch by ingrid,
  Gregory Loyse and Jelle Zijlstra.

* bpo-26295: When using “python3 -m test –testdir=TESTDIR”, regrtest
  doesn’t add “test.” prefix to test module names.

* bpo-26523: The multiprocessing thread pool
  (multiprocessing.dummy.Pool) was untested.

* bpo-26015: Added new tests for pickling iterators of mutable
  sequences.

* bpo-26325: Added test.support.check_no_resource_warning() to check
  that no ResourceWarning is emitted.

* bpo-25940: Changed test_ssl to use its internal local server more.
  This avoids relying on svn.python.org, which recently changed root
  certificate.

* bpo-25616: Tests for OrderedDict are extracted from test_collections
  into separate file test_ordered_dict.

* bpo-25449: Added tests for OrderedDict subclasses.

* bpo-25188: Add -P/–pgo to test.regrtest to suppress error output
  when running the test suite for the purposes of a PGO build. Initial
  patch by Alecsandru Patrascu.

* bpo-22806: Add "python -m test --list-tests" command to list tests.

* bpo-18174: "python -m test --huntrleaks ..." now also checks for
  leak of file descriptors. Patch written by Richard Oudkerk.

* bpo-25260: Fix "python -m test --coverage" on Windows. Remove the
  list of ignored directories.

* "PCbuild\rt.bat" now accepts an unlimited number of arguments to
  pass along to regrtest.py.  Previously there was a limit of 9.

* bpo-26583: Skip test_timestamp_overflow in test_import if bytecode
  files cannot be written.


Build
-----

* bpo-21277: Don’t try to link _ctypes with a ffi_convenience library.

* bpo-26884: Fix linking extension modules for cross builds. Patch by
  Xavier de Gaye.

* bpo-26932: Fixed support of RTLD_* constants defined as enum values,
  not via macros (in particular on Android).  Patch by Chi Hsuan Yen.

* bpo-22359: Disable the rules for running _freeze_importlib and pgen
  when cross-compiling.  The output of these programs is normally
  saved with the source code anyway, and is still regenerated when
  doing a native build. Patch by Xavier de Gaye.

* bpo-21668: Link audioop, _datetime, _ctypes_test modules to libm,
  except on Mac OS X. Patch written by Chi Hsuan Yen.

* bpo-25702: A –with-lto configure option has been added that will
  enable link time optimizations at build time during a make profile-
  opt. Some compilers and toolchains are known to not produce stable
  code when using LTO, be sure to test things thoroughly before
  relying on it. It can provide a few % speed up over profile-opt
  alone.

* bpo-26624: Adds validation of ucrtbase[d].dll version with warning
  for old versions.

* bpo-17603: Avoid error about nonexistent fileblocks.o file by using
  a lower-level check for st_blocks in struct stat.

* bpo-26079: Fixing the build output folder for tix-8.4.3.6. Patch by
  Bjoern Thiel.

* bpo-26465: Update Windows builds to use OpenSSL 1.0.2g.

* bpo-25348: Added "--pgo" and "--pgo-job" arguments to
  "PCbuild\build.bat" for building with Profile-Guided Optimization.
  The old "PCbuild\build_pgo.bat" script is removed.

* bpo-25827: Add support for building with ICC to "configure",
  including a new "--with-icc" flag.

* bpo-25696: Fix installation of Python on UNIX with make -j9.

* bpo-24986: It is now possible to build Python on Windows without
  errors when external libraries are not available.

* bpo-24421: Compile Modules/_math.c once, before building extensions.
  Previously it could fail to compile properly if the math and cmath
  builds were concurrent.

* bpo-26465: Update OS X 10.5+ 32-bit-only installer to build and link
  with OpenSSL 1.0.2g.

* bpo-26268: Update Windows builds to use OpenSSL 1.0.2f.

* bpo-25136: Support Apple Xcode 7’s new textual SDK stub libraries.

* bpo-24324: Do not enable unreachable code warnings when using gcc as
  the option does not work correctly in older versions of gcc and has
  been silently removed as of gcc-4.5.


Windows
-------

* bpo-27053: Updates make_zip.py to correctly generate library ZIP
  file.

* bpo-26268: Update the prepare_ssl.py script to handle OpenSSL
  releases that don’t include the contents of the include directory
  (that is, 1.0.2e and later).

* bpo-26071: bdist_wininst created binaries fail to start and find
  32bit Python

* bpo-26073: Update the list of magic numbers in launcher

* bpo-26065: Excludes venv from library when generating embeddable
  distro.

* bpo-25022: Removed very outdated PC/example_nt/ directory.


Tools/Demos
-----------

* bpo-26799: Fix python-gdb.py: don’t get C types once when the Python
  code is loaded, but get C types on demand. The C types can change if
  python-gdb.py is loaded before the Python executable. Patch written
  by Thomas Ilsche.

* bpo-26271: Fix the Freeze tool to properly use flags passed through
  configure. Patch by Daniel Shaulov.

* bpo-26489: Add dictionary unpacking support to
  Tools/parser/unparse.py. Patch by Guo Ci Teo.

* bpo-26316: Fix variable name typo in Argument Clinic.

* bpo-25440: Fix output of python-config –extension-suffix.

* bpo-25154: The pyvenv script has been deprecated in favour of
  "python3 -m venv".


C API
-----

* bpo-26312: SystemError is now raised in all programming bugs with
  using PyArg_ParseTupleAndKeywords().  RuntimeError did raised before
  in some programming bugs.

* bpo-26198: ValueError is now raised instead of TypeError on buffer
  overflow in parsing “es#” and “et#” format units.  SystemError is
  now raised instead of TypeError on programmatical error in parsing
  format string.


Python 3.5.5 final
==================

*Release date: 2018-02-04*

There were no new changes in version 3.5.5.


Python 3.5.5 release candidate 1
================================

*Release date: 2018-01-23*


Security
--------

* bpo-32551: The "sys.path[0]" initialization change for bpo-29139
  caused a regression by revealing an inconsistency in how sys.path is
  initialized when executing "__main__" from a zipfile, directory, or
  other import location. This is considered a potential security
  issue, as it may lead to privileged processes unexpectedly loading
  code from user controlled directories in situations where that was
  not previously the case. The interpreter now consistently avoids
  ever adding the import location’s parent directory to "sys.path",
  and ensures no other "sys.path" entries are inadvertently modified
  when inserting the import location named on the command line.
  (Originally reported as bpo-29723 against Python 3.6rc1, but it was
  missed at the time that the then upcoming Python 3.5.4 release would
  also be affected)

* bpo-30657: Fixed possible integer overflow in PyBytes_DecodeEscape,
  CVE-2017-1000158. Original patch by Jay Bosamiya; rebased to Python
  3 by Miro Hrončok.

* bpo-30947: Upgrade libexpat embedded copy from version 2.2.1 to
  2.2.3 to get security fixes.


Core and Builtins
-----------------

* bpo-31095: Fix potential crash during GC caused by "tp_dealloc"
  which doesn’t call "PyObject_GC_UnTrack()".


Library
-------

* bpo-32072: Fixed issues with binary plists: Fixed saving bytearrays.
  Identical objects will be saved only once. Equal references will be
  load as identical objects. Added support for saving and loading
  recursive data structures.

* bpo-31170: expat: Update libexpat from 2.2.3 to 2.2.4. Fix copying
  of partial characters for UTF-8 input (libexpat bug 115):
  https://github.com/libexpat/libexpat/issues/115


Python 3.5.4 final
==================

*Release date: 2017-08-07*


Library
-------

* bpo-30119: ftplib.FTP.putline() now throws ValueError on commands
  that contains CR or LF. Patch by Dong-hee Na.


Python 3.5.4 release candidate 1
================================

*Release date: 2017-07-23*


Security
--------

* bpo-30730: Prevent environment variables injection in subprocess on
  Windows.  Prevent passing other environment variables and command
  arguments.

* bpo-30694: Upgrade expat copy from 2.2.0 to 2.2.1 to get fixes of
  multiple security vulnerabilities including: CVE-2017-9233 (External
  entity infinite loop DoS), CVE-2016-9063 (Integer overflow, re-fix),
  CVE-2016-0718 (Fix regression bugs from 2.2.0’s fix to
  CVE-2016-0718) and CVE-2012-0876 (Counter hash flooding with
  SipHash). Note: the CVE-2016-5300 (Use os-specific entropy sources
  like getrandom) doesn’t impact Python, since Python already gets
  entropy from the OS to set the expat secret using
  "XML_SetHashSalt()".

* bpo-30500: Fix urllib.parse.splithost() to correctly parse
  fragments. For example, "splithost('//127.0.0.1#@evil.com/')" now
  correctly returns the "127.0.0.1" host, instead of treating
  "@evil.com" as the host in an authentication ("login@host").

* bpo-29591: Update expat copy from 2.1.1 to 2.2.0 to get fixes of
  CVE-2016-0718 and CVE-2016-4472. See
  https://sourceforge.net/p/expat/bugs/537/ for more information.


Core and Builtins
-----------------

* bpo-30876: Relative import from unloaded package now reimports the
  package instead of failing with SystemError.  Relative import from
  non-package now fails with ImportError rather than SystemError.

* bpo-30765: Avoid blocking in pthread_mutex_lock() when
  PyThread_acquire_lock() is asked not to block.

* bpo-27945: Fixed various segfaults with dict when input collections
  are mutated during searching, inserting or comparing.  Based on
  patches by Duane Griffin and Tim Mitchell.

* bpo-25794: Fixed type.__setattr__() and type.__delattr__() for non-
  interned attribute names.  Based on patch by Eryk Sun.

* bpo-29935: Fixed error messages in the index() method of tuple, list
  and deque when pass indices of wrong type.

* bpo-28876: "bool(range)" works even if "len(range)" raises
  "OverflowError".

* bpo-29600: Fix wrapping coroutine return values in StopIteration.

* bpo-29537: Restore runtime compatibility with bytecode files
  generated by CPython 3.5.0 to 3.5.2, and adjust the eval loop to
  avoid the problems that could be caused by the malformed variant of
  the BUILD_MAP_UNPACK_WITH_CALL opcode that they may contain. Patch
  by Petr Viktorin, Serhiy Storchaka, and Nick Coghlan.

* bpo-28598: Support __rmod__ for subclasses of str being called
  before str.__mod__. Patch by Martijn Pieters.

* bpo-29602: Fix incorrect handling of signed zeros in complex
  constructor for complex subclasses and for inputs having a
  __complex__ method. Patch by Serhiy Storchaka.

* bpo-29347: Fixed possibly dereferencing undefined pointers when
  creating weakref objects.

* bpo-29438: Fixed use-after-free problem in key sharing dict.

* bpo-29319: Prevent RunMainFromImporter overwriting sys.path[0].

* bpo-29337: Fixed possible BytesWarning when compare the code
  objects. Warnings could be emitted at compile time.

* bpo-29478: If max_line_length=None is specified while using the
  Compat32 policy, it is no longer ignored.  Patch by Mircea Cosbuc.


Library
-------

* bpo-29403: Fix "unittest.mock"’s autospec to not fail on method-
  bound builtin functions.  Patch by Aaron Gallagher.

* bpo-30961: Fix decrementing a borrowed reference in tracemalloc.

* bpo-30886: Fix multiprocessing.Queue.join_thread(): it now waits
  until the thread completes, even if the thread was started by the
  same process which created the queue.

* bpo-29854: Fix segfault in readline when using readline’s history-
  size option.  Patch by Nir Soffer.

* bpo-30807: signal.setitimer() may disable the timer when passed a
  tiny value. Tiny values (such as 1e-6) are valid non-zero values for
  setitimer(), which is specified as taking microsecond-resolution
  intervals. However, on some platform, our conversion routine could
  convert 1e-6 into a zero interval, therefore disabling the timer
  instead of (re-)scheduling it.

* bpo-30441: Fix bug when modifying os.environ while iterating over it

* bpo-30532: Fix email header value parser dropping folding white
  space in certain cases.

* bpo-29169: Update zlib to 1.2.11.

* bpo-30879: os.listdir() and os.scandir() now emit bytes names when
  called with bytes-like argument.

* bpo-30746: Prohibited the ‘=’ character in environment variable
  names in "os.putenv()" and "os.spawn*()".

* bpo-29755: Fixed the lgettext() family of functions in the gettext
  module. They now always return bytes.

* bpo-30645: Fix path calculation in imp.load_package(), fixing it for
  cases when a package is only shipped with bytecodes. Patch by
  Alexandru Ardelean.

* bpo-23890: unittest.TestCase.assertRaises() now manually breaks a
  reference cycle to not keep objects alive longer than expected.

* bpo-30149: inspect.signature() now supports callables with variable-
  argument parameters wrapped with partialmethod. Patch by Dong-hee
  Na.

* bpo-29931: Fixed comparison check for ipaddress.ip_interface
  objects. Patch by Sanjay Sundaresan.

* bpo-24484: Avoid race condition in multiprocessing cleanup.

* bpo-28994: The traceback no longer displayed for SystemExit raised
  in a callback registered by atexit.

* bpo-30508: Don’t log exceptions if Task/Future “cancel()” method was
  called.

* bpo-28556: Updates to typing module: Add generic
  AsyncContextManager, add support for ContextManager on all versions.
  Original PRs by Jelle Zijlstra and Ivan Levkivskyi

* bpo-29870: Fix ssl sockets leaks when connection is aborted in
  asyncio/ssl implementation. Patch by Michaël Sghaïer.

* bpo-29743: Closing transport during handshake process leaks open
  socket. Patch by Nikolay Kim

* bpo-27585: Fix waiter cancellation in asyncio.Lock. Patch by Mathieu
  Sornay.

* bpo-30418: On Windows, subprocess.Popen.communicate() now also
  ignore EINVAL on stdin.write() if the child process is still running
  but closed the pipe.

* bpo-30378: Fix the problem that logging.handlers.SysLogHandler
  cannot handle IPv6 addresses.

* bpo-29960: Preserve generator state when _random.Random.setstate()
  raises an exception. Patch by Bryan Olson.

* bpo-30414: multiprocessing.Queue._feed background running thread do
  not break from main loop on exception.

* bpo-30003: Fix handling escape characters in HZ codec.  Based on
  patch by Ma Lin.

* bpo-30301: Fix AttributeError when using SimpleQueue.empty() under
  *spawn* and *forkserver* start methods.

* bpo-30329: imaplib and poplib now catch the Windows socket WSAEINVAL
  error (code 10022) on shutdown(SHUT_RDWR): An invalid operation was
  attempted. This error occurs sometimes on SSL connections.

* bpo-30375: Warnings emitted when compile a regular expression now
  always point to the line in the user code.  Previously they could
  point into inners of the re module if emitted from inside of groups
  or conditionals.

* bpo-30048: Fixed "Task.cancel()" can be ignored when the task is
  running coroutine and the coroutine returned without any more
  "await".

* bpo-29990: Fix range checking in GB18030 decoder.  Original patch by
  Ma Lin.

* bpo-26293: Change resulted because of zipfile breakage. (See also:
  bpo-29094)

* bpo-30243: Removed the __init__ methods of _json’s scanner and
  encoder. Misusing them could cause memory leaks or crashes.  Now
  scanner and encoder objects are completely initialized in the
  __new__ methods.

* bpo-30185: Avoid KeyboardInterrupt tracebacks in forkserver helper
  process when Ctrl-C is received.

* bpo-28556: Various updates to typing module: add typing.NoReturn
  type, use WrapperDescriptorType, minor bug-fixes.  Original PRs by
  Jim Fasarakis-Hilliard and Ivan Levkivskyi.

* bpo-30205: Fix getsockname() for unbound AF_UNIX sockets on Linux.

* bpo-30070: Fixed leaks and crashes in errors handling in the parser
  module.

* bpo-30061: Fixed crashes in IOBase methods __next__() and
  readlines() when readline() or __next__() respectively return non-
  sizeable object. Fixed possible other errors caused by not checking
  results of PyObject_Size(), PySequence_Size(), or PyMapping_Size().

* bpo-30068: _io._IOBase.readlines will check if it’s closed first
  when hint is present.

* bpo-29694: Fixed race condition in pathlib mkdir with flags
  parents=True. Patch by Armin Rigo.

* bpo-29692: Fixed arbitrary unchaining of RuntimeError exceptions in
  contextlib.contextmanager.  Patch by Siddharth Velankar.

* bpo-29998: Pickling and copying ImportError now preserves name and
  path attributes.

* bpo-29942: Fix a crash in itertools.chain.from_iterable when
  encountering long runs of empty iterables.

* bpo-27863: Fixed multiple crashes in ElementTree caused by race
  conditions and wrong types.

* bpo-28699: Fixed a bug in pools in multiprocessing.pool that raising
  an exception at the very first of an iterable may swallow the
  exception or make the program hang. Patch by Davin Potts and Xiang
  Zhang.

* bpo-25803: Avoid incorrect errors raised by
  Path.mkdir(exist_ok=True) when the OS gives priority to errors such
  as EACCES over EEXIST.

* bpo-29861: Release references to tasks, their arguments and their
  results as soon as they are finished in multiprocessing.Pool.

* bpo-29884: faulthandler: Restore the old sigaltstack during
  teardown. Patch by Christophe Zeitouny.

* bpo-25455: Fixed crashes in repr of recursive buffered file-like
  objects.

* bpo-29800: Fix crashes in partial.__repr__ if the keys of
  partial.keywords are not strings.  Patch by Michael Seifert.

* bpo-29742: get_extra_info() raises exception if get called on closed
  ssl transport. Patch by Nikolay Kim.

* bpo-8256: Fixed possible failing or crashing input() if attributes
  “encoding” or “errors” of sys.stdin or sys.stdout are not set or are
  not strings.

* bpo-28298: Fix a bug that prevented array ‘Q’, ‘L’ and ‘I’ from
  accepting big intables (objects that have __int__) as elements.
  Patch by Oren Milman.

* bpo-29615: SimpleXMLRPCDispatcher no longer chains KeyError (or any
  other exception) to exception(s) raised in the dispatched methods.
  Patch by Petr Motejlek.

* bpo-29704: asyncio.subprocess.SubprocessStreamProtocol no longer
  closes before all pipes are closed.

* bpo-29703: Fix asyncio to support instantiation of new event loops
  in child processes.

* bpo-29376: Fix assertion error in threading._DummyThread.is_alive().

* bpo-29110: Fix file object leak in aifc.open() when file is given as
  a filesystem path and is not in valid AIFF format. Patch by Anthony
  Zhang.

* bpo-28961: Fix unittest.mock._Call helper: don’t ignore the name
  parameter anymore. Patch written by Jiajun Huang.

* bpo-29532: Altering a kwarg dictionary passed to functools.partial()
  no longer affects a partial object after creation.

* bpo-28556: Various updates to typing module: typing.Counter,
  typing.ChainMap, improved ABC caching, etc. Original PRs by Jelle
  Zijlstra, Ivan Levkivskyi, Manuel Krebber, and Łukasz Langa.

* bpo-29100: Fix datetime.fromtimestamp() regression introduced in
  Python 3.6.0: check minimum and maximum years.

* bpo-29519: Fix weakref spewing exceptions during interpreter
  shutdown when used with a rare combination of multiprocessing and
  custom codecs.

* bpo-29416: Prevent infinite loop in pathlib.Path.mkdir

* bpo-29444: Fixed out-of-bounds buffer access in the group() method
  of the match object. Based on patch by WGH.

* bpo-29335: Fix subprocess.Popen.wait() when the child process has
  exited to a stopped instead of terminated state (ex: when under
  ptrace).

* bpo-29290: Fix a regression in argparse that help messages would
  wrap at non-breaking spaces.

* bpo-28735: Fixed the comparison of mock.MagickMock with mock.ANY.

* bpo-29011: Fix an important omission by adding Deque to the typing
  module.

* bpo-29219: Fixed infinite recursion in the repr of uninitialized
  ctypes.CDLL instances.

* bpo-28969: Fixed race condition in C implementation of
  functools.lru_cache. KeyError could be raised when cached function
  with full cache was simultaneously called from different threads
  with the same uncached arguments.

* bpo-29142: In urllib.request, suffixes in no_proxy environment
  variable with leading dots could match related hostnames again (e.g.
  .b.c matches a.b.c). Patch by Milan Oberkirch.


Documentation
-------------

* bpo-30176: Add missing attribute related constants in curses
  documentation.

* bpo-26985: Add missing info of code object in inspect documentation.

* bpo-28929: Link the documentation to its source file on GitHub.

* bpo-25008: Document smtpd.py as effectively deprecated and add a
  pointer to aiosmtpd, a third-party asyncio-based replacement.

* bpo-26355: Add canonical header link on each page to corresponding
  major version of the documentation. Patch by Matthias Bussonnier.

* bpo-29349: Fix Python 2 syntax in code for building the
  documentation.


Tests
-----

* bpo-30822: Fix regrtest command line parser to allow passing -u
  extralargefile to run test_zipfile64.

* bpo-30383: regrtest: Enhance regrtest and backport features from the
  master branch. Add options: –coverage, –testdir, –list-tests (list
  test files, don’t run them), –list-cases (list test identifiers,
  don’t run them, bpo-30523), –matchfile (load a list of test filters
  from a text file, bpo-30540), –slowest (alias to –slow). Enhance
  output: add timestamp, test result, currently running tests, “Tests
  result: xxx” summary with total duration, etc. Fix reference leak
  hunting in regrtest, –huntrleaks: regrtest now warms up caches,
  create explicitly all internal singletons which are created on
  demand to prevent false positives when checking for reference leaks.
  (bpo-30675).

* bpo-30357: test_thread: setUp() now uses support.threading_setup()
  and support.threading_cleanup() to wait until threads complete to
  avoid random side effects on following tests. Initial patch written
  by Grzegorz Grzywacz.

* bpo-28087: Skip test_asyncore and test_eintr poll failures on macOS.
  Skip some tests of select.poll when running on macOS due to
  unresolved issues with the underlying system poll function on some
  macOS versions.

* bpo-30197: Enhanced functions swap_attr() and swap_item() in the
  test.support module. They now work when delete replaced attribute or
  item inside the with statement.  The old value of the attribute or
  item (or None if it doesn’t exist) now will be assigned to the
  target of the “as” clause, if there is one.

* bpo-29571: to match the behaviour of the "re.LOCALE" flag,
  test_re.test_locale_flag now uses
  "locale.getpreferredencoding(False)" to determine the candidate
  encoding for the test regex (allowing it to correctly skip the test
  when the default locale encoding is a multi-byte encoding)


Build
-----

* bpo-29243: Prevent unnecessary rebuilding of Python during "make
  test", "make install" and some other make targets when configured
  with "--enable-optimizations".

* bpo-23404: Don’t regenerate generated files based on file
  modification time anymore: the action is now explicit. Replace "make
  touch" with "make regen-all".

* bpo-29643: Fix "--enable-optimization" didn’t work.


Windows
-------

* bpo-30687: Locate msbuild.exe on Windows when building rather than
  vcvarsall.bat

* bpo-29392: Prevent crash when passing invalid arguments into msvcrt
  module.


C API
-----

* bpo-27867: Function PySlice_GetIndicesEx() is replaced with a macro
  if Py_LIMITED_API is set to the value between 0x03050400 and
  0x03060000 (not including) or 0x03060100 or higher.

* bpo-29083: Fixed the declaration of some public API functions.
  PyArg_VaParse() and PyArg_VaParseTupleAndKeywords() were not
  available in limited API. PyArg_ValidateKeywordArguments(),
  PyArg_UnpackTuple() and Py_BuildValue() were not available in
  limited API of version < 3.3 when PY_SSIZE_T_CLEAN is defined.


Python 3.5.3 final
==================

*Release date: 2017-01-17*

There were no code changes between 3.5.3rc1 and 3.5.3 final.


Python 3.5.3 release candidate 1
================================

*Release date: 2017-01-02*


Security
--------

* bpo-27278: Fix os.urandom() implementation using getrandom() on
  Linux. Truncate size to INT_MAX and loop until we collected enough
  random bytes, instead of casting a directly Py_ssize_t to int.

* bpo-22636: Avoid shell injection problems with
  ctypes.util.find_library().


Core and Builtins
-----------------

* bpo-29073: bytearray formatting no longer truncates on first null
  byte.

* bpo-28932: Do not include <sys/random.h> if it does not exist.

* bpo-28147: Fix a memory leak in split-table dictionaries: setattr()
  must not convert combined table into split table.

* bpo-25677: Correct the positioning of the syntax error caret for
  indented blocks. Based on patch by Michael Layzell.

* bpo-29000: Fixed bytes formatting of octals with zero padding in
  alternate form.

* bpo-28512: Fixed setting the offset attribute of SyntaxError by
  PyErr_SyntaxLocationEx() and PyErr_SyntaxLocationObject().

* bpo-28991: functools.lru_cache() was susceptible to an obscure
  reentrancy bug caused by a monkey-patched len() function.

* bpo-28648: Fixed crash in Py_DecodeLocale() in debug build on Mac OS
  X when decode astral characters.  Patch by Xiang Zhang.

* bpo-19398: Extra slash no longer added to sys.path components in
  case of empty compile-time PYTHONPATH components.

* bpo-28426: Fixed potential crash in PyUnicode_AsDecodedObject() in
  debug build.

* bpo-23782: Fixed possible memory leak in _PyTraceback_Add() and
  exception loss in PyTraceBack_Here().

* bpo-28379: Added sanity checks and tests for
  PyUnicode_CopyCharacters(). Patch by Xiang Zhang.

* bpo-28376: The type of long range iterator is now registered as
  Iterator. Patch by Oren Milman.

* bpo-28376: The constructor of range_iterator now checks that step is
  not 0. Patch by Oren Milman.

* bpo-26906: Resolving special methods of uninitialized type now
  causes implicit initialization of the type instead of a fail.

* bpo-18287: PyType_Ready() now checks that tp_name is not NULL.
  Original patch by Niklas Koep.

* bpo-24098: Fixed possible crash when AST is changed in process of
  compiling it.

* bpo-28350: String constants with null character no longer interned.

* bpo-26617: Fix crash when GC runs during weakref callbacks.

* bpo-27942: String constants now interned recursively in tuples and
  frozensets.

* bpo-21578: Fixed misleading error message when ImportError called
  with invalid keyword args.

* bpo-28203: Fix incorrect type in error message from "complex(1.0,
  {2:3})". Patch by Soumya Sharma.

* bpo-27955: Fallback on reading /dev/urandom device when the
  getrandom() syscall fails with EPERM, for example when blocked by
  SECCOMP.

* bpo-28131: Fix a regression in zipimport’s compile_source().
  zipimport should use the same optimization level as the interpreter.

* bpo-25221: Fix corrupted result from PyLong_FromLong(0) when Python
  is compiled with NSMALLPOSINTS = 0.

* bpo-25758: Prevents zipimport from unnecessarily encoding a filename
  (patch by Eryk Sun)

* bpo-28189: dictitems_contains no longer swallows compare errors.
  (Patch by Xiang Zhang)

* bpo-27812: Properly clear out a generator’s frame’s backreference to
  the generator to prevent crashes in frame.clear().

* bpo-27811: Fix a crash when a coroutine that has not been awaited is
  finalized with warnings-as-errors enabled.

* bpo-27587: Fix another issue found by PVS-Studio: Null pointer check
  after use of ‘def’ in _PyState_AddModule(). Initial patch by
  Christian Heimes.

* bpo-26020: set literal evaluation order did not match documented
  behaviour.

* bpo-27782: Multi-phase extension module import now correctly allows
  the "m_methods" field to be used to add module level functions to
  instances of non-module types returned from "Py_create_mod". Patch
  by Xiang Zhang.

* bpo-27936: The round() function accepted a second None argument for
  some types but not for others.  Fixed the inconsistency by accepting
  None for all numeric types.

* bpo-27487: Warn if a submodule argument to “python -m” or
  runpy.run_module() is found in sys.modules after parent packages are
  imported, but before the submodule is executed.

* bpo-27558: Fix a SystemError in the implementation of “raise”
  statement. In a brand new thread, raise a RuntimeError since there
  is no active exception to reraise. Patch written by Xiang Zhang.

* bpo-27419: Standard __import__() no longer look up “__import__” in
  globals or builtins for importing submodules or “from import”.
  Fixed handling an error of non-string package name.

* bpo-27083: Respect the PYTHONCASEOK environment variable under
  Windows.

* bpo-27514: Make having too many statically nested blocks a
  SyntaxError instead of SystemError.

* bpo-27473: Fixed possible integer overflow in bytes and bytearray
  concatenations. Patch by Xiang Zhang.

* bpo-27507: Add integer overflow check in bytearray.extend().  Patch
  by Xiang Zhang.

* bpo-27581: Don’t rely on wrapping for overflow check in
  PySequence_Tuple().  Patch by Xiang Zhang.

* bpo-27443: __length_hint__() of bytearray iterators no longer return
  a negative integer for a resized bytearray.

* bpo-27942: Fix memory leak in codeobject.c


Library
-------

* bpo-15812: inspect.getframeinfo() now correctly shows the first line
  of a context. Patch by Sam Breese.

* bpo-29094: Offsets in a ZIP file created with extern file object and
  modes “w” and “x” now are relative to the start of the file.

* bpo-13051: Fixed recursion errors in large or resized
  curses.textpad.Textbox.  Based on patch by Tycho Andersen.

* bpo-29119: Fix weakrefs in the pure python version of
  collections.OrderedDict move_to_end() method. Contributed by Andra
  Bogildea.

* bpo-9770: curses.ascii predicates now work correctly with negative
  integers.

* bpo-28427: old keys should not remove new values from
  WeakValueDictionary when collecting from another thread.

* bpo-28923: Remove editor artifacts from Tix.py.

* bpo-28871: Fixed a crash when deallocate deep ElementTree.

* bpo-19542: Fix bugs in WeakValueDictionary.setdefault() and
  WeakValueDictionary.pop() when a GC collection happens in another
  thread.

* bpo-20191: Fixed a crash in resource.prlimit() when pass a sequence
  that doesn’t own its elements as limits.

* bpo-28779: multiprocessing.set_forkserver_preload() would crash the
  forkserver process if a preloaded module instantiated some
  multiprocessing objects such as locks.

* bpo-28847: dbm.dumb now supports reading read-only files and no
  longer writes the index file when it is not changed.

* bpo-25659: In ctypes, prevent a crash calling the from_buffer() and
  from_buffer_copy() methods on abstract classes like Array.

* bpo-28732: Fix crash in os.spawnv() with no elements in args

* bpo-28485: Always raise ValueError for negative
  compileall.compile_dir(workers=…) parameter, even when
  multithreading is unavailable.

* bpo-28387: Fixed possible crash in _io.TextIOWrapper deallocator
  when the garbage collector is invoked in other thread.  Based on
  patch by Sebastian Cufre.

* bpo-27517: LZMA compressor and decompressor no longer raise
  exceptions if given empty data twice.  Patch by Benjamin Fogle.

* bpo-28549: Fixed segfault in curses’s addch() with ncurses6.

* bpo-28449: tarfile.open() with mode “r” or “r:” now tries to open a
  tar file with compression before trying to open it without
  compression. Otherwise it had 50% chance failed with
  ignore_zeros=True.

* bpo-23262: The webbrowser module now supports Firefox 36+ and
  derived browsers.  Based on patch by Oleg Broytman.

* bpo-27939: Fixed bugs in tkinter.ttk.LabeledScale and tkinter.Scale
  caused by representing the scale as float value internally in Tk.
  tkinter.IntVar now works if float value is set to underlying Tk
  variable.

* bpo-28255: calendar.TextCalendar().prmonth() no longer prints a
  space at the start of new line after printing a month’s calendar.
  Patch by Xiang Zhang.

* bpo-20491: The textwrap.TextWrapper class now honors non-breaking
  spaces. Based on patch by Kaarle Ritvanen.

* bpo-28353: os.fwalk() no longer fails on broken links.

* bpo-25464: Fixed HList.header_exists() in tkinter.tix module by
  addin a workaround to Tix library bug.

* bpo-28488: shutil.make_archive() no longer add entry “./” to ZIP
  archive.

* bpo-24452: Make webbrowser support Chrome on Mac OS X.

* bpo-20766: Fix references leaked by pdb in the handling of SIGINT
  handlers.

* bpo-26293: Fixed writing ZIP files that starts not from the start of
  the file.  Offsets in ZIP file now are relative to the start of the
  archive in conforming to the specification.

* bpo-28321: Fixed writing non-BMP characters with binary format in
  plistlib.

* bpo-28322: Fixed possible crashes when unpickle itertools objects
  from incorrect pickle data.  Based on patch by John Leitch.

* Fix possible integer overflows and crashes in the mmap module with
  unusual usage patterns.

* bpo-1703178: Fix the ability to pass the –link-objects option to the
  distutils build_ext command.

* bpo-28253: Fixed calendar functions for extreme months: 0001-01 and
  9999-12. Methods itermonthdays() and itermonthdays2() are
  reimplemented so that they don’t call itermonthdates() which can
  cause datetime.date under/overflow.

* bpo-28275: Fixed possible use after free in the decompress() methods
  of the LZMADecompressor and BZ2Decompressor classes. Original patch
  by John Leitch.

* bpo-27897: Fixed possible crash in
  sqlite3.Connection.create_collation() if pass invalid string-like
  object as a name.  Patch by Xiang Zhang.

* bpo-18893: Fix invalid exception handling in
  Lib/ctypes/macholib/dyld.py. Patch by Madison May.

* bpo-27611: Fixed support of default root window in the tkinter.tix
  module.

* bpo-27348: In the traceback module, restore the formatting of
  exception messages like “Exception: None”.  This fixes a regression
  introduced in 3.5a2.

* bpo-25651: Allow falsy values to be used for msg parameter of
  subTest().

* bpo-27932: Prevent memory leak in win32_ver().

* Fix UnboundLocalError in socket._sendfile_use_sendfile.

* bpo-28075: Check for ERROR_ACCESS_DENIED in Windows implementation
  of os.stat().  Patch by Eryk Sun.

* bpo-25270: Prevent codecs.escape_encode() from raising SystemError
  when an empty bytestring is passed.

* bpo-28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.

* bpo-25895: Enable WebSocket URL schemes in urllib.parse.urljoin.
  Patch by Gergely Imreh and Markus Holtermann.

* bpo-27599: Fixed buffer overrun in binascii.b2a_qp() and
  binascii.a2b_qp().

* bpo-19003: m email.generator now replaces only "\r" and/or "\n" line
  endings, per the RFC, instead of all unicode line endings.

* bpo-28019: itertools.count() no longer rounds non-integer step in
  range between 1.0 and 2.0 to 1.

* bpo-25969: Update the lib2to3 grammar to handle the unpacking
  generalizations added in 3.5.

* bpo-14977: mailcap now respects the order of the lines in the
  mailcap files (“first match”), as required by RFC 1542.  Patch by
  Michael Lazar.

* bpo-24594: Validates persist parameter when opening MSI database

* bpo-17582: xml.etree.ElementTree nows preserves whitespaces in
  attributes (Patch by Duane Griffin.  Reviewed and approved by Stefan
  Behnel.)

* bpo-28047: Fixed calculation of line length used for the base64 CTE
  in the new email policies.

* bpo-27445: Don’t pass str(_charset) to MIMEText.set_payload(). Patch
  by Claude Paroz.

* bpo-22450: urllib now includes an "Accept: */*" header among the
  default headers. This makes the results of REST API requests more
  consistent and predictable especially when proxy servers are
  involved.

* lib2to3.pgen3.driver.load_grammar() now creates a stable cache file
  between runs given the same Grammar.txt input regardless of the hash
  randomization setting.

* bpo-27570: Avoid zero-length memcpy() etc calls with null source
  pointers in the “ctypes” and “array” modules.

* bpo-22233: Break email header lines *only* on the RFC specified CR
  and LF characters, not on arbitrary unicode line breaks.  This also
  fixes a bug in HTTP header parsing.

* bpo-27988: Fix email iter_attachments incorrect mutation of payload
  list.

* bpo-27691: Fix ssl module’s parsing of GEN_RID subject alternative
  name fields in X.509 certs.

* bpo-27850: Remove 3DES from ssl module’s default cipher list to
  counter measure sweet32 attack (CVE-2016-2183).

* bpo-27766: Add ChaCha20 Poly1305 to ssl module’s default cipher
  list. (Required OpenSSL 1.1.0 or LibreSSL).

* bpo-26470: Port ssl and hashlib module to OpenSSL 1.1.0.

* Remove support for passing a file descriptor to os.access. It never
  worked but previously didn’t raise.

* bpo-12885: Fix error when distutils encounters symlink.

* bpo-27881: Fixed possible bugs when setting
  sqlite3.Connection.isolation_level. Based on patch by Xiang Zhang.

* bpo-27861: Fixed a crash in sqlite3.Connection.cursor() when a
  factory creates not a cursor.  Patch by Xiang Zhang.

* bpo-19884: Avoid spurious output on OS X with Gnu Readline.

* bpo-27706: Restore deterministic behavior of random.Random().seed()
  for string seeds using seeding version 1.  Allows sequences of calls
  to random() to exactly match those obtained in Python 2. Patch by
  Nofar Schnider.

* bpo-10513: Fix a regression in Connection.commit().  Statements
  should not be reset after a commit.

* A new version of typing.py from https://github.com/python/typing:
  Collection (only for 3.6) (bpo-27598). Add FrozenSet to __all__
  (upstream #261). Fix crash in _get_type_vars() (upstream #259).
  Remove the dict constraint in ForwardRef._eval_type (upstream #252).

* bpo-27539: Fix unnormalised "Fraction.__pow__" result in the case of
  negative exponent and negative base.

* bpo-21718: cursor.description is now available for queries using
  CTEs.

* bpo-2466: posixpath.ismount now correctly recognizes mount points
  which the user does not have permission to access.

* bpo-27773: Correct some memory management errors server_hostname in
  _ssl.wrap_socket().

* bpo-26750: unittest.mock.create_autospec() now works properly for
  subclasses of property() and other data descriptors.

* In the curses module, raise an error if window.getstr() or
  window.instr() is passed a negative value.

* bpo-27783: Fix possible usage of uninitialized memory in
  operator.methodcaller.

* bpo-27774: Fix possible Py_DECREF on unowned object in _sre.

* bpo-27760: Fix possible integer overflow in binascii.b2a_qp.

* bpo-27758: Fix possible integer overflow in the _csv module for
  large record lengths.

* bpo-27568: Prevent HTTPoxy attack (CVE-2016-1000110). Ignore the
  HTTP_PROXY variable when REQUEST_METHOD environment is set, which
  indicates that the script is in CGI mode.

* bpo-27656: Do not assume sched.h defines any SCHED_* constants.

* bpo-27130: In the “zlib” module, fix handling of large buffers
  (typically 4 GiB) when compressing and decompressing.  Previously,
  inputs were limited to 4 GiB, and compression and decompression
  operations did not properly handle results of 4 GiB.

* bpo-27533: Release GIL in nt._isdir

* bpo-17711: Fixed unpickling by the persistent ID with protocol 0.
  Original patch by Alexandre Vassalotti.

* bpo-27522: Avoid an unintentional reference cycle in
  email.feedparser.

* bpo-26844: Fix error message for imp.find_module() to refer to
  ‘path’ instead of ‘name’. Patch by Lev Maximov.

* bpo-23804: Fix SSL zero-length recv() calls to not block and not
  raise an error about unclean EOF.

* bpo-27466: Change time format returned by http.cookie.time2netscape,
  confirming the netscape cookie format and making it consistent with
  documentation.

* bpo-26664: Fix activate.fish by removing mis-use of "$".

* bpo-22115: Fixed tracing Tkinter variables: trace_vdelete() with
  wrong mode no longer break tracing, trace_vinfo() now always returns
  a list of pairs of strings, tracing in the “u” mode now works.

* Fix a scoping issue in importlib.util.LazyLoader which triggered an
  UnboundLocalError when lazy-loading a module that was already put
  into sys.modules.

* bpo-27079: Fixed curses.ascii functions isblank(), iscntrl() and
  ispunct().

* bpo-26754: Some functions (compile() etc) accepted a filename
  argument encoded as an iterable of integers. Now only strings and
  byte-like objects are accepted.

* bpo-27048: Prevents distutils failing on Windows when environment
  variables contain non-ASCII characters

* bpo-27330: Fixed possible leaks in the ctypes module.

* bpo-27238: Got rid of bare excepts in the turtle module.  Original
  patch by Jelle Zijlstra.

* bpo-27122: When an exception is raised within the context being
  managed by a contextlib.ExitStack() and one of the exit stack
  generators catches and raises it in a chain, do not re-raise the
  original exception when exiting, let the new chained one through.
  This avoids the **PEP 479** bug described in issue25782.

* bpo-26386: Fixed ttk.TreeView selection operations with item id’s
  containing spaces.

* bpo-16182: Fix various functions in the “readline” module to use the
  locale encoding, and fix get_begidx() and get_endidx() to return
  code point indexes.

* bpo-27392: Add loop.connect_accepted_socket(). Patch by Jim Fulton.

* bpo-27930: Improved behaviour of logging.handlers.QueueListener.
  Thanks to Paulo Andrade and Petr Viktorin for the analysis and
  patch.

* bpo-21201: Improves readability of multiprocessing error message.
  Thanks to Wojciech Walczak for patch.

* bpo-27456: asyncio: Set TCP_NODELAY by default.

* bpo-27906: Fix socket accept exhaustion during high TCP traffic.
  Patch by Kevin Conway.

* bpo-28174: Handle when SO_REUSEPORT isn’t properly supported. Patch
  by Seth Michael Larson.

* bpo-26654: Inspect functools.partial in asyncio.Handle.__repr__.
  Patch by iceboy.

* bpo-26909: Fix slow pipes IO in asyncio. Patch by INADA Naoki.

* bpo-28176: Fix callbacks race in asyncio.SelectorLoop.sock_connect.

* bpo-27759: Fix selectors incorrectly retain invalid file
  descriptors. Patch by Mark Williams.

* bpo-28368: Refuse monitoring processes if the child watcher has no
  loop attached. Patch by Vincent Michel.

* bpo-28369: Raise RuntimeError when transport’s FD is used with
  add_reader, add_writer, etc.

* bpo-28370: Speedup asyncio.StreamReader.readexactly. Patch by
  Коренберг Марк.

* bpo-28371: Deprecate passing asyncio.Handles to run_in_executor.

* bpo-28372: Fix asyncio to support formatting of non-python
  coroutines.

* bpo-28399: Remove UNIX socket from FS before binding. Patch by
  Коренберг Марк.

* bpo-27972: Prohibit Tasks to await on themselves.

* bpo-26923: Fix asyncio.Gather to refuse being cancelled once all
  children are done. Patch by Johannes Ebke.

* bpo-26796: Don’t configure the number of workers for default
  threadpool executor. Initial patch by Hans Lawrenz.

* bpo-28600: Optimize loop.call_soon().

* bpo-28613: Fix get_event_loop() return the current loop if called
  from coroutines/callbacks.

* bpo-28639: Fix inspect.isawaitable to always return bool Patch by
  Justin Mayfield.

* bpo-28652: Make loop methods reject socket kinds they do not
  support.

* bpo-28653: Fix a refleak in functools.lru_cache.

* bpo-28703: Fix asyncio.iscoroutinefunction to handle Mock objects.

* bpo-24142: Reading a corrupt config file left the parser in an
  invalid state.  Original patch by Florian Höch.

* bpo-28990: Fix SSL hanging if connection is closed before handshake
  completed. (Patch by HoHo-Ho)


IDLE
----

* bpo-15308: Add ‘interrupt execution’ (^C) to Shell menu. Patch by
  Roger Serwy, updated by Bayard Randel.

* bpo-27922: Stop IDLE tests from ‘flashing’ gui widgets on the
  screen.

* Add version to title of IDLE help window.

* bpo-25564: In section on IDLE – console differences, mention that
  using exec means that __builtins__ is defined for each statement.

* bpo-27714: text_textview and test_autocomplete now pass when re-run
  in the same process.  This occurs when test_idle fails when run with
  the -w option but without -jn.  Fix warning from test_config.

* bpo-25507: IDLE no longer runs buggy code because of its tkinter
  imports. Users must include the same imports required to run
  directly in Python.

* bpo-27452: add line counter and crc to IDLE configHandler test dump.

* bpo-27365: Allow non-ascii chars in IDLE NEWS.txt, for contributor
  names.

* bpo-27245: IDLE: Cleanly delete custom themes and key bindings.
  Previously, when IDLE was started from a console or by import, a
  cascade of warnings was emitted. Patch by Serhiy Storchaka.


C API
-----

* bpo-28808: PyUnicode_CompareWithASCIIString() now never raises
  exceptions.

* bpo-26754: PyUnicode_FSDecoder() accepted a filename argument
  encoded as an iterable of integers. Now only strings and bytes-like
  objects are accepted.


Documentation
-------------

* bpo-28513: Documented command-line interface of zipfile.


Tests
-----

* bpo-28950: Disallow -j0 to be combined with -T/-l/-M in regrtest
  command line arguments.

* bpo-28666: Now test.support.rmtree is able to remove unwritable or
  unreadable directories.

* bpo-23839: Various caches now are cleared before running every test
  file.

* bpo-28409: regrtest: fix the parser of command line arguments.

* bpo-27787: Call gc.collect() before checking each test for “dangling
  threads”, since the dangling threads are weak references.

* bpo-27369: In test_pyexpat, avoid testing an error message detail
  that changed in Expat 2.2.0.


Tools/Demos
-----------

* bpo-27952: Get Tools/scripts/fixcid.py working with Python 3 and the
  current “re” module, avoid invalid Python backslash escapes, and fix
  a bug parsing escaped C quote signs.

* bpo-27332: Fixed the type of the first argument of module-level
  functions generated by Argument Clinic.  Patch by Petr Viktorin.

* bpo-27418: Fixed Tools/importbench/importbench.py.


Windows
-------

* bpo-28251: Improvements to help manuals on Windows.

* bpo-28110: launcher.msi has different product codes between 32-bit
  and 64-bit

* bpo-25144: Ensures TargetDir is set before continuing with custom
  install.

* bpo-27469: Adds a shell extension to the launcher so that drag and
  drop works correctly.

* bpo-27309: Enabled proper Windows styles in python[w].exe manifest.


Build
-----

* bpo-29080: Removes hard dependency on hg.exe from PCBuild/build.bat

* bpo-23903: Added missed names to PC/python3.def.

* bpo-10656: Fix out-of-tree building on AIX.  Patch by Tristan Carel
  and Michael Haubenwallner.

* bpo-26359: Rename –with-optimiations to –enable-optimizations.

* bpo-28444: Fix missing extensions modules when cross compiling.

* bpo-28248: Update Windows build and OS X installers to use OpenSSL
  1.0.2j.

* bpo-28258: Fixed build with Estonian locale (python-config and
  distclean targets in Makefile).  Patch by Arfrever Frehtes Taifersar
  Arahesis.

* bpo-26661: setup.py now detects system libffi with multiarch
  wrapper.

* bpo-28066: Fix the logic that searches build directories for
  generated include files when building outside the source tree.

* bpo-15819: Remove redundant include search directory option for
  building outside the source tree.

* bpo-27566: Fix clean target in freeze makefile (patch by Lisa Roach)

* bpo-27705: Update message in validate_ucrtbase.py

* bpo-27983: Cause lack of llvm-profdata tool when using clang as
  required for PGO linking to be a configure time error rather than
  make time when –with-optimizations is enabled.  Also improve our
  ability to find the llvm-profdata tool on MacOS and some Linuxes.

* bpo-26307: The profile-opt build now applies PGO to the built-in
  modules.

* bpo-26359: Add the –with-optimizations configure flag.

* bpo-27713: Suppress spurious build warnings when updating
  importlib’s bootstrap files. Patch by Xiang Zhang

* bpo-25825: Correct the references to Modules/python.exp and
  ld_so_aix, which are required on AIX.  This updates references to an
  installation path that was changed in 3.2a4, and undoes changed
  references to the build tree that were made in 3.5.0a1.

* bpo-27453: CPP invocation in configure must use CPPFLAGS. Patch by
  Chi Hsuan Yen.

* bpo-27641: The configure script now inserts comments into the
  makefile to prevent the pgen and _freeze_importlib executables from
  being cross-compiled.

* bpo-26662: Set PYTHON_FOR_GEN in configure as the Python program to
  be used for file generation during the build.

* bpo-10910: Avoid C++ compilation errors on FreeBSD and OS X. Also
  update FreedBSD version checks for the original ctype UTF-8
  workaround.

* bpo-28676: Prevent missing ‘getentropy’ declaration warning on
  macOS. Patch by Gareth Rees.


Python 3.5.2 final
==================

*Release date: 2016-06-26*


Core and Builtins
-----------------

* bpo-26930: Update Windows builds to use OpenSSL 1.0.2h.


Tests
-----

* bpo-26867: Ubuntu’s openssl OP_NO_SSLv3 is forced on by default; fix
  test.


IDLE
----

* bpo-27365: Allow non-ascii in idlelib/NEWS.txt - minimal part for
  3.5.2.


Python 3.5.2 release candidate 1
================================

*Release date: 2016-06-12*


Security
--------

* bpo-26556: Update expat to 2.1.1, fixes CVE-2015-1283.

* Fix TLS stripping vulnerability in smtplib, CVE-2016-0772. Reported
  by Team Oststrom

* bpo-26839: On Linux, "os.urandom()" now calls "getrandom()" with
  "GRND_NONBLOCK" to fall back on reading "/dev/urandom" if the
  urandom entropy pool is not initialized yet. Patch written by Colm
  Buckley.

* bpo-26657: Fix directory traversal vulnerability with http.server on
  Windows.  This fixes a regression that was introduced in 3.3.4rc1
  and 3.4.0rc1.  Based on patch by Philipp Hagemeister.

* bpo-26313: ssl.py _load_windows_store_certs fails if windows cert
  store is empty. Patch by Baji.

* bpo-25939: On Windows open the cert store readonly in
  ssl.enum_certificates.


Core and Builtins
-----------------

* bpo-27066: Fixed SystemError if a custom opener (for open()) returns
  a negative number without setting an exception.

* bpo-20041: Fixed TypeError when frame.f_trace is set to None. Patch
  by Xavier de Gaye.

* bpo-26168: Fixed possible refleaks in failing Py_BuildValue() with
  the “N” format unit.

* bpo-26991: Fix possible refleak when creating a function with
  annotations.

* bpo-27039: Fixed bytearray.remove() for values greater than 127.
  Patch by Joe Jevnik.

* bpo-23640: int.from_bytes() no longer bypasses constructors for
  subclasses.

* bpo-26811: gc.get_objects() no longer contains a broken tuple with
  NULL pointer.

* bpo-20120: Use RawConfigParser for .pypirc parsing, removing support
  for interpolation unintentionally added with move to Python 3.
  Behavior no longer does any interpolation in .pypirc files, matching
  behavior in Python 2.7 and Setuptools 19.0.

* bpo-26659: Make the builtin slice type support cycle collection.

* bpo-26718: super.__init__ no longer leaks memory if called multiple
  times. NOTE: A direct call of super.__init__ is not endorsed!

* bpo-25339: PYTHONIOENCODING now has priority over locale in setting
  the error handler for stdin and stdout.

* bpo-26494: Fixed crash on iterating exhausting iterators. Affected
  classes are generic sequence iterators, iterators of str, bytes,
  bytearray, list, tuple, set, frozenset, dict, OrderedDict,
  corresponding views and os.scandir() iterator.

* bpo-26581: If coding cookie is specified multiple times on a line in
  Python source code file, only the first one is taken to account.

* bpo-26464: Fix str.translate() when string is ASCII and first
  replacements removes character, but next replacement uses a non-
  ASCII character or a string longer than 1 character. Regression
  introduced in Python 3.5.0.

* bpo-22836: Ensure exception reports from PyErr_Display() and
  PyErr_WriteUnraisable() are sensible even when formatting them
  produces secondary errors.  This affects the reports produced by
  sys.__excepthook__() and when __del__() raises an exception.

* bpo-26302: Correct behavior to reject comma as a legal character for
  cookie names.

* bpo-4806: Avoid masking the original TypeError exception when using
  star ("*") unpacking in function calls.  Based on patch by Hagen
  Fürstenau and Daniel Urban.

* bpo-27138: Fix the doc comment for FileFinder.find_spec().

* bpo-26154: Add a new private _PyThreadState_UncheckedGet() function
  to get the current Python thread state, but don’t issue a fatal
  error if it is NULL. This new function must be used instead of
  accessing directly the _PyThreadState_Current variable.  The
  variable is no more exposed since Python 3.5.1 to hide the exact
  implementation of atomic C types, to avoid compiler issues.

* bpo-26194: Deque.insert() gave odd results for bounded deques that
  had reached their maximum size.  Now an IndexError will be raised
  when attempting to insert into a full deque.

* bpo-25843: When compiling code, don’t merge constants if they are
  equal but have a different types. For example, "f1, f2 = lambda: 1,
  lambda: 1.0" is now correctly compiled to two different functions:
  "f1()" returns "1" ("int") and "f2()" returns "1.0" ("int"), even if
  "1" and "1.0" are equal.

* bpo-22995: [UPDATE] Comment out the one of the pickleability tests
  in _PyObject_GetState() due to regressions observed in Cython-based
  projects.

* bpo-25961: Disallowed null characters in the type name.

* bpo-25973: Fix segfault when an invalid nonlocal statement binds a
  name starting with two underscores.

* bpo-22995: Instances of extension types with a state that aren’t
  subclasses of list or dict and haven’t implemented any pickle-
  related methods (__reduce__, __reduce_ex__, __getnewargs__,
  __getnewargs_ex__, or __getstate__), can no longer be pickled.
  Including memoryview.

* bpo-20440: Massive replacing unsafe attribute setting code with
  special macro Py_SETREF.

* bpo-25766: Special method __bytes__() now works in str subclasses.

* bpo-25421: __sizeof__ methods of builtin types now use dynamic basic
  size. This allows sys.getsize() to work correctly with their
  subclasses with __slots__ defined.

* bpo-25709: Fixed problem with in-place string concatenation and
  utf-8 cache.

* bpo-27147: Mention **PEP 420** in the importlib docs.

* bpo-24097: Fixed crash in object.__reduce__() if slot name is freed
  inside __getattr__.

* bpo-24731: Fixed crash on converting objects with special methods
  __bytes__, __trunc__, and __float__ returning instances of
  subclasses of bytes, int, and float to subclasses of bytes, int, and
  float correspondingly.

* bpo-26478: Fix semantic bugs when using binary operators with
  dictionary views and tuples.

* bpo-26171: Fix possible integer overflow and heap corruption in
  zipimporter.get_data().

* bpo-25660: Fix TAB key behaviour in REPL with readline.

* bpo-25887: Raise a RuntimeError when a coroutine object is awaited
  more than once.

* bpo-27243: Update the __aiter__ protocol: instead of returning an
  awaitable that resolves to an asynchronous iterator, the
  asynchronous iterator should be returned directly.  Doing the former
  will trigger a PendingDeprecationWarning.


Library
-------

* bpo-21386: Implement missing IPv4Address.is_global property.  It was
  documented since 07a5610bae9d.  Initial patch by Roger Luethi.

* bpo-20900: distutils register command now decodes HTTP responses
  correctly.  Initial patch by ingrid.

* A new version of typing.py provides several new classes and
  features: @overload outside stubs, Reversible, DefaultDict, Text,
  ContextManager, Type[], NewType(), TYPE_CHECKING, and numerous bug
  fixes (note that some of the new features are not yet implemented in
  mypy or other static analyzers). Also classes for **PEP 492**
  (Awaitable, AsyncIterable, AsyncIterator) have been added (in fact
  they made it into 3.5.1 but were never mentioned).

* bpo-25738: Stop http.server.BaseHTTPRequestHandler.send_error() from
  sending a message body for 205 Reset Content.  Also, don’t send
  Content header fields in responses that don’t have a body.  Patch by
  Susumu Koshiba.

* bpo-21313: Fix the “platform” module to tolerate when sys.version
  contains truncated build information.

* bpo-27164: In the zlib module, allow decompressing raw Deflate
  streams with a predefined zdict.  Based on patch by Xiang Zhang.

* bpo-24291: Fix wsgiref.simple_server.WSGIRequestHandler to
  completely write data to the client.  Previously it could do partial
  writes and truncate data.  Also, wsgiref.handler.ServerHandler can
  now handle stdout doing partial writes, but this is deprecated.

* bpo-26809: Add "__all__" to "string".  Patch by Emanuel Barry.

* bpo-26373: subprocess.Popen.communicate now correctly ignores
  BrokenPipeError when the child process dies before .communicate() is
  called in more/all circumstances.

* bpo-21776: distutils.upload now correctly handles HTTPError. Initial
  patch by Claudiu Popa.

* bpo-27114: Fix SSLContext._load_windows_store_certs fails with
  PermissionError

* bpo-18383: Avoid creating duplicate filters when using
  filterwarnings and simplefilter. Based on patch by Alex Shkop.

* bpo-27057: Fix os.set_inheritable() on Android, ioctl() is blocked
  by SELinux and fails with EACCESS. The function now falls back to
  fcntl(). Patch written by Michał Bednarski.

* bpo-27014: Fix infinite recursion using typing.py.  Thanks to Kalle
  Tuure!

* bpo-14132: Fix urllib.request redirect handling when the target only
  has a query string.  Original fix by Ján Janech.

* bpo-17214: The “urllib.request” module now percent-encodes non-ASCII
  bytes found in redirect target URLs.  Some servers send Location
  header fields with non-ASCII bytes, but “http.client” requires the
  request target to be ASCII-encodable, otherwise a UnicodeEncodeError
  is raised.  Based on patch by Christian Heimes.

* bpo-26892: Honor debuglevel flag in urllib.request.HTTPHandler.
  Patch contributed by Chi Hsuan Yen.

* bpo-22274: In the subprocess module, allow stderr to be redirected
  to stdout even when stdout is not redirected.  Patch by Akira Li.

* bpo-26807: mock_open ‘files’ no longer error on readline at end of
  file. Patch from Yolanda Robla.

* bpo-25745: Fixed leaking a userptr in curses panel destructor.

* bpo-26977: Removed unnecessary, and ignored, call to sum of squares
  helper in statistics.pvariance.

* bpo-26881: The modulefinder module now supports extended opcode
  arguments.

* bpo-23815: Fixed crashes related to directly created instances of
  types in _tkinter and curses.panel modules.

* bpo-17765: weakref.ref() no longer silently ignores keyword
  arguments. Patch by Georg Brandl.

* bpo-26873: xmlrpc now raises ResponseError on unsupported type tags
  instead of silently return incorrect result.

* bpo-26711: Fixed the comparison of plistlib.Data with other types.

* bpo-24114: Fix an uninitialized variable in "ctypes.util". The bug
  only occurs on SunOS when the ctypes implementation searches for the
  "crle" program.  Patch by Xiang Zhang.  Tested on SunOS by Kees Bos.

* bpo-26864: In urllib.request, change the proxy bypass host checking
  against no_proxy to be case-insensitive, and to not match unrelated
  host names that happen to have a bypassed hostname as a suffix.
  Patch by Xiang Zhang.

* bpo-26634: recursive_repr() now sets __qualname__ of wrapper.  Patch
  by Xiang Zhang.

* bpo-26804: urllib.request will prefer lower_case proxy environment
  variables over UPPER_CASE or Mixed_Case ones. Patch contributed by
  Hans-Peter Jansen.

* bpo-26837: assertSequenceEqual() now correctly outputs non-
  stringified differing items (like bytes in the -b mode).  This
  affects assertListEqual() and assertTupleEqual().

* bpo-26041: Remove “will be removed in Python 3.7” from deprecation
  messages of platform.dist() and platform.linux_distribution(). Patch
  by Kumaripaba Miyurusara Athukorala.

* bpo-26822: itemgetter, attrgetter and methodcaller objects no longer
  silently ignore keyword arguments.

* bpo-26733: Disassembling a class now disassembles class and static
  methods. Patch by Xiang Zhang.

* bpo-26801: Fix error handling in "shutil.get_terminal_size()", catch
  "AttributeError" instead of "NameError". Patch written by Emanuel
  Barry.

* bpo-24838: tarfile’s ustar and gnu formats now correctly calculate
  name and link field limits for multibyte character encodings like
  utf-8.

* bpo-26717: Stop encoding Latin-1-ized WSGI paths with UTF-8.  Patch
  by Anthony Sottile.

* bpo-26735: Fix "os.urandom()" on Solaris 11.3 and newer when reading
  more than 1,024 bytes: call "getrandom()" multiple times with a
  limit of 1024 bytes per call.

* bpo-16329: Add .webm to mimetypes.types_map.  Patch by Giampaolo
  Rodola’.

* bpo-13952: Add .csv to mimetypes.types_map.  Patch by Geoff Wilson.

* bpo-26709: Fixed Y2038 problem in loading binary PLists.

* bpo-23735: Handle terminal resizing with Readline 6.3+ by installing
  our own SIGWINCH handler.  Patch by Eric Price.

* bpo-26586: In http.server, respond with “413 Request header fields
  too large” if there are too many header fields to parse, rather than
  killing the connection and raising an unhandled exception.  Patch by
  Xiang Zhang.

* bpo-22854: Change BufferedReader.writable() and
  BufferedWriter.readable() to always return False.

* bpo-25195: Fix a regression in mock.MagicMock. _Call is a subclass
  of tuple (changeset 3603bae63c13 only works for classes) so we need
  to implement __ne__ ourselves.  Patch by Andrew Plummer.

* bpo-26644: Raise ValueError rather than SystemError when a negative
  length is passed to SSLSocket.recv() or read().

* bpo-23804: Fix SSL recv(0) and read(0) methods to return zero bytes
  instead of up to 1024.

* bpo-26616: Fixed a bug in datetime.astimezone() method.

* bpo-21925: "warnings.formatwarning()" now catches exceptions on
  "linecache.getline(...)" to be able to log "ResourceWarning" emitted
  late during the Python shutdown process.

* bpo-24266: Ctrl+C during Readline history search now cancels the
  search mode when compiled with Readline 7.

* bpo-26560: Avoid potential ValueError in BaseHandler.start_response.
  Initial patch by Peter Inglesby.

* bpo-26569: Fix "pyclbr.readmodule()" and "pyclbr.readmodule_ex()" to
  support importing packages.

* bpo-26499: Account for remaining Content-Length in
  HTTPResponse.readline() and read1(). Based on patch by Silent Ghost.
  Also document that HTTPResponse now supports these methods.

* bpo-25320: Handle sockets in directories unittest discovery is
  scanning. Patch from Victor van den Elzen.

* bpo-16181: cookiejar.http2time() now returns None if year is higher
  than datetime.MAXYEAR.

* bpo-26513: Fixes platform module detection of Windows Server

* bpo-23718: Fixed parsing time in week 0 before Jan 1.  Original
  patch by Tamás Bence Gedai.

* bpo-20589: Invoking Path.owner() and Path.group() on Windows now
  raise NotImplementedError instead of ImportError.

* bpo-26177: Fixed the keys() method for Canvas and Scrollbar widgets.

* bpo-15068: Got rid of excessive buffering in the fileinput module.
  The bufsize parameter is no longer used.

* bpo-2202: Fix UnboundLocalError in
  AbstractDigestAuthHandler.get_algorithm_impls. Initial patch by
  Mathieu Dupuy.

* bpo-25718: Fixed pickling and copying the accumulate() iterator with
  total is None.

* bpo-26475: Fixed debugging output for regular expressions with the
  (?x) flag.

* bpo-26457: Fixed the subnets() methods in IP network classes for the
  case when resulting prefix length is equal to maximal prefix length.
  Based on patch by Xiang Zhang.

* bpo-26385: Remove the file if the internal open() call in
  NamedTemporaryFile() fails. Patch by Silent Ghost.

* bpo-26402: Fix XML-RPC client to retry when the server shuts down a
  persistent connection.  This was a regression related to the new
  http.client.RemoteDisconnected exception in 3.5.0a4.

* bpo-25913: Leading "<~" is optional now in base64.a85decode() with
  adobe=True.  Patch by Swati Jaiswal.

* bpo-26186: Remove an invalid type check in
  importlib.util.LazyLoader.

* bpo-26367: importlib.__import__() raises SystemError like
  builtins.__import__() when "level" is specified but without an
  accompanying package specified.

* bpo-26309: In the “socketserver” module, shut down the request
  (closing the connected socket) when verify_request() returns false.
  Patch by Aviv Palivoda.

* bpo-25995: os.walk() no longer uses FDs proportional to the tree
  depth.

* bpo-26117: The os.scandir() iterator now closes file descriptor not
  only when the iteration is finished, but when it was failed with
  error.

* bpo-25911: Restored support of bytes paths in os.walk() on Windows.

* bpo-26045: Add UTF-8 suggestion to error message when posting a non-
  Latin-1 string with http.client.

* bpo-12923: Reset FancyURLopener’s redirect counter even if there is
  an exception. Based on patches by Brian Brazil and Daniel Rocco.

* bpo-25945: Fixed a crash when unpickle the functools.partial object
  with wrong state. Fixed a leak in failed functools.partial
  constructor. “args” and “keywords” attributes of functools.partial
  have now always types tuple and dict correspondingly.

* bpo-26202: copy.deepcopy() now correctly copies range() objects with
  non-atomic attributes.

* bpo-23076: Path.glob() now raises a ValueError if it’s called with
  an invalid pattern. Patch by Thomas Nyberg.

* bpo-19883: Fixed possible integer overflows in zipimport.

* bpo-26227: On Windows, getnameinfo(), gethostbyaddr() and
  gethostbyname_ex() functions of the socket module now decode the
  hostname from the ANSI code page rather than UTF-8.

* bpo-26147: xmlrpc now works with strings not encodable with used
  non-UTF-8 encoding.

* bpo-25935: Garbage collector now breaks reference loops with
  OrderedDict.

* bpo-16620: Fixed AttributeError in msilib.Directory.glob().

* bpo-26013: Added compatibility with broken protocol 2 pickles
  created in old Python 3 versions (3.4.3 and lower).

* bpo-25850: Use cross-compilation by default for 64-bit Windows.

* bpo-17633: Improve zipimport’s support for namespace packages.

* bpo-24705: Fix sysconfig._parse_makefile not expanding ${} vars
  appearing before $() vars.

* bpo-22138: Fix mock.patch behavior when patching descriptors.
  Restore original values after patching. Patch contributed by Sean
  McCully.

* bpo-25672: In the ssl module, enable the SSL_MODE_RELEASE_BUFFERS
  mode option if it is safe to do so.

* bpo-26012: Don’t traverse into symlinks for "**" pattern in
  pathlib.Path.[r]glob().

* bpo-24120: Ignore PermissionError when traversing a tree with
  pathlib.Path.[r]glob(). Patch by Ulrich Petri.

* bpo-25447: fileinput now uses sys.stdin as-is if it does not have a
  buffer attribute (restores backward compatibility).

* bpo-25447: Copying the lru_cache() wrapper object now always works,
  independently from the type of the wrapped object (by returning the
  original object unchanged).

* bpo-24103: Fixed possible use after free in
  ElementTree.XMLPullParser.

* bpo-25860: os.fwalk() no longer skips remaining directories when
  error occurs. Original patch by Samson Lee.

* bpo-25914: Fixed and simplified OrderedDict.__sizeof__.

* bpo-25902: Fixed various refcount issues in ElementTree iteration.

* bpo-25717: Restore the previous behaviour of tolerating most fstat()
  errors when opening files.  This was a regression in 3.5a1, and
  stopped anonymous temporary files from working in special cases.

* bpo-24903: Fix regression in number of arguments compileall accepts
  when ‘-d’ is specified.  The check on the number of arguments has
  been dropped completely as it never worked correctly anyway.

* bpo-25764: In the subprocess module, preserve any exception caused
  by fork() failure when preexec_fn is used.

* bpo-6478: _strptime’s regexp cache now is reset after changing
  timezone with time.tzset().

* bpo-14285: When executing a package with the “python -m package”
  option, and package initialization fails, a proper traceback is now
  reported.  The “runpy” module now lets exceptions from package
  initialization pass back to the caller, rather than raising
  ImportError.

* bpo-19771: Also in runpy and the “-m” option, omit the irrelevant
  message “… is a package and cannot be directly executed” if the
  package could not even be initialized (e.g. due to a bad "*.pyc"
  file).

* bpo-25177: Fixed problem with the mean of very small and very large
  numbers. As a side effect, statistics.mean and statistics.variance
  should be significantly faster.

* bpo-25718: Fixed copying object with state with boolean value is
  false.

* bpo-10131: Fixed deep copying of minidom documents.  Based on patch
  by Marian Ganisin.

* bpo-25725: Fixed a reference leak in pickle.loads() when unpickling
  invalid data including tuple instructions.

* bpo-25663: In the Readline completer, avoid listing duplicate global
  names, and search the global namespace before searching builtins.

* bpo-25688: Fixed file leak in ElementTree.iterparse() raising an
  error.

* bpo-23914: Fixed SystemError raised by unpickler on broken pickle
  data.

* bpo-25691: Fixed crash on deleting ElementTree.Element attributes.

* bpo-25624: ZipFile now always writes a ZIP_STORED header for
  directory entries.  Patch by Dingyuan Wang.

* Skip getaddrinfo if host is already resolved. Patch by A. Jesse
  Jiryu Davis.

* bpo-26050: Add asyncio.StreamReader.readuntil() method. Patch by
  Марк Коренберг.

* bpo-25924: Avoid unnecessary serialization of getaddrinfo(3) calls
  on OS X versions 10.5 or higher.  Original patch by A. Jesse Jiryu
  Davis.

* bpo-26406: Avoid unnecessary serialization of getaddrinfo(3) calls
  on current versions of OpenBSD and NetBSD.  Patch by A. Jesse Jiryu
  Davis.

* bpo-26848: Fix asyncio/subprocess.communicate() to handle empty
  input. Patch by Jack O’Connor.

* bpo-27040: Add loop.get_exception_handler method

* bpo-27041: asyncio: Add loop.create_future method

* bpo-27223: asyncio: Fix _read_ready and _write_ready to respect
  _conn_lost. Patch by Łukasz Langa.

* bpo-22970: asyncio: Fix inconsistency cancelling Condition.wait.
  Patch by David Coles.


IDLE
----

* bpo-5124: Paste with text selected now replaces the selection on
  X11. This matches how paste works on Windows, Mac, most modern Linux
  apps, and ttk widgets. Original patch by Serhiy Storchaka.

* bpo-24759: Make clear in idlelib.idle_test.__init__ that the
  directory is a private implementation of test.test_idle and tool for
  maintainers.

* bpo-27196: Stop ‘ThemeChanged’ warnings when running IDLE tests.
  These persisted after other warnings were suppressed in #20567.
  Apply Serhiy Storchaka’s update_idletasks solution to four test
  files. Record this additional advice in idle_test/README.txt

* bpo-20567: Revise idle_test/README.txt with advice about avoiding tk
  warning messages from tests.  Apply advice to several IDLE tests.

* bpo-27117: Make colorizer htest and turtledemo work with dark
  themes. Move code for configuring text widget colors to a new
  function.

* bpo-26673: When tk reports font size as 0, change to size 10. Such
  fonts on Linux prevented the configuration dialog from opening.

* bpo-21939: Add test for IDLE’s percolator. Original patch by
  Saimadhav Heblikar.

* bpo-21676: Add test for IDLE’s replace dialog. Original patch by
  Saimadhav Heblikar.

* bpo-18410: Add test for IDLE’s search dialog. Original patch by
  Westley Martínez.

* bpo-21703: Add test for IDLE’s undo delegator. Original patch by
  Saimadhav Heblikar .

* bpo-27044: Add ConfigDialog.remove_var_callbacks to stop memory
  leaks.

* bpo-23977: Add more asserts to test_delegator.

* bpo-20640: Add tests for idlelib.configHelpSourceEdit. Patch by
  Saimadhav Heblikar.

* In the ‘IDLE-console differences’ section of the IDLE doc, clarify
  how running with IDLE affects sys.modules and the standard streams.

* bpo-25507: fix incorrect change in IOBinding that prevented
  printing. Augment IOBinding htest to include all major IOBinding
  functions.

* bpo-25905: Revert unwanted conversion of ‘ to ’ RIGHT SINGLE
  QUOTATION MARK in README.txt and open this and NEWS.txt with
  ‘ascii’. Re-encode CREDITS.txt to utf-8 and open it with ‘utf-8’.


Documentation
-------------

* bpo-19489: Moved the search box from the sidebar to the header and
  footer of each page. Patch by Ammar Askar.

* bpo-24136: Document the new **PEP 448** unpacking syntax of 3.5.

* bpo-26736: Used HTTPS for external links in the documentation if
  possible.

* bpo-6953: Rework the Readline module documentation to group related
  functions together, and add more details such as what underlying
  Readline functions and variables are accessed.

* bpo-23606: Adds note to ctypes documentation regarding cdll.msvcrt.

* bpo-25500: Fix documentation to not claim that __import__ is
  searched for in the global scope.

* bpo-26014: Update 3.x packaging documentation: * “See also” links to
  the new docs are now provided in the legacy pages * links to
  setuptools documentation have been updated


Tests
-----

* bpo-21916: Added tests for the turtle module.  Patch by ingrid,
  Gregory Loyse and Jelle Zijlstra.

* bpo-26523: The multiprocessing thread pool
  (multiprocessing.dummy.Pool) was untested.

* bpo-26015: Added new tests for pickling iterators of mutable
  sequences.

* bpo-26325: Added test.support.check_no_resource_warning() to check
  that no ResourceWarning is emitted.

* bpo-25940: Changed test_ssl to use self-signed.pythontest.net.  This
  avoids relying on svn.python.org, which recently changed root
  certificate.

* bpo-25616: Tests for OrderedDict are extracted from test_collections
  into separate file test_ordered_dict.

* bpo-26583: Skip test_timestamp_overflow in test_import if bytecode
  files cannot be written.


Build
-----

* bpo-26884: Fix linking extension modules for cross builds. Patch by
  Xavier de Gaye.

* bpo-22359: Disable the rules for running _freeze_importlib and pgen
  when cross-compiling.  The output of these programs is normally
  saved with the source code anyway, and is still regenerated when
  doing a native build. Patch by Xavier de Gaye.

* bpo-27229: Fix the cross-compiling pgen rule for in-tree builds.
  Patch by Xavier de Gaye.

* bpo-21668: Link audioop, _datetime, _ctypes_test modules to libm,
  except on Mac OS X. Patch written by Xavier de Gaye.

* bpo-25702: A –with-lto configure option has been added that will
  enable link time optimizations at build time during a make profile-
  opt. Some compilers and toolchains are known to not produce stable
  code when using LTO, be sure to test things thoroughly before
  relying on it. It can provide a few % speed up over profile-opt
  alone.

* bpo-26624: Adds validation of ucrtbase[d].dll version with warning
  for old versions.

* bpo-17603: Avoid error about nonexistent fileblocks.o file by using
  a lower-level check for st_blocks in struct stat.

* bpo-26079: Fixing the build output folder for tix-8.4.3.6. Patch by
  Bjoern Thiel.

* bpo-26465: Update Windows builds to use OpenSSL 1.0.2g.

* bpo-24421: Compile Modules/_math.c once, before building extensions.
  Previously it could fail to compile properly if the math and cmath
  builds were concurrent.

* bpo-25348: Added "--pgo" and "--pgo-job" arguments to
  "PCbuild\build.bat" for building with Profile-Guided Optimization.
  The old "PCbuild\build_pgo.bat" script is now deprecated, and simply
  calls "PCbuild\build.bat --pgo %*".

* bpo-25827: Add support for building with ICC to "configure",
  including a new "--with-icc" flag.

* bpo-25696: Fix installation of Python on UNIX with make -j9.

* bpo-26930: Update OS X 10.5+ 32-bit-only installer to build and link
  with OpenSSL 1.0.2h.

* bpo-26268: Update Windows builds to use OpenSSL 1.0.2f.

* bpo-25136: Support Apple Xcode 7’s new textual SDK stub libraries.

* bpo-24324: Do not enable unreachable code warnings when using gcc as
  the option does not work correctly in older versions of gcc and has
  been silently removed as of gcc-4.5.


Windows
-------

* bpo-27053: Updates make_zip.py to correctly generate library ZIP
  file.

* bpo-26268: Update the prepare_ssl.py script to handle OpenSSL
  releases that don’t include the contents of the include directory
  (that is, 1.0.2e and later).

* bpo-26071: bdist_wininst created binaries fail to start and find
  32bit Python

* bpo-26073: Update the list of magic numbers in launcher

* bpo-26065: Excludes venv from library when generating embeddable
  distro.

* bpo-17500: Remove unused and outdated icons. (See also:
  https://github.com/python/pythondotorg/issues/945)


Tools/Demos
-----------

* bpo-26799: Fix python-gdb.py: don’t get C types once when the Python
  code is loaded, but get C types on demand. The C types can change if
  python-gdb.py is loaded before the Python executable. Patch written
  by Thomas Ilsche.

* bpo-26271: Fix the Freeze tool to properly use flags passed through
  configure. Patch by Daniel Shaulov.

* bpo-26489: Add dictionary unpacking support to
  Tools/parser/unparse.py. Patch by Guo Ci Teo.

* bpo-26316: Fix variable name typo in Argument Clinic.


Python 3.5.1 final
==================

*Release date: 2015-12-06*


Core and Builtins
-----------------

* bpo-25709: Fixed problem with in-place string concatenation and
  utf-8 cache.


Windows
-------

* bpo-25715: Python 3.5.1 installer shows wrong upgrade path and
  incorrect logic for launcher detection.


Python 3.5.1 release candidate 1
================================

*Release date: 2015-11-22*


Core and Builtins
-----------------

* bpo-25630: Fix a possible segfault during argument parsing in
  functions that accept filesystem paths.

* bpo-23564: Fixed a partially broken sanity check in the
  _posixsubprocess internals regarding how fds_to_pass were passed to
  the child.  The bug had no actual impact as subprocess.py already
  avoided it.

* bpo-25388: Fixed tokenizer crash when processing undecodable source
  code with a null byte.

* bpo-25462: The hash of the key now is calculated only once in most
  operations in C implementation of OrderedDict.

* bpo-22995: Default implementation of __reduce__ and __reduce_ex__
  now rejects builtin types with not defined __new__.

* bpo-25555: Fix parser and AST: fill lineno and col_offset of “arg”
  node when compiling AST from Python objects.

* bpo-24802: Avoid buffer overreads when int(), float(), compile(),
  exec() and eval() are passed bytes-like objects.  These objects are
  not necessarily terminated by a null byte, but the functions assumed
  they were.

* bpo-24726: Fixed a crash and leaking NULL in repr() of OrderedDict
  that was mutated by direct calls of dict methods.

* bpo-25449: Iterating OrderedDict with keys with unstable hash now
  raises KeyError in C implementations as well as in Python
  implementation.

* bpo-25395: Fixed crash when highly nested OrderedDict structures
  were garbage collected.

* bpo-25274: sys.setrecursionlimit() now raises a RecursionError if
  the new recursion limit is too low depending at the current
  recursion depth. Modify also the “lower-water mark” formula to make
  it monotonic. This mark is used to decide when the overflowed flag
  of the thread state is reset.

* bpo-24402: Fix input() to prompt to the redirected stdout when
  sys.stdout.fileno() fails.

* bpo-24806: Prevent builtin types that are not allowed to be
  subclassed from being subclassed through multiple inheritance.

* bpo-24848: Fixed a number of bugs in UTF-7 decoding of misformed
  data.

* bpo-25280: Import trace messages emitted in verbose (-v) mode are no
  longer formatted twice.

* bpo-25003: On Solaris 11.3 or newer, os.urandom() now uses the
  getrandom() function instead of the getentropy() function. The
  getentropy() function is blocking to generate very good quality
  entropy, os.urandom() doesn’t need such high-quality entropy.

* bpo-25182: The stdprinter (used as sys.stderr before the io module
  is imported at startup) now uses the backslashreplace error handler.

* bpo-25131: Make the line number and column offset of set/dict
  literals and comprehensions correspond to the opening brace.

* bpo-25150: Hide the private _Py_atomic_xxx symbols from the public
  Python.h header to fix a compilation error with OpenMP.
  PyThreadState_GET() becomes an alias to PyThreadState_Get() to avoid
  ABI incompatibilities.


Library
-------

* bpo-25626: Change three zlib functions to accept sizes that fit in
  Py_ssize_t, but internally cap those sizes to UINT_MAX.  This
  resolves a regression in 3.5 where GzipFile.read() failed to read
  chunks larger than 2 or 4 GiB.  The change affects the
  zlib.Decompress.decompress() max_length parameter, the
  zlib.decompress() bufsize parameter, and the zlib.Decompress.flush()
  length parameter.

* bpo-25583: Avoid incorrect errors raised by
  os.makedirs(exist_ok=True) when the OS gives priority to errors such
  as EACCES over EEXIST.

* bpo-25593: Change semantics of EventLoop.stop() in asyncio.

* bpo-6973: When we know a subprocess.Popen process has died, do not
  allow the send_signal(), terminate(), or kill() methods to do
  anything as they could potentially signal a different process.

* bpo-25590: In the Readline completer, only call getattr() once per
  attribute.

* bpo-25498: Fix a crash when garbage-collecting ctypes objects
  created by wrapping a memoryview.  This was a regression made in
  3.5a1.  Based on patch by Eryksun.

* bpo-25584: Added “escape” to the __all__ list in the glob module.

* bpo-25584: Fixed recursive glob() with patterns starting with "**".

* bpo-25446: Fix regression in smtplib’s AUTH LOGIN support.

* bpo-18010: Fix the pydoc web server’s module search function to
  handle exceptions from importing packages.

* bpo-25554: Got rid of circular references in regular expression
  parsing.

* bpo-25510: fileinput.FileInput.readline() now returns b’’ instead of
  ‘’ at the end if the FileInput was opened with binary mode. Patch by
  Ryosuke Ito.

* bpo-25503: Fixed inspect.getdoc() for inherited docstrings of
  properties. Original patch by John Mark Vandenberg.

* bpo-25515: Always use os.urandom as a source of randomness in
  uuid.uuid4.

* bpo-21827: Fixed textwrap.dedent() for the case when largest common
  whitespace is a substring of smallest leading whitespace. Based on
  patch by Robert Li.

* bpo-25447: The lru_cache() wrapper objects now can be copied and
  pickled (by returning the original object unchanged).

* bpo-25390: typing: Don’t crash on Union[str, Pattern].

* bpo-25441: asyncio: Raise error from drain() when socket is closed.

* bpo-25410: Cleaned up and fixed minor bugs in C implementation of
  OrderedDict.

* bpo-25411: Improved Unicode support in SMTPHandler through better
  use of the email package. Thanks to user simon04 for the patch.

* bpo-25407: Remove mentions of the formatter module being removed in
  Python 3.6.

* bpo-25406: Fixed a bug in C implementation of
  OrderedDict.move_to_end() that caused segmentation fault or hang in
  iterating after moving several items to the start of ordered dict.

* bpo-25364: zipfile now works in threads disabled builds.

* bpo-25328: smtpd’s SMTPChannel now correctly raises a ValueError if
  both decode_data and enable_SMTPUTF8 are set to true.

* bpo-25316: distutils raises OSError instead of
  DistutilsPlatformError when MSVC is not installed.

* bpo-25380: Fixed protocol for the STACK_GLOBAL opcode in
  pickletools.opcodes.

* bpo-23972: Updates asyncio datagram create method allowing reuseport
  and reuseaddr socket options to be set prior to binding the socket.
  Mirroring the existing asyncio create_server method the reuseaddr
  option for datagram sockets defaults to True if the O/S is ‘posix’
  (except if the platform is Cygwin). Patch by Chris Laws.

* bpo-25304: Add asyncio.run_coroutine_threadsafe().  This lets you
  submit a coroutine to a loop from another thread, returning a
  concurrent.futures.Future.  By Vincent Michel.

* bpo-25232: Fix CGIRequestHandler to split the query from the URL at
  the first question mark (?) rather than the last. Patch from Xiang
  Zhang.

* bpo-24657: Prevent CGIRequestHandler from collapsing slashes in the
  query part of the URL as if it were a path. Patch from Xiang Zhang.

* bpo-24483: C implementation of functools.lru_cache() now calculates
  key’s hash only once.

* bpo-22958: Constructor and update method of
  weakref.WeakValueDictionary now accept the self and the dict keyword
  arguments.

* bpo-22609: Constructor of collections.UserDict now accepts the self
  keyword argument.

* bpo-25111: Fixed comparison of traceback.FrameSummary.

* bpo-25262: Added support for BINBYTES8 opcode in Python
  implementation of unpickler. Highest 32 bits of 64-bit size for
  BINUNICODE8 and BINBYTES8 opcodes no longer silently ignored on
  32-bit platforms in C implementation.

* bpo-25034: Fix string.Formatter problem with auto-numbering and
  nested format_specs. Patch by Anthon van der Neut.

* bpo-25233: Rewrite the guts of asyncio.Queue and asyncio.Semaphore
  to be more understandable and correct.

* bpo-25203: Failed readline.set_completer_delims() no longer left the
  module in inconsistent state.

* bpo-23600: Default implementation of tzinfo.fromutc() was returning
  wrong results in some cases.

* bpo-23329: Allow the ssl module to be built with older versions of
  LibreSSL.

* Prevent overflow in _Unpickler_Read.

* bpo-25047: The XML encoding declaration written by Element Tree now
  respects the letter case given by the user. This restores the
  ability to write encoding names in uppercase like “UTF-8”, which
  worked in Python 2.

* bpo-25135: Make deque_clear() safer by emptying the deque before
  clearing. This helps avoid possible reentrancy issues.

* bpo-19143: platform module now reads Windows version from
  kernel32.dll to avoid compatibility shims.

* bpo-25092: Fix datetime.strftime() failure when errno was already
  set to EINVAL.

* bpo-23517: Fix rounding in fromtimestamp() and utcfromtimestamp()
  methods of datetime.datetime: microseconds are now rounded to
  nearest with ties going to nearest even integer (ROUND_HALF_EVEN),
  instead of being rounding towards minus infinity (ROUND_FLOOR). It’s
  important that these methods use the same rounding mode than
  datetime.timedelta to keep the property: (datetime(1970,1,1) +
  timedelta(seconds=t)) == datetime.utcfromtimestamp(t). It also the
  rounding mode used by round(float) for example.

* bpo-25155: Fix datetime.datetime.now() and
  datetime.datetime.utcnow() on Windows to support date after year
  2038. It was a regression introduced in Python 3.5.0.

* bpo-25108: Omitted internal frames in traceback functions
  print_stack(), format_stack(), and extract_stack() called without
  arguments.

* bpo-25118: Fix a regression of Python 3.5.0 in os.waitpid() on
  Windows.

* bpo-24684: socket.socket.getaddrinfo() now calls
  PyUnicode_AsEncodedString() instead of calling the encode() method
  of the host, to handle correctly custom string with an encode()
  method which doesn’t return a byte string. The encoder of the IDNA
  codec is now called directly instead of calling the encode() method
  of the string.

* bpo-25060: Correctly compute stack usage of the BUILD_MAP opcode.

* bpo-24857: Comparing call_args to a long sequence now correctly
  returns a boolean result instead of raising an exception.  Patch by
  A Kaptur.

* bpo-23144: Make sure that HTMLParser.feed() returns all the data,
  even when convert_charrefs is True.

* bpo-24982: shutil.make_archive() with the “zip” format now adds
  entries for directories (including empty directories) in ZIP file.

* bpo-25019: Fixed a crash caused by setting non-string key of expat
  parser. Based on patch by John Leitch.

* bpo-16180: Exit pdb if file has syntax error, instead of trapping
  user in an infinite loop.  Patch by Xavier de Gaye.

* bpo-24891: Fix a race condition at Python startup if the file
  descriptor of stdin (0), stdout (1) or stderr (2) is closed while
  Python is creating sys.stdin, sys.stdout and sys.stderr objects.
  These attributes are now set to None if the creation of the object
  failed, instead of raising an OSError exception. Initial patch
  written by Marco Paolini.

* bpo-24992: Fix error handling and a race condition (related to
  garbage collection) in collections.OrderedDict constructor.

* bpo-24881: Fixed setting binary mode in Python implementation of
  FileIO on Windows and Cygwin.  Patch from Akira Li.

* bpo-25578: Fix (another) memory leak in SSLSocket.getpeercer().

* bpo-25530: Disable the vulnerable SSLv3 protocol by default when
  creating ssl.SSLContext.

* bpo-25569: Fix memory leak in SSLSocket.getpeercert().

* bpo-25471: Sockets returned from accept() shouldn’t appear to be
  nonblocking.

* bpo-25319: When threading.Event is reinitialized, the underlying
  condition should use a regular lock rather than a recursive lock.

* bpo-21112: Fix regression in unittest.expectedFailure on subclasses.
  Patch from Berker Peksag.

* bpo-24764: cgi.FieldStorage.read_multi() now ignores the Content-
  Length header in part headers. Patch written by Peter Landry and
  reviewed by Pierre Quentel.

* bpo-24913: Fix overrun error in deque.index(). Found by John Leitch
  and Bryce Darling.

* bpo-24774: Fix docstring in http.server.test. Patch from Chiu-Hsiang
  Hsu.

* bpo-21159: Improve message in
  configparser.InterpolationMissingOptionError. Patch from Łukasz
  Langa.

* bpo-20362: Honour TestCase.longMessage correctly in assertRegex.
  Patch from Ilia Kurenkov.

* bpo-23572: Fixed functools.singledispatch on classes with falsy
  metaclasses.  Patch by Ethan Furman.

* asyncio: ensure_future() now accepts awaitable objects.


IDLE
----

* bpo-15348: Stop the debugger engine (normally in a user process)
  before closing the debugger window (running in the IDLE process).
  This prevents the RuntimeErrors that were being caught and ignored.

* bpo-24455: Prevent IDLE from hanging when a) closing the shell while
  the debugger is active (15347); b) closing the debugger with the [X]
  button (15348); and c) activating the debugger when already active
  (24455). The patch by Mark Roseman does this by making two changes.
  1. Suspend and resume the gui.interaction method with the tcl vwait
  mechanism intended for this purpose (instead of root.mainloop &
  .quit). 2. In gui.run, allow any existing interaction to terminate
  first.

* Change ‘The program’ to ‘Your program’ in an IDLE ‘kill program?’
  message to make it clearer that the program referred to is the
  currently running user program, not IDLE itself.

* bpo-24750: Improve the appearance of the IDLE editor window status
  bar. Patch by Mark Roseman.

* bpo-25313: Change the handling of new built-in text color themes to
  better address the compatibility problem introduced by the addition
  of IDLE Dark. Consistently use the revised idleConf.CurrentTheme
  everywhere in idlelib.

* bpo-24782: Extension configuration is now a tab in the IDLE
  Preferences dialog rather than a separate dialog.  The former tabs
  are now a sorted list.  Patch by Mark Roseman.

* bpo-22726: Re-activate the config dialog help button with some
  content about the other buttons and the new IDLE Dark theme.

* bpo-24820: IDLE now has an ‘IDLE Dark’ built-in text color theme. It
  is more or less IDLE Classic inverted, with a cobalt blue
  background. Strings, comments, keywords, … are still green, red,
  orange, … . To use it with IDLEs released before November 2015, hit
  the ‘Save as New Custom Theme’ button and enter a new name, such as
  ‘Custom Dark’.  The custom theme will work with any IDLE release,
  and can be modified.

* bpo-25224: README.txt is now an idlelib index for IDLE developers
  and curious users. The previous user content is now in the IDLE doc
  chapter. ‘IDLE’ now means ‘Integrated Development and Learning
  Environment’.

* bpo-24820: Users can now set breakpoint colors in Settings -> Custom
  Highlighting. Original patch by Mark Roseman.

* bpo-24972: Inactive selection background now matches active
  selection background, as configured by users, on all systems.  Found
  items are now always highlighted on Windows.  Initial patch by Mark
  Roseman.

* bpo-24570: Idle: make calltip and completion boxes appear on Macs
  affected by a tk regression.  Initial patch by Mark Roseman.

* bpo-24988: Idle ScrolledList context menus (used in debugger) now
  work on Mac Aqua. Patch by Mark Roseman.

* bpo-24801: Make right-click for context menu work on Mac Aqua. Patch
  by Mark Roseman.

* bpo-25173: Associate tkinter messageboxes with a specific widget.
  For Mac OSX, make them a ‘sheet’.  Patch by Mark Roseman.

* bpo-25198: Enhance the initial html viewer now used for Idle Help.
  Properly indent fixed-pitch text (patch by Mark Roseman). Give code
  snippet a very Sphinx-like light blueish-gray background. Re-use
  initial width and height set by users for shell and editor. When the
  Table of Contents (TOC) menu is used, put the section header at the
  top of the screen.

* bpo-25225: Condense and rewrite Idle doc section on text colors.

* bpo-21995: Explain some differences between IDLE and console Python.

* bpo-22820: Explain need for *print* when running file from Idle
  editor.

* bpo-25224: Doc: augment Idle feature list and no-subprocess section.

* bpo-25219: Update doc for Idle command line options. Some were
  missing and notes were not correct.

* bpo-24861: Most of idlelib is private and subject to change. Use
  idleib.idle.* to start Idle. See idlelib.__init__.__doc__.

* bpo-25199: Idle: add synchronization comments for future
  maintainers.

* bpo-16893: Replace help.txt with help.html for Idle doc display. The
  new idlelib/help.html is rstripped Doc/build/html/library/idle.html.
  It looks better than help.txt and will better document Idle as
  released. The tkinter html viewer that works for this file was
  written by Mark Roseman. The now unused EditorWindow.HelpDialog
  class and helt.txt file are deprecated.

* bpo-24199: Deprecate unused idlelib.idlever with possible removal in
  3.6.

* bpo-24790: Remove extraneous code (which also create 2 & 3
  conflicts).


Documentation
-------------

* bpo-22558: Add remaining doc links to source code for Python-coded
  modules. Patch by Yoni Lavi.

* bpo-12067: Rewrite Comparisons section in the Expressions chapter of
  the language reference. Some of the details of comparing mixed types
  were incorrect or ambiguous. NotImplemented is only relevant at a
  lower level than the Expressions chapter. Added details of comparing
  range() objects, and default behaviour and consistency suggestions
  for user-defined classes. Patch from Andy Maier.

* bpo-24952: Clarify the default size argument of stack_size() in the
  “threading” and “_thread” modules. Patch from Mattip.

* bpo-23725: Overhaul tempfile docs. Note deprecated status of mktemp.
  Patch from Zbigniew Jędrzejewski-Szmek.

* bpo-24808: Update the types of some PyTypeObject fields.  Patch by
  Joseph Weston.

* bpo-22812: Fix unittest discovery examples. Patch from Pam
  McA’Nulty.


Tests
-----

* bpo-25449: Added tests for OrderedDict subclasses.

* bpo-25099: Make test_compileall not fail when an entry on sys.path
  cannot be written to (commonly seen in administrative installs on
  Windows).

* bpo-23919: Prevents assert dialogs appearing in the test suite.

* "PCbuild\rt.bat" now accepts an unlimited number of arguments to
  pass along to regrtest.py.  Previously there was a limit of 9.


Build
-----

* bpo-24915: Add LLVM support for PGO builds and use the test suite to
  generate the profile data. Initial patch by Alecsandru Patrascu of
  Intel.

* bpo-24910: Windows MSIs now have unique display names.

* bpo-24986: It is now possible to build Python on Windows without
  errors when external libraries are not available.


Windows
-------

* bpo-25450: Updates shortcuts to start Python in installation
  directory.

* bpo-25164: Changes default all-users install directory to match per-
  user directory.

* bpo-25143: Improves installer error messages for unsupported
  platforms.

* bpo-25163: Display correct directory in installer when using non-
  default settings.

* bpo-25361: Disables use of SSE2 instructions in Windows 32-bit build

* bpo-25089: Adds logging to installer for case where launcher is not
  selected on upgrade.

* bpo-25165: Windows uninstallation should not remove launcher if
  other versions remain

* bpo-25112: py.exe launcher is missing icons

* bpo-25102: Windows installer does not precompile for -O or -OO.

* bpo-25081: Makes Back button in installer go back to upgrade page
  when upgrading.

* bpo-25091: Increases font size of the installer.

* bpo-25126: Clarifies that the non-web installer will download some
  components.

* bpo-25213: Restores requestedExecutionLevel to manifest to disable
  UAC virtualization.

* bpo-25022: Removed very outdated PC/example_nt/ directory.


Tools/Demos
-----------

* bpo-25440: Fix output of python-config –extension-suffix.


Python 3.5.0 final
==================

*Release date: 2015-09-13*


Build
-----

* bpo-25071: Windows installer should not require TargetDir parameter
  when installing quietly.


Python 3.5.0 release candidate 4
================================

*Release date: 2015-09-09*


Library
-------

* bpo-25029: Fixes MemoryError in test_strptime.


Build
-----

* bpo-25027: Reverts partial-static build options and adds
  vcruntime140.dll to Windows installation.


Python 3.5.0 release candidate 3
================================

*Release date: 2015-09-07*


Core and Builtins
-----------------

* bpo-24305: Prevent import subsystem stack frames from being counted
  by the warnings.warn(stacklevel=) parameter.

* bpo-24912: Prevent __class__ assignment to immutable built-in
  objects.

* bpo-24975: Fix AST compilation for **PEP 448** syntax.


Library
-------

* bpo-24917: time_strftime() buffer over-read.

* bpo-24748: To resolve a compatibility problem found with py2exe and
  pywin32, imp.load_dynamic() once again ignores previously loaded
  modules to support Python modules replacing themselves with
  extension modules. Patch by Petr Viktorin.

* bpo-24635: Fixed a bug in typing.py where isinstance([],
  typing.Iterable) would return True once, then False on subsequent
  calls.

* bpo-24989: Fixed buffer overread in BytesIO.readline() if a position
  is set beyond size.  Based on patch by John Leitch.

* bpo-24913: Fix overrun error in deque.index(). Found by John Leitch
  and Bryce Darling.


Python 3.5.0 release candidate 2
================================

*Release date: 2015-08-25*


Core and Builtins
-----------------

* bpo-24769: Interpreter now starts properly when dynamic loading is
  disabled.  Patch by Petr Viktorin.

* bpo-21167: NAN operations are now handled correctly when python is
  compiled with ICC even if -fp-model strict is not specified.

* bpo-24492: A “package” lacking a __name__ attribute when trying to
  perform a "from .. import ..." statement will trigger an ImportError
  instead of an AttributeError.


Library
-------

* bpo-24847: Removes vcruntime140.dll dependency from Tcl/Tk.

* bpo-24839: platform._syscmd_ver raises DeprecationWarning

* bpo-24867: Fix Task.get_stack() for ‘async def’ coroutines


Python 3.5.0 release candidate 1
================================

*Release date: 2015-08-09*


Core and Builtins
-----------------

* bpo-24667: Resize odict in all cases that the underlying dict
  resizes.


Library
-------

* bpo-24824: Signatures of codecs.encode() and codecs.decode() now are
  compatible with pydoc.

* bpo-24634: Importing uuid should not try to load libc on Windows

* bpo-24798: _msvccompiler.py doesn’t properly support manifests

* bpo-4395: Better testing and documentation of binary operators.
  Patch by Martin Panter.

* bpo-23973: Update typing.py from GitHub repo.

* bpo-23004: mock_open() now reads binary data correctly when the type
  of read_data is bytes.  Initial patch by Aaron Hill.

* bpo-23888: Handle fractional time in cookie expiry. Patch by ssh.

* bpo-23652: Make it possible to compile the select module against the
  libc headers from the Linux Standard Base, which do not include some
  EPOLL macros.  Patch by Matt Frank.

* bpo-22932: Fix timezones in email.utils.formatdate. Patch from
  Dmitry Shachnev.

* bpo-23779: imaplib raises TypeError if authenticator tries to abort.
  Patch from Craig Holmquist.

* bpo-23319: Fix ctypes.BigEndianStructure, swap correctly bytes.
  Patch written by Matthieu Gautier.

* bpo-23254: Document how to close the TCPServer listening socket.
  Patch from Martin Panter.

* bpo-19450: Update Windows and OS X installer builds to use SQLite
  3.8.11.

* bpo-17527: Add PATCH to wsgiref.validator. Patch from Luca
  Sbardella.

* bpo-24791: Fix grammar regression for call syntax: ‘g(*a or b)’.


IDLE
----

* bpo-23672: Allow Idle to edit and run files with astral chars in
  name. Patch by Mohd Sanad Zaki Rizvi.

* bpo-24745: Idle editor default font. Switch from Courier to
  platform-sensitive TkFixedFont.  This should not affect current
  customized font selections.  If there is a problem, edit
  $HOME/.idlerc/config-main.cfg and remove ‘fontxxx’ entries from
  [Editor Window].  Patch by Mark Roseman.

* bpo-21192: Idle editor. When a file is run, put its name in the
  restart bar. Do not print false prompts. Original patch by Adnan
  Umer.

* bpo-13884: Idle menus. Remove tearoff lines. Patch by Roger Serwy.


Documentation
-------------

* bpo-24129: Clarify the reference documentation for name resolution.
  This includes removing the assumption that readers will be familiar
  with the name resolution scheme Python used prior to the
  introduction of lexical scoping for function namespaces. Patch by
  Ivan Levkivskyi.

* bpo-20769: Improve reload() docs. Patch by Dorian Pula.

* bpo-23589: Remove duplicate sentence from the FAQ.  Patch by Yongzhi
  Pan.

* bpo-24729: Correct IO tutorial to match implementation regarding
  encoding parameter to open function.


Tests
-----

* bpo-24751: When running regrtest with the "-w" command line option,
  a test run is no longer marked as a failure if all tests succeed
  when re-run.


Python 3.5.0 beta 4
===================

*Release date: 2015-07-26*


Core and Builtins
-----------------

* bpo-23573: Restored optimization of bytes.rfind() and
  bytearray.rfind() for single-byte argument on Linux.

* bpo-24569: Make **PEP 448** dictionary evaluation more consistent.

* bpo-24583: Fix crash when set is mutated while being updated.

* bpo-24407: Fix crash when dict is mutated while being updated.

* bpo-24619: New approach for tokenizing async/await. As a
  consequence, it is now possible to have one-line ‘async def foo():
  await ..’ functions.

* bpo-24687: Plug refleak on SyntaxError in function parameters
  annotations.

* bpo-15944: memoryview: Allow arbitrary formats when casting to
  bytes. Patch by Martin Panter.


Library
-------

* bpo-23441: rcompleter now prints a tab character instead of
  displaying possible completions for an empty word.  Initial patch by
  Martin Sekera.

* bpo-24683: Fixed crashes in _json functions called with arguments of
  inappropriate type.

* bpo-21697: shutil.copytree() now correctly handles symbolic links
  that point to directories.  Patch by Eduardo Seabra and Thomas
  Kluyver.

* bpo-14373: Fixed segmentation fault when gc.collect() is called
  during constructing lru_cache (C implementation).

* bpo-24695: Fix a regression in traceback.print_exception().  If
  exc_traceback is None we shouldn’t print a traceback header like
  described in the documentation.

* bpo-24620: Random.setstate() now validates the value of state last
  element.

* bpo-22485: Fixed an issue that caused "inspect.getsource" to return
  incorrect results on nested functions.

* bpo-22153: Improve unittest docs. Patch from Martin Panter and
  evilzero.

* bpo-24580: Symbolic group references to open group in re patterns
  now are explicitly forbidden as well as numeric group references.

* bpo-24206: Fixed __eq__ and __ne__ methods of inspect classes.

* bpo-24631: Fixed regression in the timeit module with multiline
  setup.

* bpo-18622: unittest.mock.mock_open().reset_mock would recurse
  infinitely. Patch from Nicola Palumbo and Laurent De Buyst.

* bpo-23661: unittest.mock side_effects can now be exceptions again.
  This was a regression vs Python 3.4. Patch from Ignacio Rossi

* bpo-24608: chunk.Chunk.read() now always returns bytes, not str.

* bpo-18684: Fixed reading out of the buffer in the re module.

* bpo-24259: tarfile now raises a ReadError if an archive is truncated
  inside a data segment.

* bpo-15014: SMTP.auth() and SMTP.login() now support RFC 4954’s
  optional initial-response argument to the SMTP AUTH command.

* bpo-24669: Fix inspect.getsource() for ‘async def’ functions. Patch
  by Kai Groner.

* bpo-24688: ast.get_docstring() for ‘async def’ functions.


Build
-----

* bpo-24603: Update Windows builds and OS X 10.5 installer to use
  OpenSSL 1.0.2d.


Python 3.5.0 beta 3
===================

*Release date: 2015-07-05*


Core and Builtins
-----------------

* bpo-24467: Fixed possible buffer over-read in bytearray. The
  bytearray object now always allocates place for trailing null byte
  and it’s buffer now is always null-terminated.

* Upgrade to Unicode 8.0.0.

* bpo-24345: Add Py_tp_finalize slot for the stable ABI.

* bpo-24400: Introduce a distinct type for **PEP 492** coroutines; add
  types.CoroutineType, inspect.getcoroutinestate,
  inspect.getcoroutinelocals; coroutines no longer use CO_GENERATOR
  flag; sys.set_coroutine_wrapper works only for ‘async def’
  coroutines; inspect.iscoroutine no longer uses
  collections.abc.Coroutine, it’s intended to test for pure ‘async
  def’ coroutines only; add new opcode: GET_YIELD_FROM_ITER; fix
  generators wrapper used in types.coroutine to be instance of
  collections.abc.Generator; collections.abc.Awaitable and
  collections.abc.Coroutine can no longer be used to detect generator-
  based coroutines–use inspect.isawaitable instead.

* bpo-24450: Add gi_yieldfrom to generators and cr_await to
  coroutines. Contributed by Benno Leslie and Yury Selivanov.

* bpo-19235: Add new RecursionError exception. Patch by Georg Brandl.


Library
-------

* bpo-21750: mock_open.read_data can now be read from each instance,
  as it could in Python 3.3.

* bpo-24552: Fix use after free in an error case of the _pickle
  module.

* bpo-24514: tarfile now tolerates number fields consisting of only
  whitespace.

* bpo-19176: Fixed doctype() related bugs in C implementation of
  ElementTree. A deprecation warning no longer issued by XMLParser
  subclass with default doctype() method.  Direct call of doctype()
  now issues a warning.  Parser’s doctype() now is not called if
  target’s doctype() is called.  Based on patch by Martin Panter.

* bpo-20387: Restore semantic round-trip correctness in
  tokenize/untokenize for tab-indented blocks.

* bpo-24456: Fixed possible buffer over-read in adpcm2lin() and
  lin2adpcm() functions of the audioop module.

* bpo-24336: The contextmanager decorator now works with functions
  with keyword arguments called “func” and “self”.  Patch by Martin
  Panter.

* bpo-24522: Fix possible integer overflow in json accelerator module.

* bpo-24489: ensure a previously set C errno doesn’t disturb
  cmath.polar().

* bpo-24408: Fixed AttributeError in measure() and metrics() methods
  of tkinter.Font.

* bpo-14373: C implementation of functools.lru_cache() now can be used
  with methods.

* bpo-24347: Set KeyError if PyDict_GetItemWithError returns NULL.

* bpo-24348: Drop superfluous incref/decref.

* bpo-24359: Check for changed OrderedDict size during iteration.

* bpo-24368: Support keyword arguments in OrderedDict methods.

* bpo-24362: Simplify the C OrderedDict fast nodes resize logic.

* bpo-24377: Fix a ref leak in OrderedDict.__repr__.

* bpo-24369: Defend against key-changes during iteration.


Tests
-----

* bpo-24373: _testmultiphase and xxlimited now use tp_traverse and
  tp_finalize to avoid reference leaks encountered when combining
  tp_dealloc with PyType_FromSpec (see bpo-16690 for details)


Documentation
-------------

* bpo-24458: Update documentation to cover multi-phase initialization
  for extension modules (PEP 489). Patch by Petr Viktorin.

* bpo-24351: Clarify what is meant by “identifier” in the context of
  string.Template instances.


Build
-----

* bpo-24432: Update Windows builds and OS X 10.5 installer to use
  OpenSSL 1.0.2c.


Python 3.5.0 beta 2
===================

*Release date: 2015-05-31*


Core and Builtins
-----------------

* bpo-24284: The startswith and endswith methods of the str class no
  longer return True when finding the empty string and the indexes are
  completely out of range.

* bpo-24115: Update uses of PyObject_IsTrue(), PyObject_Not(),
  PyObject_IsInstance(), PyObject_RichCompareBool() and
  _PyDict_Contains() to check for and handle errors correctly.

* bpo-24328: Fix importing one character extension modules.

* bpo-11205: In dictionary displays, evaluate the key before the
  value.

* bpo-24285: Fixed regression that prevented importing extension
  modules from inside packages. Patch by Petr Viktorin.


Library
-------

* bpo-23247: Fix a crash in the StreamWriter.reset() of CJK codecs.

* bpo-24270: Add math.isclose() and cmath.isclose() functions as per
  **PEP 485**. Contributed by Chris Barker and Tal Einat.

* bpo-5633: Fixed timeit when the statement is a string and the setup
  is not.

* bpo-24326: Fixed audioop.ratecv() with non-default weightB argument.
  Original patch by David Moore.

* bpo-16991: Add a C implementation of OrderedDict.

* bpo-23934: Fix inspect.signature to fail correctly for builtin types
  lacking signature information.  Initial patch by James Powell.


Python 3.5.0 beta 1
===================

*Release date: 2015-05-24*


Core and Builtins
-----------------

* bpo-24276: Fixed optimization of property descriptor getter.

* bpo-24268: PEP 489: Multi-phase extension module initialization.
  Patch by Petr Viktorin.

* bpo-23955: Add pyvenv.cfg option to suppress registry/environment
  lookup for generating sys.path on Windows.

* bpo-24257: Fixed system error in the comparison of faked
  types.SimpleNamespace.

* bpo-22939: Fixed integer overflow in iterator object.  Patch by
  Clement Rouault.

* bpo-23985: Fix a possible buffer overrun when deleting a slice from
  the front of a bytearray and then appending some other bytes data.

* bpo-24102: Fixed exception type checking in standard error handlers.

* bpo-15027: The UTF-32 encoder is now 3x to 7x faster.

* bpo-23290: Optimize set_merge() for cases where the target is empty.
  (Contributed by Serhiy Storchaka.)

* bpo-2292: PEP 448: Additional Unpacking Generalizations.

* bpo-24096: Make warnings.warn_explicit more robust against mutation
  of the warnings.filters list.

* bpo-23996: Avoid a crash when a delegated generator raises an
  unnormalized StopIteration exception.  Patch by Stefan Behnel.

* bpo-23910: Optimize property() getter calls.  Patch by Joe Jevnik.

* bpo-23911: Move path-based importlib bootstrap code to a separate
  frozen module.

* bpo-24192: Fix namespace package imports.

* bpo-24022: Fix tokenizer crash when processing undecodable source
  code.

* bpo-9951: Added a hex() method to bytes, bytearray, and memoryview.

* bpo-22906: PEP 479: Change StopIteration handling inside generators.

* bpo-24017: PEP 492: Coroutines with async and await syntax.


Library
-------

* bpo-14373: Added C implementation of functools.lru_cache().  Based
  on patches by Matt Joiner and Alexey Kachayev.

* bpo-24230: The tempfile module now accepts bytes for prefix, suffix
  and dir parameters and returns bytes in such situations (matching
  the os module APIs).

* bpo-22189: collections.UserString now supports __getnewargs__(),
  __rmod__(), casefold(), format_map(), isprintable(), and
  maketrans(). Patch by Joe Jevnik.

* bpo-24244: Prevents termination when an invalid format string is
  encountered on Windows in strftime.

* bpo-23973: PEP 484: Add the typing module.

* bpo-23086: The collections.abc.Sequence() abstract base class added
  *start* and *stop* parameters to the index() mixin. Patch by Devin
  Jeanpierre.

* bpo-20035: Replaced the "tkinter._fix" module used for setting up
  the Tcl/Tk environment on Windows with a private function in the
  "_tkinter" module that makes no permanent changes to the
  environment.

* bpo-24257: Fixed segmentation fault in sqlite3.Row constructor with
  faked cursor type.

* bpo-15836: assertRaises(), assertRaisesRegex(), assertWarns() and
  assertWarnsRegex() assertments now check the type of the first
  argument to prevent possible user error.  Based on patch by Daniel
  Wagner-Hall.

* bpo-9858: Add missing method stubs to _io.RawIOBase.  Patch by Laura
  Rupprecht.

* bpo-22955: attrgetter, itemgetter and methodcaller objects in the
  operator module now support pickling.  Added readable and evaluable
  repr for these objects. Based on patch by Josh Rosenberg.

* bpo-22107: tempfile.gettempdir() and tempfile.mkdtemp() now try
  again when a directory with the chosen name already exists on
  Windows as well as on Unix. tempfile.mkstemp() now fails early if
  parent directory is not valid (not exists or is a file) on Windows.

* bpo-23780: Improved error message in os.path.join() with single
  argument.

* bpo-6598: Increased time precision and random number range in
  email.utils.make_msgid() to strengthen the uniqueness of the message
  ID.

* bpo-24091: Fixed various crashes in corner cases in C implementation
  of ElementTree.

* bpo-21931: msilib.FCICreate() now raises TypeError in the case of a
  bad argument instead of a ValueError with a bogus FCI error number.
  Patch by Jeffrey Armstrong.

* bpo-13866: *quote_via* argument added to urllib.parse.urlencode.

* bpo-20098: New mangle_from policy option for email, default True for
  compat32, but False for all other policies.

* bpo-24211: The email library now supports RFC 6532: it can generate
  headers using utf-8 instead of encoded words.

* bpo-16314: Added support for the LZMA compression in distutils.

* bpo-21804: poplib now supports RFC 6856 (UTF8).

* bpo-18682: Optimized pprint functions for builtin scalar types.

* bpo-22027: smtplib now supports RFC 6531 (SMTPUTF8).

* bpo-23488: Random generator objects now consume 2x less memory on
  64-bit.

* bpo-1322: platform.dist() and platform.linux_distribution()
  functions are now deprecated.  Initial patch by Vajrasky Kok.

* bpo-22486: Added the math.gcd() function.  The fractions.gcd()
  function now is deprecated.  Based on patch by Mark Dickinson.

* bpo-24064: Property() docstrings are now writeable. (Patch by Berker
  Peksag.)

* bpo-22681: Added support for the koi8_t encoding.

* bpo-22682: Added support for the kz1048 encoding.

* bpo-23796: peek and read1 methods of BufferedReader now raise
  ValueError if they called on a closed object. Patch by John
  Hergenroeder.

* bpo-21795: smtpd now supports the 8BITMIME extension whenever the
  new *decode_data* constructor argument is set to False.

* bpo-24155: optimize heapq.heapify() for better cache performance
  when heapifying large lists.

* bpo-21800: imaplib now supports RFC 5161 (enable), RFC 6855
  (utf8/internationalized email) and automatically encodes non-ASCII
  usernames and passwords to UTF8.

* bpo-20274: When calling a _sqlite.Connection, it now complains if
  passed any keyword arguments.  Previously it silently ignored them.

* bpo-20274: Remove ignored and erroneous “kwargs” parameters from
  three METH_VARARGS methods on _sqlite.Connection.

* bpo-24134: assertRaises(), assertRaisesRegex(), assertWarns() and
  assertWarnsRegex() checks now emits a deprecation warning when
  callable is None or keyword arguments except msg is passed in the
  context manager mode.

* bpo-24018: Add a collections.abc.Generator abstract base class.
  Contributed by Stefan Behnel.

* bpo-23880: Tkinter’s getint() and getdouble() now support Tcl_Obj.
  Tkinter’s getdouble() now supports any numbers (in particular int).

* bpo-22619: Added negative limit support in the traceback module.
  Based on patch by Dmitry Kazakov.

* bpo-24094: Fix possible crash in json.encode with poorly behaved
  dict subclasses.

* bpo-9246: On POSIX, os.getcwd() now supports paths longer than 1025
  bytes. Patch written by William Orr.

* bpo-17445: add difflib.diff_bytes() to support comparison of byte
  strings (fixes a regression from Python 2).

* bpo-23917: Fall back to sequential compilation when
  ProcessPoolExecutor doesn’t exist. Patch by Claudiu Popa.

* bpo-23008: Fixed resolving attributes with boolean value is False in
  pydoc.

* Fix asyncio issue 235: LifoQueue and PriorityQueue’s put didn’t
  increment unfinished tasks (this bug was introduced when
  JoinableQueue was merged with Queue).

* bpo-23908: os functions now reject paths with embedded null
  character on Windows instead of silently truncating them.

* bpo-23728: binascii.crc_hqx() could return an integer outside of the
  range 0-0xffff for empty data.

* bpo-23887: urllib.error.HTTPError now has a proper repr()
  representation. Patch by Berker Peksag.

* asyncio: New event loop APIs: set_task_factory() and
  get_task_factory().

* asyncio: async() function is deprecated in favour of
  ensure_future().

* bpo-24178: asyncio.Lock, Condition, Semaphore, and BoundedSemaphore
  support new ‘async with’ syntax.  Contributed by Yury Selivanov.

* bpo-24179: Support ‘async for’ for asyncio.StreamReader. Contributed
  by Yury Selivanov.

* bpo-24184: Add AsyncIterator and AsyncIterable ABCs to
  collections.abc. Contributed by Yury Selivanov.

* bpo-22547: Implement informative __repr__ for
  inspect.BoundArguments. Contributed by Yury Selivanov.

* bpo-24190: Implement inspect.BoundArgument.apply_defaults() method.
  Contributed by Yury Selivanov.

* bpo-20691: Add ‘follow_wrapped’ argument to
  inspect.Signature.from_callable() and inspect.signature().
  Contributed by Yury Selivanov.

* bpo-24248: Deprecate inspect.Signature.from_function() and
  inspect.Signature.from_builtin().

* bpo-23898: Fix inspect.classify_class_attrs() to support attributes
  with overloaded __eq__ and __bool__.  Patch by Mike Bayer.

* bpo-24298: Fix inspect.signature() to correctly unwrap wrappers
  around bound methods.


IDLE
----

* bpo-23184: remove unused names and imports in idlelib. Initial patch
  by Al Sweigart.


Tests
-----

* bpo-21520: test_zipfile no longer fails if the word ‘bad’ appears
  anywhere in the name of the current directory.

* bpo-9517: Move script_helper into the support package. Patch by
  Christie Wilson.


Documentation
-------------

* bpo-22155: Add File Handlers subsection with createfilehandler to
  tkinter doc.  Remove obsolete example from FAQ.  Patch by Martin
  Panter.

* bpo-24029: Document the name binding behavior for submodule imports.

* bpo-24077: Fix typo in man page for -I command option: -s, not -S


Tools/Demos
-----------

* bpo-24000: Improved Argument Clinic’s mapping of converters to
  legacy “format units”. Updated the documentation to match.

* bpo-24001: Argument Clinic converters now use accept={type} instead
  of types={‘type’} to specify the types the converter accepts.

* bpo-23330: h2py now supports arbitrary filenames in #include.

* bpo-24031: make patchcheck now supports git checkouts, too.


Python 3.5.0 alpha 4
====================

*Release date: 2015-04-19*


Core and Builtins
-----------------

* bpo-22980: Under Linux, GNU/KFreeBSD and the Hurd, C extensions now
  include the architecture triplet in the extension name, to make it
  easy to test builds for different ABIs in the same working tree.
  Under OS X, the extension name now includes **PEP 3149**-style
  information.

* bpo-22631: Added Linux-specific socket constant CAN_RAW_FD_FRAMES.
  Patch courtesy of Joe Jevnik.

* bpo-23731: Implement **PEP 488**: removal of .pyo files.

* bpo-23726: Don’t enable GC for user subclasses of non-GC types that
  don’t add any new fields.  Patch by Eugene Toder.

* bpo-23309: Avoid a deadlock at shutdown if a daemon thread is
  aborted while it is holding a lock to a buffered I/O object, and the
  main thread tries to use the same I/O object (typically stdout or
  stderr).  A fatal error is emitted instead.

* bpo-22977: Fixed formatting Windows error messages on Wine. Patch by
  Martin Panter.

* bpo-23466: %c, %o, %x, and %X in bytes formatting now raise
  TypeError on non-integer input.

* bpo-24044: Fix possible null pointer dereference in list.sort in out
  of memory conditions.

* bpo-21354: PyCFunction_New function is exposed by python DLL again.


Library
-------

* bpo-23840: tokenize.open() now closes the temporary binary file on
  error to fix a resource warning.

* bpo-16914: new debuglevel 2 in smtplib adds timestamps to debug
  output.

* bpo-7159: urllib.request now supports sending auth credentials
  automatically after the first 401.  This enhancement is a superset
  of the enhancement from bpo-19494 and supersedes that change.

* bpo-23703: Fix a regression in urljoin() introduced in 901e4e52b20a.
  Patch by Demian Brecht.

* bpo-4254: Adds _curses.update_lines_cols().  Patch by Arnon Yaari

* bpo-19933: Provide default argument for ndigits in round. Patch by
  Vajrasky Kok.

* bpo-23193: Add a numeric_owner parameter to tarfile.TarFile.extract
  and tarfile.TarFile.extractall. Patch by Michael Vogt and Eric
  Smith.

* bpo-23342: Add a subprocess.run() function than returns a
  CalledProcess instance for a more consistent API than the existing
  call* functions.

* bpo-21217: inspect.getsourcelines() now tries to compute the start
  and end lines from the code object, fixing an issue when a lambda
  function is used as decorator argument. Patch by Thomas Ballinger
  and Allison Kaptur.

* bpo-24521: Fix possible integer overflows in the pickle module.

* bpo-22931: Allow ‘[’ and ‘]’ in cookie values.

* The keywords attribute of functools.partial is now always a
  dictionary.

* bpo-23811: Add missing newline to the PyCompileError error message.
  Patch by Alex Shkop.

* bpo-21116: Avoid blowing memory when allocating a multiprocessing
  shared array that’s larger than 50% of the available RAM.  Patch by
  Médéric Boquien.

* bpo-22982: Improve BOM handling when seeking to multiple positions
  of a writable text file.

* bpo-23464: Removed deprecated asyncio JoinableQueue.

* bpo-23529: Limit the size of decompressed data when reading from
  GzipFile, BZ2File or LZMAFile.  This defeats denial of service
  attacks using compressed bombs (i.e. compressed payloads which
  decompress to a huge size).  Patch by Martin Panter and Nikolaus
  Rath.

* bpo-21859: Added Python implementation of io.FileIO.

* bpo-23865: close() methods in multiple modules now are idempotent
  and more robust at shutdown. If they need to release multiple
  resources, all are released even if errors occur.

* bpo-23400: Raise same exception on both Python 2 and 3 if sem_open
  is not available. Patch by Davin Potts.

* bpo-10838: The subprocess now module includes SubprocessError and
  TimeoutError in its list of exported names for the users wild enough
  to use "from subprocess import *".

* bpo-23411: Added DefragResult, ParseResult, SplitResult,
  DefragResultBytes, ParseResultBytes, and SplitResultBytes to
  urllib.parse.__all__. Patch by Martin Panter.

* bpo-23881: urllib.request.ftpwrapper constructor now closes the
  socket if the FTP connection failed to fix a ResourceWarning.

* bpo-23853: "socket.socket.sendall()" does no more reset the socket
  timeout each time data is sent successfully. The socket timeout is
  now the maximum total duration to send all data.

* bpo-22721: An order of multiline pprint output of set or dict
  containing orderable and non-orderable elements no longer depends on
  iteration order of set or dict.

* bpo-15133: _tkinter.tkapp.getboolean() now supports Tcl_Obj and
  always returns bool. tkinter.BooleanVar now validates input values
  (accepted bool, int, str, and Tcl_Obj).  tkinter.BooleanVar.get()
  now always returns bool.

* bpo-10590: xml.sax.parseString() now supports string argument.

* bpo-23338: Fixed formatting ctypes error messages on Cygwin. Patch
  by Makoto Kato.

* bpo-15582: inspect.getdoc() now follows inheritance chains.

* bpo-2175: SAX parsers now support a character stream of InputSource
  object.

* bpo-16840: Tkinter now supports 64-bit integers added in Tcl 8.4 and
  arbitrary precision integers added in Tcl 8.5.

* bpo-23834: Fix socket.sendto(), use the C Py_ssize_t type to store
  the result of sendto() instead of the C int type.

* bpo-23618: "socket.socket.connect()" now waits until the connection
  completes instead of raising "InterruptedError" if the connection is
  interrupted by signals, signal handlers don’t raise an exception and
  the socket is blocking or has a timeout. "socket.socket.connect()"
  still raise "InterruptedError" for non-blocking sockets.

* bpo-21526: Tkinter now supports new boolean type in Tcl 8.5.

* bpo-23836: Fix the faulthandler module to handle reentrant calls to
  its signal handlers.

* bpo-23838: linecache now clears the cache and returns an empty
  result on MemoryError.

* bpo-10395: Added os.path.commonpath(). Implemented in posixpath and
  ntpath. Based on patch by Rafik Draoui.

* bpo-23611: Serializing more “lookupable” objects (such as unbound
  methods or nested classes) now are supported with pickle protocols <
  4.

* bpo-13583: sqlite3.Row now supports slice indexing.

* bpo-18473: Fixed 2to3 and 3to2 compatible pickle mappings.  Fixed
  ambiguous reverse mappings.  Added many new mappings.  Import
  mapping is no longer applied to modules already mapped with full
  name mapping.

* bpo-23485: select.select() is now retried automatically with the
  recomputed timeout when interrupted by a signal, except if the
  signal handler raises an exception. This change is part of the **PEP
  475**.

* bpo-23752: When built from an existing file descriptor, io.FileIO()
  now only calls fstat() once. Before fstat() was called twice, which
  was not necessary.

* bpo-23704: collections.deque() objects now support __add__, __mul__,
  and __imul__().

* bpo-23171: csv.Writer.writerow() now supports arbitrary iterables.

* bpo-23745: The new email header parser now handles duplicate MIME
  parameter names without error, similar to how get_param behaves.

* bpo-22117: Fix os.utime(), it now rounds the timestamp towards minus
  infinity (-inf) instead of rounding towards zero.

* bpo-23310: Fix MagicMock’s initializer to work with __methods__,
  just like configure_mock().  Patch by Kasia Jachim.


Build
-----

* bpo-23817: FreeBSD now uses “1.0” in the SOVERSION as other
  operating systems, instead of just “1”.

* bpo-23501: Argument Clinic now generates code into separate files by
  default.


Tests
-----

* bpo-23799: Added test.support.start_threads() for running and
  cleaning up multiple threads.

* bpo-22390: test.regrtest now emits a warning if temporary files or
  directories are left after running a test.


Tools/Demos
-----------

* bpo-18128: pygettext now uses standard +NNNN format in the POT-
  Creation-Date header.

* bpo-23935: Argument Clinic’s understanding of format units accepting
  bytes, bytearrays, and buffers is now consistent with both the
  documentation and the implementation.

* bpo-23944: Argument Clinic now wraps long impl prototypes at column
  78.

* bpo-20586: Argument Clinic now ensures that functions without
  docstrings have signatures.

* bpo-23492: Argument Clinic now generates argument parsing code with
  PyArg_Parse instead of PyArg_ParseTuple if possible.

* bpo-23500: Argument Clinic is now smarter about generating the
  “#ifndef” (empty) definition of the methoddef macro: it’s only
  generated once, even if Argument Clinic processes the same symbol
  multiple times, and it’s emitted at the end of all processing rather
  than immediately after the first use.


C API
-----

* bpo-23998: PyImport_ReInitLock() now checks for lock allocation
  error


Python 3.5.0 alpha 3
====================

*Release date: 2015-03-28*


Core and Builtins
-----------------

* bpo-23573: Increased performance of string search operations
  (str.find, str.index, str.count, the in operator, str.split,
  str.partition) with arguments of different kinds (UCS1, UCS2, UCS4).

* bpo-23753: Python doesn’t support anymore platforms without stat()
  or fstat(), these functions are always required.

* bpo-23681: The -b option now affects comparisons of bytes with int.

* bpo-23632: Memoryviews now allow tuple indexing (including for
  multi-dimensional memoryviews).

* bpo-23192: Fixed generator lambdas.  Patch by Bruno Cauet.

* bpo-23629: Fix the default __sizeof__ implementation for variable-
  sized objects.


Library
-------

* bpo-14260: The groupindex attribute of regular expression pattern
  object now is non-modifiable mapping.

* bpo-23792: Ignore KeyboardInterrupt when the pydoc pager is active.
  This mimics the behavior of the standard unix pagers, and prevents
  pipepager from shutting down while the pager itself is still
  running.

* bpo-23775: pprint() of OrderedDict now outputs the same
  representation as repr().

* bpo-23765: Removed IsBadStringPtr calls in ctypes

* bpo-22364: Improved some re error messages using regex for hints.

* bpo-23742: ntpath.expandvars() no longer loses unbalanced single
  quotes.

* bpo-21717: The zipfile.ZipFile.open function now supports ‘x’
  (exclusive creation) mode.

* bpo-21802: The reader in BufferedRWPair now is closed even when
  closing writer failed in BufferedRWPair.close().

* bpo-23622: Unknown escapes in regular expressions that consist of
  "'\'" and ASCII letter now raise a deprecation warning and will be
  forbidden in Python 3.6.

* bpo-23671: string.Template now allows specifying the “self”
  parameter as a keyword argument.  string.Formatter now allows
  specifying the “self” and the “format_string” parameters as keyword
  arguments.

* bpo-23502: The pprint module now supports mapping proxies.

* bpo-17530: pprint now wraps long bytes objects and bytearrays.

* bpo-22687: Fixed some corner cases in breaking words in tetxtwrap.
  Got rid of quadratic complexity in breaking long words.

* bpo-4727: The copy module now uses pickle protocol 4 (PEP 3154) and
  supports copying of instances of classes whose __new__ method takes
  keyword-only arguments.

* bpo-23491: Added a zipapp module to support creating executable zip
  file archives of Python code. Registered “.pyz” and “.pyzw”
  extensions on Windows for these archives (PEP 441).

* bpo-23657: Avoid explicit checks for str in zipapp, adding support
  for pathlib.Path objects as arguments.

* bpo-23688: Added support of arbitrary bytes-like objects and avoided
  unnecessary copying of memoryview in gzip.GzipFile.write(). Original
  patch by Wolfgang Maier.

* bpo-23252: Added support for writing ZIP files to unseekable
  streams.

* bpo-23647: Increase imaplib’s MAXLINE to accommodate modern mailbox
  sizes.

* bpo-23539: If body is None, http.client.HTTPConnection.request now
  sets Content-Length to 0 for PUT, POST, and PATCH headers to avoid
  411 errors from some web servers.

* bpo-22351: The nntplib.NNTP constructor no longer leaves the
  connection and socket open until the garbage collector cleans them
  up.  Patch by Martin Panter.

* bpo-23704: collections.deque() objects now support methods for
  index(), insert(), and copy().  This allows deques to be registered
  as a MutableSequence and it improves their substitutability for
  lists.

* bpo-23715: "signal.sigwaitinfo()" and "signal.sigtimedwait()" are
  now retried when interrupted by a signal not in the *sigset*
  parameter, if the signal handler does not raise an exception.
  signal.sigtimedwait() recomputes the timeout with a monotonic clock
  when it is retried.

* bpo-23001: Few functions in modules mmap, ossaudiodev, socket, ssl,
  and codecs, that accepted only read-only bytes-like object now
  accept writable bytes-like object too.

* bpo-23646: If time.sleep() is interrupted by a signal, the sleep is
  now retried with the recomputed delay, except if the signal handler
  raises an exception (PEP 475).

* bpo-23136: _strptime now uniformly handles all days in week 0,
  including Dec 30 of previous year.  Based on patch by Jim Carroll.

* bpo-23700: Iterator of NamedTemporaryFile now keeps a reference to
  NamedTemporaryFile instance.  Patch by Bohuslav Kabrda.

* bpo-22903: The fake test case created by unittest.loader when it
  fails importing a test module is now picklable.

* bpo-22181: On Linux, os.urandom() now uses the new getrandom()
  syscall if available, syscall introduced in the Linux kernel 3.17.
  It is more reliable and more secure, because it avoids the need of a
  file descriptor and waits until the kernel has enough entropy.

* bpo-2211: Updated the implementation of the http.cookies.Morsel
  class. Setting attributes key, value and coded_value directly now is
  deprecated. update() and setdefault() now transform and check keys.
  Comparing for equality now takes into account attributes key, value
  and coded_value. copy() now returns a Morsel, not a dict.  repr()
  now contains all attributes. Optimized checking keys and quoting
  values.  Added new tests. Original patch by Demian Brecht.

* bpo-18983: Allow selection of output units in timeit. Patch by
  Julian Gindi.

* bpo-23631: Fix traceback.format_list when a traceback has been
  mutated.

* bpo-23568: Add rdivmod support to MagicMock() objects. Patch by
  Håkan Lövdahl.

* bpo-2052: Add charset parameter to HtmlDiff.make_file().

* bpo-23668: Support os.truncate and os.ftruncate on Windows.

* bpo-23138: Fixed parsing cookies with absent keys or values in
  cookiejar. Patch by Demian Brecht.

* bpo-23051: multiprocessing.Pool methods imap() and imap_unordered()
  now handle exceptions raised by an iterator.  Patch by Alon Diamant
  and Davin Potts.

* bpo-23581: Add matmul support to MagicMock. Patch by Håkan Lövdahl.

* bpo-23566: enable(), register(), dump_traceback() and
  dump_traceback_later() functions of faulthandler now accept file
  descriptors. Patch by Wei Wu.

* bpo-22928: Disabled HTTP header injections in http.client. Original
  patch by Demian Brecht.

* bpo-23615: Modules bz2, tarfile and tokenize now can be reloaded
  with imp.reload(). Patch by Thomas Kluyver.

* bpo-23605: os.walk() now calls os.scandir() instead of os.listdir().
  The usage of os.scandir() reduces the number of calls to os.stat().
  Initial patch written by Ben Hoyt.


Build
-----

* bpo-23585: make patchcheck will ensure the interpreter is built.


Tests
-----

* bpo-23583: Added tests for standard IO streams in IDLE.

* bpo-22289: Prevent test_urllib2net failures due to ftp connection
  timeout.


Tools/Demos
-----------

* bpo-22826: The result of open() in Tools/freeze/bkfile.py is now
  better compatible with regular files (in particular it now supports
  the context management protocol).


Python 3.5.0 alpha 2
====================

*Release date: 2015-03-09*


Core and Builtins
-----------------

* bpo-23571: PyObject_Call() and PyCFunction_Call() now raise a
  SystemError if a function returns a result and raises an exception.
  The SystemError is chained to the previous exception.


Library
-------

* bpo-22524: New os.scandir() function, part of the **PEP 471**:
  “os.scandir() function – a better and faster directory iterator”.
  Patch written by Ben Hoyt.

* bpo-23103: Reduced the memory consumption of IPv4Address and
  IPv6Address.

* bpo-21793: BaseHTTPRequestHandler again logs response code as
  numeric, not as stringified enum.  Patch by Demian Brecht.

* bpo-23476: In the ssl module, enable OpenSSL’s
  X509_V_FLAG_TRUSTED_FIRST flag on certificate stores when it is
  available.

* bpo-23576: Avoid stalling in SSL reads when EOF has been reached in
  the SSL layer but the underlying connection hasn’t been closed.

* bpo-23504: Added an __all__ to the types module.

* bpo-23563: Optimized utility functions in urllib.parse.

* bpo-7830: Flatten nested functools.partial.

* bpo-20204: Added the __module__ attribute to _tkinter classes.

* bpo-19980: Improved help() for non-recognized strings.  help(‘’) now
  shows the help on str.  help(‘help’) now shows the help on help().
  Original patch by Mark Lawrence.

* bpo-23521: Corrected pure python implementation of timedelta
  division. Eliminated OverflowError from "timedelta * float" for some
  floats; Corrected rounding in timedelta true division.

* bpo-21619: Popen objects no longer leave a zombie after exit in the
  with statement if the pipe was broken.  Patch by Martin Panter.

* bpo-22936: Make it possible to show local variables in tracebacks
  for both the traceback module and unittest.

* bpo-15955: Add an option to limit the output size in
  bz2.decompress(). Patch by Nikolaus Rath.

* bpo-6639: Module-level turtle functions no longer raise TclError
  after closing the window.

* bpo-814253: Group references and conditional group references now
  work in lookbehind assertions in regular expressions. (See also:
  bpo-9179)

* bpo-23215: Multibyte codecs with custom error handlers that ignores
  errors consumed too much memory and raised SystemError or
  MemoryError. Original patch by Aleksi Torhamo.

* bpo-5700: io.FileIO() called flush() after closing the file. flush()
  was not called in close() if closefd=False.

* bpo-23374: Fixed pydoc failure with non-ASCII files when stdout
  encoding differs from file system encoding (e.g. on Mac OS).

* bpo-23481: Remove RC4 from the SSL module’s default cipher list.

* bpo-21548: Fix pydoc.synopsis() and pydoc.apropos() on modules with
  empty docstrings.

* bpo-22885: Fixed arbitrary code execution vulnerability in the
  dbm.dumb module. Original patch by Claudiu Popa.

* bpo-23239: ssl.match_hostname() now supports matching of IP
  addresses.

* bpo-23146: Fix mishandling of absolute Windows paths with forward
  slashes in pathlib.

* bpo-23096: Pickle representation of floats with protocol 0 now is
  the same for both Python and C implementations.

* bpo-19105: pprint now more efficiently uses free space at the right.

* bpo-14910: Add allow_abbrev parameter to argparse.ArgumentParser.
  Patch by Jonathan Paugh, Steven Bethard, paul j3 and Daniel
  Eriksson.

* bpo-21717: tarfile.open() now supports ‘x’ (exclusive creation)
  mode.

* bpo-23344: marshal.dumps() is now 20-25% faster on average.

* bpo-20416: marshal.dumps() with protocols 3 and 4 is now 40-50%
  faster on average.

* bpo-23421: Fixed compression in tarfile CLI.  Patch by wdv4758h.

* bpo-23367: Fix possible overflows in the unicodedata module.

* bpo-23361: Fix possible overflow in Windows subprocess creation
  code.

* logging.handlers.QueueListener now takes a respect_handler_level
  keyword argument which, if set to True, will pass messages to
  handlers taking handler levels into account.

* bpo-19705: turtledemo now has a visual sorting algorithm demo.
  Original patch from Jason Yeo.

* bpo-23801: Fix issue where cgi.FieldStorage did not always ignore
  the entire preamble to a multipart body.


Build
-----

* bpo-23445: pydebug builds now use “gcc -Og” where possible, to make
  the resulting executable faster.

* bpo-23686: Update OS X 10.5 installer build to use OpenSSL 1.0.2a.


C API
-----

* bpo-20204: Deprecation warning is now raised for builtin types
  without the __module__ attribute.


Windows
-------

* bpo-23465: Implement **PEP 486** - Make the Python Launcher aware of
  virtual environments. Patch by Paul Moore.

* bpo-23437: Make user scripts directory versioned on Windows. Patch
  by Paul Moore.


Python 3.5.0 alpha 1
====================

*Release date: 2015-02-08*


Core and Builtins
-----------------

* bpo-23285: PEP 475 - EINTR handling.

* bpo-22735: Fix many edge cases (including crashes) involving custom
  mro() implementations.

* bpo-22896: Avoid using PyObject_AsCharBuffer(),
  PyObject_AsReadBuffer() and PyObject_AsWriteBuffer().

* bpo-21295: Revert some changes (bpo-16795) to AST line numbers and
  column offsets that constituted a regression.

* bpo-22986: Allow changing an object’s __class__ between a dynamic
  type and static type in some cases.

* bpo-15859: PyUnicode_EncodeFSDefault(), PyUnicode_EncodeMBCS() and
  PyUnicode_EncodeCodePage() now raise an exception if the object is
  not a Unicode object. For PyUnicode_EncodeFSDefault(), it was
  already the case on platforms other than Windows. Patch written by
  Campbell Barton.

* bpo-21408: The default __ne__() now returns NotImplemented if
  __eq__() returned NotImplemented.  Original patch by Martin Panter.

* bpo-23321: Fixed a crash in str.decode() when error handler returned
  replacement string longer than malformed input data.

* bpo-22286: The “backslashreplace” error handlers now works with
  decoding and translating.

* bpo-23253: Delay-load ShellExecute[AW] in os.startfile for reduced
  startup overhead on Windows.

* bpo-22038: pyatomic.h now uses stdatomic.h or GCC built-in functions
  for atomic memory access if available. Patch written by Vitor de
  Lima and Gustavo Temple.

* bpo-20284: %-interpolation (aka printf) formatting added for bytes
  and bytearray.

* bpo-23048: Fix jumping out of an infinite while loop in the pdb.

* bpo-20335: bytes constructor now raises TypeError when encoding or
  errors is specified with non-string argument.  Based on patch by
  Renaud Blanch.

* bpo-22834: If the current working directory ends up being set to a
  non-existent directory then import will no longer raise
  FileNotFoundError.

* bpo-22869: Move the interpreter startup & shutdown code to a new
  dedicated pylifecycle.c module

* bpo-22847: Improve method cache efficiency.

* bpo-22335: Fix crash when trying to enlarge a bytearray to
  0x7fffffff bytes on a 32-bit platform.

* bpo-22653: Fix an assertion failure in debug mode when doing a
  reentrant dict insertion in debug mode.

* bpo-22643: Fix integer overflow in Unicode case operations (upper,
  lower, title, swapcase, casefold).

* bpo-17636: Circular imports involving relative imports are now
  supported.

* bpo-22604: Fix assertion error in debug mode when dividing a complex
  number by (nan+0j).

* bpo-21052: Do not raise ImportWarning when sys.path_hooks or
  sys.meta_path are set to None.

* bpo-16518: Use ‘bytes-like object required’ in error messages that
  previously used the far more cryptic “‘x’ does not support the
  buffer protocol.

* bpo-22470: Fixed integer overflow issues in “backslashreplace”,
  “xmlcharrefreplace”, and “surrogatepass” error handlers.

* bpo-22540: speed up "PyObject_IsInstance" and "PyObject_IsSubclass"
  in the common case that the second argument has metaclass "type".

* bpo-18711: Add a new "PyErr_FormatV" function, similar to
  "PyErr_Format" but accepting a "va_list" argument.

* bpo-22520: Fix overflow checking when generating the repr of a
  unicode object.

* bpo-22519: Fix overflow checking in PyBytes_Repr.

* bpo-22518: Fix integer overflow issues in latin-1 encoding.

* bpo-16324: _charset parameter of MIMEText now also accepts
  email.charset.Charset instances. Initial patch by Claude Paroz.

* bpo-1764286: Fix inspect.getsource() to support decorated functions.
  Patch by Claudiu Popa.

* bpo-18554: os.__all__ includes posix functions.

* bpo-21391: Use os.path.abspath in the shutil module.

* bpo-11471: avoid generating a JUMP_FORWARD instruction at the end of
  an if-block if there is no else-clause.  Original patch by Eugene
  Toder.

* bpo-22215: Now ValueError is raised instead of TypeError when str or
  bytes argument contains not permitted null character or byte.

* bpo-22258: Fix the internal function set_inheritable() on Illumos.
  This platform exposes the function "ioctl(FIOCLEX)", but calling it
  fails with errno is ENOTTY: “Inappropriate ioctl for device”.
  set_inheritable() now falls back to the slower "fcntl()" ("F_GETFD"
  and then "F_SETFD").

* bpo-21389: Displaying the __qualname__ of the underlying function in
  the repr of a bound method.

* bpo-22206: Using pthread, PyThread_create_key() now sets errno to
  ENOMEM and returns -1 (error) on integer overflow.

* bpo-20184: Argument Clinic based signature introspection added for
  30 of the builtin functions.

* bpo-22116: C functions and methods (of the
  ‘builtin_function_or_method’ type) can now be weakref’ed.  Patch by
  Wei Wu.

* bpo-22077: Improve index error messages for bytearrays, bytes,
  lists, and tuples by adding ‘or slices’. Added ‘, not <typename>’
  for bytearrays. Original patch by Claudiu Popa.

* bpo-20179: Apply Argument Clinic to bytes and bytearray. Patch by
  Tal Einat.

* bpo-22082: Clear interned strings in slotdefs.

* Upgrade Unicode database to Unicode 7.0.0.

* bpo-21897: Fix a crash with the f_locals attribute with closure
  variables when frame.clear() has been called.

* bpo-21205: Add a new "__qualname__" attribute to generator, the
  qualified name, and use it in the representation of a generator
  ("repr(gen)"). The default name of the generator ("__name__"
  attribute) is now get from the function instead of the code. Use
  "gen.gi_code.co_name" to get the name of the code.

* bpo-21669: With the aid of heuristics in SyntaxError.__init__, the
  parser now attempts to generate more meaningful (or at least more
  search engine friendly) error messages when “exec” and “print” are
  used as statements.

* bpo-21642: In the conditional if-else expression, allow an integer
  written with no space between itself and the "else" keyword (e.g.
  "True if 42else False") to be valid syntax.

* bpo-21523: Fix over-pessimistic computation of the stack effect of
  some opcodes in the compiler.  This also fixes a quadratic
  compilation time issue noticeable when compiling code with a large
  number of “and” and “or” operators.

* bpo-21418: Fix a crash in the builtin function super() when called
  without argument and without current frame (ex: embedded Python).

* bpo-21425: Fix flushing of standard streams in the interactive
  interpreter.

* bpo-21435: In rare cases, when running finalizers on objects in
  cyclic trash a bad pointer dereference could occur due to a subtle
  flaw in internal iteration logic.

* bpo-21377: PyBytes_Concat() now tries to concatenate in-place when
  the first argument has a reference count of 1.  Patch by Nikolaus
  Rath.

* bpo-20355: -W command line options now have higher priority than the
  PYTHONWARNINGS environment variable.  Patch by Arfrever.

* bpo-21274: Define PATH_MAX for GNU/Hurd in Python/pythonrun.c.

* bpo-20904: Support setting FPU precision on m68k.

* bpo-21209: Fix sending tuples to custom generator objects with the
  yield from syntax.

* bpo-21193: pow(a, b, c) now raises ValueError rather than TypeError
  when b is negative. Patch by Josh Rosenberg.

* bpo-21176: PEP 465: Add the ‘@’ operator for matrix multiplication.

* bpo-21134: Fix segfault when str is called on an uninitialized
  UnicodeEncodeError, UnicodeDecodeError, or UnicodeTranslateError
  object.

* bpo-19537: Fix PyUnicode_DATA() alignment under m68k.  Patch by
  Andreas Schwab.

* bpo-20929: Add a type cast to avoid shifting a negative number.

* bpo-20731: Properly position in source code files even if they are
  opened in text mode. Patch by Serhiy Storchaka.

* bpo-20637: Key-sharing now also works for instance dictionaries of
  subclasses.  Patch by Peter Ingebretson.

* bpo-8297: Attributes missing from modules now include the module
  name in the error text.  Original patch by ysj.ray.

* bpo-19995: %c, %o, %x, and %X now raise TypeError on non-integer
  input.

* bpo-19655: The ASDL parser - used by the build process to generate
  code for managing the Python AST in C - was rewritten. The new
  parser is self contained and does not require to carry long the
  spark.py parser-generator library; spark.py was removed from the
  source base.

* bpo-12546: Allow "\x00" to be used as a fill character when using
  str, int, float, and complex __format__ methods.

* bpo-20480: Add ipaddress.reverse_pointer. Patch by Leon Weber.

* bpo-13598: Modify string.Formatter to support auto-numbering of
  replacement fields. It now matches the behavior of str.format() in
  this regard. Patches by Phil Elson and Ramchandra Apte.

* bpo-8931: Make alternate formatting (‘#’) for type ‘c’ raise an
  exception. In versions prior to 3.5, ‘#’ with ‘c’ had no effect. Now
  specifying it is an error. Patch by Torsten Landschoff.

* bpo-23165: Perform overflow checks before allocating memory in the
  _Py_char2wchar function.


Library
-------

* bpo-23399: pyvenv creates relative symlinks where possible.

* bpo-20289: cgi.FieldStorage() now supports the context management
  protocol.

* bpo-13128: Print response headers for CONNECT requests when
  debuglevel > 0. Patch by Demian Brecht.

* bpo-15381: Optimized io.BytesIO to make less allocations and
  copyings.

* bpo-22818: Splitting on a pattern that could match an empty string
  now raises a warning.  Patterns that can only match empty strings
  are now rejected.

* bpo-23099: Closing io.BytesIO with exported buffer is rejected now
  to prevent corrupting exported buffer.

* bpo-23326: Removed __ne__ implementations.  Since fixing default
  __ne__ implementation in bpo-21408 they are redundant.

* bpo-23363: Fix possible overflow in itertools.permutations.

* bpo-23364: Fix possible overflow in itertools.product.

* bpo-23366: Fixed possible integer overflow in
  itertools.combinations.

* bpo-23369: Fixed possible integer overflow in
  _json.encode_basestring_ascii.

* bpo-23353: Fix the exception handling of generators in
  PyEval_EvalFrameEx(). At entry, save or swap the exception state
  even if PyEval_EvalFrameEx() is called with throwflag=0. At exit,
  the exception state is now always restored or swapped, not only if
  why is WHY_YIELD or WHY_RETURN. Patch co-written with Antoine
  Pitrou.

* bpo-14099: Restored support of writing ZIP files to tellable but
  non-seekable streams.

* bpo-14099: Writing to ZipFile and reading multiple ZipExtFiles is
  threadsafe now.

* bpo-19361: JSON decoder now raises JSONDecodeError instead of
  ValueError.

* bpo-18518: timeit now rejects statements which can’t be compiled
  outside a function or a loop (e.g. “return” or “break”).

* bpo-23094: Fixed readline with frames in Python implementation of
  pickle.

* bpo-23268: Fixed bugs in the comparison of ipaddress classes.

* bpo-21408: Removed incorrect implementations of __ne__() which
  didn’t returned NotImplemented if __eq__() returned NotImplemented.
  The default __ne__() now works correctly.

* bpo-19996: "email.feedparser.FeedParser" now handles (malformed)
  headers with no key rather than assuming the body has started.

* bpo-20188: Support Application-Layer Protocol Negotiation (ALPN) in
  the ssl module.

* bpo-23133: Pickling of ipaddress objects now produces more compact
  and portable representation.

* bpo-23248: Update ssl error codes from latest OpenSSL git master.

* bpo-23266: Much faster implementation of
  ipaddress.collapse_addresses() when there are many non-consecutive
  addresses.

* bpo-23098: 64-bit dev_t is now supported in the os module.

* bpo-21817: When an exception is raised in a task submitted to a
  ProcessPoolExecutor, the remote traceback is now displayed in the
  parent process.  Patch by Claudiu Popa.

* bpo-15955: Add an option to limit output size when decompressing
  LZMA data.  Patch by Nikolaus Rath and Martin Panter.

* bpo-23250: In the http.cookies module, capitalize “HttpOnly” and
  “Secure” as they are written in the standard.

* bpo-23063: In the distutils’ check command, fix parsing of reST with
  code or code-block directives.

* bpo-23209: selectors.BaseSelector.get_key() now raises a
  RuntimeError if the selector is closed. And
  selectors.BaseSelector.close() now clears its internal reference to
  the selector mapping to break a reference cycle. Initial patch
  written by Martin Richard. (See also: bpo-23225)

* bpo-17911: Provide a way to seed the linecache for a PEP-302 module
  without actually loading the code.

* bpo-17911: Provide a new object API for traceback, including the
  ability to not lookup lines at all until the traceback is actually
  rendered, without any trace of the original objects being kept
  alive.

* bpo-19777: Provide a home() classmethod on Path objects.
  Contributed by Victor Salgado and Mayank Tripathi.

* bpo-23206: Make "json.dumps(..., ensure_ascii=False)" as fast as the
  default case of "ensure_ascii=True".  Patch by Naoki Inada.

* bpo-23185: Add math.inf and math.nan constants.

* bpo-23186: Add ssl.SSLObject.shared_ciphers() and
  ssl.SSLSocket.shared_ciphers() to fetch the client’s list ciphers
  sent at handshake.

* bpo-23143: Remove compatibility with OpenSSLs older than 0.9.8.

* bpo-23132: Improve performance and introspection support of
  comparison methods created by functool.total_ordering.

* bpo-19776: Add an expanduser() method on Path objects.

* bpo-23112: Fix SimpleHTTPServer to correctly carry the query string
  and fragment when it redirects to add a trailing slash.

* bpo-21793: Added http.HTTPStatus enums (i.e. HTTPStatus.OK,
  HTTPStatus.NOT_FOUND). Patch by Demian Brecht.

* bpo-23093: In the io, module allow more operations to work on
  detached streams.

* bpo-23111: In the ftplib, make ssl.PROTOCOL_SSLv23 the default
  protocol version.

* bpo-22585: On OpenBSD 5.6 and newer, os.urandom() now calls
  getentropy(), instead of reading /dev/urandom, to get pseudo-random
  bytes.

* bpo-19104: pprint now produces evaluable output for wrapped strings.

* bpo-23071: Added missing names to codecs.__all__.  Patch by Martin
  Panter.

* bpo-22783: Pickling now uses the NEWOBJ opcode instead of the
  NEWOBJ_EX opcode if possible.

* bpo-15513: Added a __sizeof__ implementation for pickle classes.

* bpo-19858: pickletools.optimize() now aware of the MEMOIZE opcode,
  can produce more compact result and no longer produces invalid
  output if input data contains MEMOIZE opcodes together with PUT or
  BINPUT opcodes.

* bpo-22095: Fixed HTTPConnection.set_tunnel with default port.  The
  port value in the host header was set to “None”.  Patch by Demian
  Brecht.

* bpo-23016: A warning no longer produces an AttributeError when the
  program is run with pythonw.exe.

* bpo-21775: shutil.copytree(): fix crash when copying to VFAT. An
  exception handler assumed that OSError objects always have a
  ‘winerror’ attribute. That is not the case, so the exception handler
  itself raised AttributeError when run on Linux (and, presumably, any
  other non-Windows OS). Patch by Greg Ward.

* bpo-1218234: Fix inspect.getsource() to load updated source of
  reloaded module. Initial patch by Berker Peksag.

* bpo-21740: Support wrapped callables in doctest. Patch by Claudiu
  Popa.

* bpo-23009: Make sure selectors.EpollSelector.select() works when no
  FD is registered.

* bpo-22959: In the constructor of http.client.HTTPSConnection, prefer
  the context’s check_hostname attribute over the *check_hostname*
  parameter.

* bpo-22696: Add function "sys.is_finalizing()" to know about
  interpreter shutdown.

* bpo-16043: Add a default limit for the amount of data
  xmlrpclib.gzip_decode will return. This resolves CVE-2013-1753.

* bpo-14099: ZipFile.open() no longer reopen the underlying file.
  Objects returned by ZipFile.open() can now operate independently of
  the ZipFile even if the ZipFile was created by passing in a file-
  like object as the first argument to the constructor.

* bpo-22966: Fix __pycache__ pyc file name clobber when pyc_compile is
  asked to compile a source file containing multiple dots in the
  source file name.

* bpo-21971: Update turtledemo doc and add module to the index.

* bpo-21032: Fixed socket leak if HTTPConnection.getresponse() fails.
  Original patch by Martin Panter.

* bpo-22407: Deprecated the use of re.LOCALE flag with str patterns or
  re.ASCII. It was newer worked.

* bpo-22902: The “ip” command is now used on Linux to determine MAC
  address in uuid.getnode().  Pach by Bruno Cauet.

* bpo-22960: Add a context argument to xmlrpclib.ServerProxy
  constructor.

* bpo-22389: Add contextlib.redirect_stderr().

* bpo-21356: Make ssl.RAND_egd() optional to support LibreSSL. The
  availability of the function is checked during the compilation.
  Patch written by Bernard Spil.

* bpo-22915: SAX parser now supports files opened with file descriptor
  or bytes path.

* bpo-22609: Constructors and update methods of mapping classes in the
  collections module now accept the self keyword argument.

* bpo-22940: Add readline.append_history_file.

* bpo-19676: Added the “namereplace” error handler.

* bpo-22788: Add *context* parameter to logging.handlers.HTTPHandler.

* bpo-22921: Allow SSLContext to take the *hostname* parameter even if
  OpenSSL doesn’t support SNI.

* bpo-22894: TestCase.subTest() would cause the test suite to be
  stopped when in failfast mode, even in the absence of failures.

* bpo-22796: HTTP cookie parsing is now stricter, in order to protect
  against potential injection attacks.

* bpo-22370: Windows detection in pathlib is now more robust.

* bpo-22841: Reject coroutines in asyncio add_signal_handler(). Patch
  by Ludovic.Gasc.

* bpo-19494: Added urllib.request.HTTPBasicPriorAuthHandler. Patch by
  Matej Cepl.

* bpo-22578: Added attributes to the re.error class.

* bpo-22849: Fix possible double free in the io.TextIOWrapper
  constructor.

* bpo-12728: Different Unicode characters having the same uppercase
  but different lowercase are now matched in case-insensitive regular
  expressions.

* bpo-22821: Fixed fcntl() with integer argument on 64-bit big-endian
  platforms.

* bpo-21650: Add an "--sort-keys" option to json.tool CLI.

* bpo-22824: Updated reprlib output format for sets to use set
  literals. Patch contributed by Berker Peksag.

* bpo-22824: Updated reprlib output format for arrays to display empty
  arrays without an unnecessary empty list.  Suggested by Serhiy
  Storchaka.

* bpo-22406: Fixed the uu_codec codec incorrectly ported to 3.x. Based
  on patch by Martin Panter.

* bpo-17293: uuid.getnode() now determines MAC address on AIX using
  netstat. Based on patch by Aivars Kalvāns.

* bpo-22769: Fixed ttk.Treeview.tag_has() when called without
  arguments.

* bpo-22417: Verify certificates by default in httplib (PEP 476).

* bpo-22775: Fixed unpickling of http.cookies.SimpleCookie with
  protocol 2 and above. Patch by Tim Graham.

* bpo-22776: Brought excluded code into the scope of a try block in
  SysLogHandler.emit().

* bpo-22665: Add missing get_terminal_size and SameFileError to
  shutil.__all__.

* bpo-6623: Remove deprecated Netrc class in the ftplib module. Patch
  by Matt Chaput.

* bpo-17381: Fixed handling of case-insensitive ranges in regular
  expressions.

* bpo-22410: Module level functions in the re module now cache
  compiled locale-dependent regular expressions taking into account
  the locale.

* bpo-22759: Query methods on pathlib.Path() (exists(), is_dir(),
  etc.) now return False when the underlying stat call raises
  NotADirectoryError.

* bpo-8876: distutils now falls back to copying files when hard
  linking doesn’t work. This allows use with special filesystems such
  as VirtualBox shared folders.

* bpo-22217: Implemented reprs of classes in the zipfile module.

* bpo-22457: Honour load_tests in the start_dir of discovery.

* bpo-18216: gettext now raises an error when a .mo file has an
  unsupported major version number.  Patch by Aaron Hill.

* bpo-13918: Provide a locale.delocalize() function which can remove
  locale-specific number formatting from a string representing a
  number, without then converting it to a specific type.  Patch by
  Cédric Krier.

* bpo-22676: Make the pickling of global objects which don’t have a
  __module__ attribute less slow.

* bpo-18853: Fixed ResourceWarning in shlex.__nain__.

* bpo-9351: Defaults set with set_defaults on an argparse subparser
  are no longer ignored when also set on the parent parser.

* bpo-7559: unittest test loading ImportErrors are reported as import
  errors with their import exception rather than as attribute errors
  after the import has already failed.

* bpo-19746: Make it possible to examine the errors from unittest
  discovery without executing the test suite. The new "errors"
  attribute on TestLoader exposes these non-fatal errors encountered
  during discovery.

* bpo-21991: Make email.headerregistry’s header ‘params’ attributes be
  read-only (MappingProxyType).  Previously the dictionary was
  modifiable but a new one was created on each access of the
  attribute.

* bpo-22638: SSLv3 is now disabled throughout the standard library. It
  can still be enabled by instantiating a SSLContext manually.

* bpo-22641: In asyncio, the default SSL context for client
  connections is now created using ssl.create_default_context(), for
  stronger security.

* bpo-17401: Include closefd in io.FileIO repr.

* bpo-21338: Add silent mode for compileall. quiet parameters of
  compile_{dir, file, path} functions now have a multilevel value.
  Also, -q option of the CLI now have a multilevel value. Patch by
  Thomas Kluyver.

* bpo-20152: Convert the array and cmath modules to Argument Clinic.

* bpo-18643: Add socket.socketpair() on Windows.

* bpo-22435: Fix a file descriptor leak when socketserver bind fails.

* bpo-13096: Fixed segfault in CTypes POINTER handling of large
  values.

* bpo-11694: Raise ConversionError in xdrlib as documented.  Patch by
  Filip Gruszczyński and Claudiu Popa.

* bpo-19380: Optimized parsing of regular expressions.

* bpo-1519638: Now unmatched groups are replaced with empty strings in
  re.sub() and re.subn().

* bpo-18615: sndhdr.what/whathdr now return a namedtuple.

* bpo-22462: Fix pyexpat’s creation of a dummy frame to make it appear
  in exception tracebacks.

* bpo-21965: Add support for in-memory SSL to the ssl module.  Patch
  by Geert Jansen.

* bpo-21173: Fix len() on a WeakKeyDictionary when .clear() was called
  with an iterator alive.

* bpo-11866: Eliminated race condition in the computation of names for
  new threads.

* bpo-21905: Avoid RuntimeError in pickle.whichmodule() when
  sys.modules is mutated while iterating.  Patch by Olivier Grisel.

* bpo-11271: concurrent.futures.Executor.map() now takes a *chunksize*
  argument to allow batching of tasks in child processes and improve
  performance of ProcessPoolExecutor.  Patch by Dan O’Reilly.

* bpo-21883: os.path.join() and os.path.relpath() now raise a
  TypeError with more helpful error message for unsupported or
  mismatched types of arguments.

* bpo-22219: The zipfile module CLI now adds entries for directories
  (including empty directories) in ZIP file.

* bpo-22449: In the ssl.SSLContext.load_default_certs, consult the
  environmental variables SSL_CERT_DIR and SSL_CERT_FILE on Windows.

* bpo-22508: The email.__version__ variable has been removed; the
  email code is no longer shipped separately from the stdlib, and
  __version__ hasn’t been updated in several releases.

* bpo-20076: Added non derived UTF-8 aliases to locale aliases table.

* bpo-20079: Added locales supported in glibc 2.18 to locale alias
  table.

* bpo-20218: Added convenience methods read_text/write_text and
  read_bytes/ write_bytes to pathlib.Path objects.

* bpo-22396: On 32-bit AIX platform, don’t expose os.posix_fadvise()
  nor os.posix_fallocate() because their prototypes in system headers
  are wrong.

* bpo-22517: When an io.BufferedRWPair object is deallocated, clear
  its weakrefs.

* bpo-22437: Number of capturing groups in regular expression is no
  longer limited by 100.

* bpo-17442: InteractiveInterpreter now displays the full chained
  traceback in its showtraceback method, to match the built in
  interactive interpreter.

* bpo-23392: Added tests for marshal C API that works with FILE*.

* bpo-10510: distutils register and upload methods now use HTML
  standards compliant CRLF line endings.

* bpo-9850: Fixed macpath.join() for empty first component.  Patch by
  Oleg Oshmyan.

* bpo-5309: distutils’ build and build_ext commands now accept a "-j"
  option to enable parallel building of extension modules.

* bpo-22448: Improve canceled timer handles cleanup to prevent unbound
  memory usage. Patch by Joshua Moore-Oliva.

* bpo-22427: TemporaryDirectory no longer attempts to clean up twice
  when used in the with statement in generator.

* bpo-22362: Forbidden ambiguous octal escapes out of range 0-0o377 in
  regular expressions.

* bpo-20912: Now directories added to ZIP file have correct Unix and
  MS-DOS directory attributes.

* bpo-21866: ZipFile.close() no longer writes ZIP64 central directory
  records if allowZip64 is false.

* bpo-22278: Fix urljoin problem with relative urls, a regression
  observed after changes to issue22118 were submitted.

* bpo-22415: Fixed debugging output of the GROUPREF_EXISTS opcode in
  the re module. Removed trailing spaces in debugging output.

* bpo-22423: Unhandled exception in thread no longer causes unhandled
  AttributeError when sys.stderr is None.

* bpo-21332: Ensure that "bufsize=1" in subprocess.Popen() selects
  line buffering, rather than block buffering.  Patch by Akira Li.

* bpo-21091: Fix API bug: email.message.EmailMessage.is_attachment is
  now a method.

* bpo-21079: Fix email.message.EmailMessage.is_attachment to return
  the correct result when the header has parameters as well as a
  value.

* bpo-22247: Add NNTPError to nntplib.__all__.

* bpo-22366: urllib.request.urlopen will accept a context object
  (SSLContext) as an argument which will then be used for HTTPS
  connection. Patch by Alex Gaynor.

* bpo-4180: The warnings registries are now reset when the filters are
  modified.

* bpo-22419: Limit the length of incoming HTTP request in wsgiref
  server to 65536 bytes and send a 414 error code for higher lengths.
  Patch contributed by Devin Cook.

* Lax cookie parsing in http.cookies could be a security issue when
  combined with non-standard cookie handling in some web browsers.
  Reported by Sergey Bobrov.

* bpo-20537: logging methods now accept an exception instance as well
  as a Boolean value or exception tuple. Thanks to Yury Selivanov for
  the patch.

* bpo-22384: An exception in Tkinter callback no longer crashes the
  program when it is run with pythonw.exe.

* bpo-22168: Prevent turtle AttributeError with non-default Canvas on
  OS X.

* bpo-21147: sqlite3 now raises an exception if the request contains a
  null character instead of truncating it.  Based on patch by Victor
  Stinner.

* bpo-13968: The glob module now supports recursive search in
  subdirectories using the "**" pattern.

* bpo-21951: Fixed a crash in Tkinter on AIX when called Tcl command
  with empty string or tuple argument.

* bpo-21951: Tkinter now most likely raises MemoryError instead of
  crash if the memory allocation fails.

* bpo-22338: Fix a crash in the json module on memory allocation
  failure.

* bpo-12410: imaplib.IMAP4 now supports the context management
  protocol. Original patch by Tarek Ziadé.

* bpo-21270: We now override tuple methods in mock.call objects so
  that they can be used as normal call attributes.

* bpo-16662: load_tests() is now unconditionally run when it is
  present in a package’s __init__.py.
  TestLoader.loadTestsFromModule() still accepts use_load_tests, but
  it is deprecated and ignored.  A new keyword-only attribute
  "pattern" is added and documented.  Patch given by Robert Collins,
  tweaked by Barry Warsaw.

* bpo-22226: First letter no longer is stripped from the “status” key
  in the result of Treeview.heading().

* bpo-19524: Fixed resource leak in the HTTP connection when an
  invalid response is received.  Patch by Martin Panter.

* bpo-20421: Add a .version() method to SSL sockets exposing the
  actual protocol version in use.

* bpo-19546: configparser exceptions no longer expose implementation
  details. Chained KeyErrors are removed, which leads to cleaner
  tracebacks. Patch by Claudiu Popa.

* bpo-22051: turtledemo no longer reloads examples to re-run them.
  Initialization of variables and gui setup should be done in main(),
  which is called each time a demo is run, but not on import.

* bpo-21933: Turtledemo users can change the code font size with a
  menu selection or control(command) ‘-’ or ‘+’ or control-mousewheel.
  Original patch by Lita Cho.

* bpo-21597: The separator between the turtledemo text pane and the
  drawing canvas can now be grabbed and dragged with a mouse.  The
  code text pane can be widened to easily view or copy the full width
  of the text.  The canvas can be widened on small screens.  Original
  patches by Jan Kanis and Lita Cho.

* bpo-18132: Turtledemo buttons no longer disappear when the window is
  shrunk.  Original patches by Jan Kanis and Lita Cho.

* bpo-22043: time.monotonic() is now always available.
  "threading.Lock.acquire()", "threading.RLock.acquire()" and socket
  operations now use a monotonic clock, instead of the system clock,
  when a timeout is used.

* bpo-21527: Add a default number of workers to ThreadPoolExecutor
  equal to 5 times the number of CPUs.  Patch by Claudiu Popa.

* bpo-22216: smtplib now resets its state more completely after a
  quit.  The most obvious consequence of the previous behavior was a
  STARTTLS failure during a connect/starttls/quit/connect/starttls
  sequence.

* bpo-22098: ctypes’ BigEndianStructure and LittleEndianStructure now
  define an empty __slots__ so that subclasses don’t always get an
  instance dict. Patch by Claudiu Popa.

* bpo-22185: Fix an occasional RuntimeError in
  threading.Condition.wait() caused by mutation of the waiters queue
  without holding the lock.  Patch by Doug Zongker.

* bpo-22287: On UNIX, _PyTime_gettimeofday() now uses
  clock_gettime(CLOCK_REALTIME) if available. As a side effect, Python
  now depends on the librt library on Solaris and on Linux (only with
  glibc older than 2.17).

* bpo-22182: Use e.args to unpack exceptions correctly in
  distutils.file_util.move_file. Patch by Claudiu Popa.

* The webbrowser module now uses subprocess’s start_new_session=True
  rather than a potentially risky preexec_fn=os.setsid call.

* bpo-22042: signal.set_wakeup_fd(fd) now raises an exception if the
  file descriptor is in blocking mode.

* bpo-16808: inspect.stack() now returns a named tuple instead of a
  tuple. Patch by Daniel Shahaf.

* bpo-22236: Fixed Tkinter images copying operations in NoDefaultRoot
  mode.

* bpo-2527: Add a *globals* argument to timeit functions, in order to
  override the globals namespace in which the timed code is executed.
  Patch by Ben Roberts.

* bpo-22118: Switch urllib.parse to use RFC 3986 semantics for the
  resolution of relative URLs, rather than RFCs 1808 and 2396. Patch
  by Demian Brecht.

* bpo-21549: Added the “members” parameter to TarFile.list().

* bpo-19628: Allow compileall recursion depth to be specified with a
  -r option.

* bpo-15696: Add a __sizeof__ implementation for mmap objects on
  Windows.

* bpo-22068: Avoided reference loops with Variables and Fonts in
  Tkinter.

* bpo-22165: SimpleHTTPRequestHandler now supports undecodable file
  names.

* bpo-15381: Optimized line reading in io.BytesIO.

* bpo-8797: Raise HTTPError on failed Basic Authentication
  immediately. Initial patch by Sam Bull.

* bpo-20729: Restored the use of lazy
  iterkeys()/itervalues()/iteritems() in the mailbox module.

* bpo-21448: Changed FeedParser feed() to avoid O(N^2) behavior when
  parsing long line. Original patch by Raymond Hettinger.

* bpo-22184: The functools LRU Cache decorator factory now gives an
  earlier and clearer error message when the user forgets the required
  parameters.

* bpo-17923: glob() patterns ending with a slash no longer match non-
  dirs on AIX.  Based on patch by Delhallt.

* bpo-21725: Added support for RFC 6531 (SMTPUTF8) in smtpd.

* bpo-22176: Update the ctypes module’s libffi to v3.1.  This release
  adds support for the Linux AArch64 and POWERPC ELF ABIv2 little
  endian architectures.

* bpo-5411: Added support for the “xztar” format in the shutil module.

* bpo-21121: Don’t force 3rd party C extensions to be built with
  -Werror=declaration-after-statement.

* bpo-21975: Fixed crash when using uninitialized sqlite3.Row (in
  particular when unpickling pickled sqlite3.Row).  sqlite3.Row is now
  initialized in the __new__() method.

* bpo-20170: Convert posixmodule to use Argument Clinic.

* bpo-21539: Add an *exists_ok* argument to "Pathlib.mkdir()" to mimic
  "mkdir -p" and "os.makedirs()" functionality.  When true, ignore
  FileExistsErrors.  Patch by Berker Peksag.

* bpo-22127: Bypass IDNA for pure-ASCII host names in the socket
  module (in particular for numeric IPs).

* bpo-21047: set the default value for the *convert_charrefs* argument
  of HTMLParser to True.  Patch by Berker Peksag.

* Add an __all__ to html.entities.

* bpo-15114: the strict mode and argument of HTMLParser,
  HTMLParser.error, and the HTMLParserError exception have been
  removed.

* bpo-22085: Dropped support of Tk 8.3 in Tkinter.

* bpo-21580: Now Tkinter correctly handles bytes arguments passed to
  Tk. In particular this allows initializing images from binary data.

* bpo-22003: When initialized from a bytes object, io.BytesIO() now
  defers making a copy until it is mutated, improving performance and
  memory use on some use cases. Patch by David Wilson.

* bpo-22018: On Windows, signal.set_wakeup_fd() now also supports
  sockets. A side effect is that Python depends to the WinSock
  library.

* bpo-22054: Add os.get_blocking() and os.set_blocking() functions to
  get and set the blocking mode of a file descriptor (False if the
  O_NONBLOCK flag is set, True otherwise). These functions are not
  available on Windows.

* bpo-17172: Make turtledemo start as active on OS X even when run
  with subprocess. Patch by Lita Cho.

* bpo-21704: Fix build error for _multiprocessing when semaphores are
  not available. Patch by Arfrever Frehtes Taifersar Arahesis.

* bpo-20173: Convert sha1, sha256, sha512 and md5 to ArgumentClinic.
  Patch by Vajrasky Kok.

* Fix repr(_socket.socket) on Windows 64-bit: don’t fail with
  OverflowError on closed socket. repr(socket.socket) already works
  fine.

* bpo-22033: Reprs of most Python implemented classes now contain
  actual class name instead of hardcoded one.

* bpo-21947: The dis module can now disassemble generator-iterator
  objects based on their gi_code attribute. Patch by Clement Rouault.

* bpo-16133: The asynchat.async_chat.handle_read() method now ignores
  BlockingIOError exceptions.

* bpo-22044: Fixed premature DECREF in call_tzinfo_method. Patch by
  Tom Flanagan.

* bpo-19884: readline: Disable the meta modifier key if stdout is not
  a terminal to not write the ANSI sequence ""\033[1034h"" into
  stdout. This sequence is used on some terminal (ex: TERM=xterm-
  256color”) to enable support of 8 bit characters.

* bpo-4350: Removed a number of out-of-dated and non-working for a
  long time Tkinter methods.

* bpo-6167: Scrollbar.activate() now returns the name of active
  element if the argument is not specified.  Scrollbar.set() now
  always accepts only 2 arguments.

* bpo-15275: Clean up and speed up the ntpath module.

* bpo-21888: plistlib’s load() and loads() now work if the fmt
  parameter is specified.

* bpo-22032: __qualname__ instead of __name__ is now always used to
  format fully qualified class names of Python implemented classes.

* bpo-22031: Reprs now always use hexadecimal format with the “0x”
  prefix when contain an id in form ” at 0x…”.

* bpo-22018: signal.set_wakeup_fd() now raises an OSError instead of a
  ValueError on "fstat()" failure.

* bpo-21044: tarfile.open() now handles fileobj with an integer ‘name’
  attribute.  Based on patch by Antoine Pietri.

* bpo-21966: Respect -q command-line option when code module is ran.

* bpo-19076: Don’t pass the redundant ‘file’ argument to self.error().

* bpo-16382: Improve exception message of warnings.warn() for bad
  category. Initial patch by Phil Elson.

* bpo-21932: os.read() now uses a "Py_ssize_t()" type instead of "int"
  for the size to support reading more than 2 GB at once. On Windows,
  the size is truncated to INT_MAX. As any call to os.read(), the OS
  may read less bytes than the number of requested bytes.

* bpo-21942: Fixed source file viewing in pydoc’s server mode on
  Windows.

* bpo-11259: asynchat.async_chat().set_terminator() now raises a
  ValueError if the number of received bytes is negative.

* bpo-12523: asynchat.async_chat.push() now raises a TypeError if it
  doesn’t get a bytes string

* bpo-21707: Add missing kwonlyargcount argument to
  ModuleFinder.replace_paths_in_code().

* bpo-20639: calling Path.with_suffix(‘’) allows removing the suffix
  again. Patch by July Tikhonov.

* bpo-21714: Disallow the construction of invalid paths using
  Path.with_name().  Original patch by Antony Lee.

* bpo-15014: Added ‘auth’ method to smtplib to make implementing auth
  mechanisms simpler, and used it internally in the login method.

* bpo-21151: Fixed a segfault in the winreg module when "None" is
  passed as a "REG_BINARY" value to SetValueEx.  Patch by John
  Ehresman.

* bpo-21090: io.FileIO.readall() does not ignore I/O errors anymore.
  Before, it ignored I/O errors if at least the first C call read()
  succeed.

* bpo-5800: headers parameter of wsgiref.headers.Headers is now
  optional. Initial patch by Pablo Torres Navarrete and SilentGhost.

* bpo-21781: ssl.RAND_add() now supports strings longer than 2 GB.

* bpo-21679: Prevent extraneous fstat() calls during open().  Patch by
  Bohuslav Kabrda.

* bpo-21863: cProfile now displays the module name of C extension
  functions, in addition to their own name.

* bpo-11453: asyncore: emit a ResourceWarning when an unclosed
  file_wrapper object is destroyed. The destructor now closes the file
  if needed. The close() method can now be called twice: the second
  call does nothing.

* bpo-21858: Better handling of Python exceptions in the sqlite3
  module.

* bpo-21476: Make sure the email.parser.BytesParser TextIOWrapper is
  discarded after parsing, so the input file isn’t unexpectedly
  closed.

* bpo-20295: imghdr now recognizes OpenEXR format images.

* bpo-21729: Used the “with” statement in the dbm.dumb module to
  ensure files closing. Patch by Claudiu Popa.

* bpo-21491: socketserver: Fix a race condition in child processes
  reaping.

* bpo-21719: Added the "st_file_attributes" field to os.stat_result on
  Windows.

* bpo-21832: Require named tuple inputs to be exact strings.

* bpo-21722: The distutils “upload” command now exits with a non-zero
  return code when uploading fails.  Patch by Martin Dengler.

* bpo-21723: asyncio.Queue: support any type of number (ex: float) for
  the maximum size. Patch written by Vajrasky Kok.

* bpo-21711: support for “site-python” directories has now been
  removed from the site module (it was deprecated in 3.4).

* bpo-17552: new socket.sendfile() method allowing a file to be sent
  over a socket by using high-performance os.sendfile() on UNIX. Patch
  by Giampaolo Rodola’.

* bpo-18039: dbm.dump.open() now always creates a new database when
  the flag has the value ‘n’.  Patch by Claudiu Popa.

* bpo-21326: Add a new is_closed() method to asyncio.BaseEventLoop.
  run_forever() and run_until_complete() methods of
  asyncio.BaseEventLoop now raise an exception if the event loop was
  closed.

* bpo-21766: Prevent a security hole in CGIHTTPServer by URL unquoting
  paths before checking for a CGI script at that path.

* bpo-21310: Fixed possible resource leak in failed open().

* bpo-21256: Printout of keyword args should be in deterministic order
  in a mock function call. This will help to write better doctests.

* bpo-21677: Fixed chaining nonnormalized exceptions in io close()
  methods.

* bpo-11709: Fix the pydoc.help function to not fail when sys.stdin is
  not a valid file.

* bpo-21515: tempfile.TemporaryFile now uses os.O_TMPFILE flag is
  available.

* bpo-13223: Fix pydoc.writedoc so that the HTML documentation for
  methods that use ‘self’ in the example code is generated correctly.

* bpo-21463: In urllib.request, fix pruning of the FTP cache.

* bpo-21618: The subprocess module could fail to close open fds that
  were inherited by the calling process and already higher than POSIX
  resource limits would otherwise allow.  On systems with a
  functioning /proc/self/fd or /dev/fd interface the max is now
  ignored and all fds are closed.

* bpo-20383: Introduce importlib.util.module_from_spec() as the
  preferred way to create a new module.

* bpo-21552: Fixed possible integer overflow of too long string
  lengths in the tkinter module on 64-bit platforms.

* bpo-14315: The zipfile module now ignores extra fields in the
  central directory that are too short to be parsed instead of letting
  a struct.unpack error bubble up as this “bad data” appears in many
  real world zip files in the wild and is ignored by other zip tools.

* bpo-13742: Added “key” and “reverse” parameters to heapq.merge().
  (First draft of patch contributed by Simon Sapin.)

* bpo-21402: tkinter.ttk now works when default root window is not
  set.

* bpo-3015: _tkinter.create() now creates tkapp object with
  wantobject=1 by default.

* bpo-10203: sqlite3.Row now truly supports sequence protocol.  In
  particular it supports reverse() and negative indices.  Original
  patch by Claudiu Popa.

* bpo-18807: If copying (no symlinks) specified for a venv, then the
  python interpreter aliases (python, python3) are now created by
  copying rather than symlinking.

* bpo-20197: Added support for the WebP image type in the imghdr
  module. Patch by Fabrice Aneche and Claudiu Popa.

* bpo-21513: Speedup some properties of IP addresses (IPv4Address,
  IPv6Address) such as .is_private or .is_multicast.

* bpo-21137: Improve the repr for threading.Lock() and its variants by
  showing the “locked” or “unlocked” status.  Patch by Berker Peksag.

* bpo-21538: The plistlib module now supports loading of binary plist
  files when reference or offset size is not a power of two.

* bpo-21455: Add a default backlog to socket.listen().

* bpo-21525: Most Tkinter methods which accepted tuples now accept
  lists too.

* bpo-22166: With the assistance of a new internal
  _codecs._forget_codec helping function, test_codecs now clears the
  encoding caches to avoid the appearance of a reference leak

* bpo-22236: Tkinter tests now don’t reuse default root window.  New
  root window is created for every test class.

* bpo-10744: Fix **PEP 3118** format strings on ctypes objects with a
  nontrivial shape.

* bpo-20826: Optimize ipaddress.collapse_addresses().

* bpo-21487: Optimize ipaddress.summarize_address_range() and
  ipaddress.{IPv4Network,IPv6Network}.subnets().

* bpo-21486: Optimize parsing of netmasks in ipaddress.IPv4Network and
  ipaddress.IPv6Network.

* bpo-13916: Disallowed the surrogatepass error handler for non UTF-*
  encodings.

* bpo-20998: Fixed re.fullmatch() of repeated single character pattern
  with ignore case. Original patch by Matthew Barnett.

* bpo-21075: fileinput.FileInput now reads bytes from standard stream
  if binary mode is specified.  Patch by Sam Kimbrel.

* bpo-19775: Add a samefile() method to pathlib Path objects.  Initial
  patch by Vajrasky Kok.

* bpo-21226: Set up modules properly in PyImport_ExecCodeModuleObject
  (and friends).

* bpo-21398: Fix a unicode error in the pydoc pager when the
  documentation contains characters not encodable to the stdout
  encoding.

* bpo-16531: ipaddress.IPv4Network and ipaddress.IPv6Network now
  accept an (address, netmask) tuple argument, so as to easily
  construct network objects from existing addresses.

* bpo-21156: importlib.abc.InspectLoader.source_to_code() is now a
  staticmethod.

* bpo-21424: Simplified and optimized heaqp.nlargest() and
  nmsmallest() to make fewer tuple comparisons.

* bpo-21396: Fix TextIOWrapper(…, write_through=True) to not force a
  flush() on the underlying binary stream.  Patch by akira.

* bpo-18314: Unlink now removes junctions on Windows. Patch by Kim
  Gräsman

* bpo-21088: Bugfix for curses.window.addch() regression in 3.4.0. In
  porting to Argument Clinic, the first two arguments were reversed.

* bpo-21407: _decimal: The module now supports function signatures.

* bpo-10650: Remove the non-standard ‘watchexp’ parameter from the
  Decimal.quantize() method in the Python version.  It had never been
  present in the C version.

* bpo-21469: Reduced the risk of false positives in robotparser by
  checking to make sure that robots.txt has been read or does not
  exist prior to returning True in can_fetch().

* bpo-19414: Have the OrderedDict mark deleted links as unusable. This
  gives an early failure if the link is deleted during iteration.

* bpo-21421: Add __slots__ to the MappingViews ABC. Patch by Josh
  Rosenberg.

* bpo-21101: Eliminate double hashing in the C speed-up code for
  collections.Counter().

* bpo-21321: itertools.islice() now releases the reference to the
  source iterator when the slice is exhausted.  Patch by Anton
  Afanasyev.

* bpo-21057: TextIOWrapper now allows the underlying binary stream’s
  read() or read1() method to return an arbitrary bytes-like object
  (such as a memoryview). Patch by Nikolaus Rath.

* bpo-20951: SSLSocket.send() now raises either SSLWantReadError or
  SSLWantWriteError on a non-blocking socket if the operation would
  block. Previously, it would return 0.  Patch by Nikolaus Rath.

* bpo-13248: removed previously deprecated asyncore.dispatcher
  __getattr__ cheap inheritance hack.

* bpo-9815: assertRaises now tries to clear references to local
  variables in the exception’s traceback.

* bpo-19940: ssl.cert_time_to_seconds() now interprets the given time
  string in the UTC timezone (as specified in RFC 5280), not the local
  timezone.

* bpo-13204: Calling sys.flags.__new__ would crash the interpreter,
  now it raises a TypeError.

* bpo-19385: Make operations on a closed dbm.dumb database always
  raise the same exception.

* bpo-21207: Detect when the os.urandom cached fd has been closed or
  replaced, and open it anew.

* bpo-21291: subprocess’s Popen.wait() is now thread safe so that
  multiple threads may be calling wait() or poll() on a Popen instance
  at the same time without losing the Popen.returncode value.

* bpo-21127: Path objects can now be instantiated from str subclass
  instances (such as "numpy.str_").

* bpo-15002: urllib.response object to use _TemporaryFileWrapper (and
  _TemporaryFileCloser) facility. Provides a better way to handle file
  descriptor close. Patch contributed by Christian Theune.

* bpo-12220: mindom now raises a custom ValueError indicating it
  doesn’t support spaces in URIs instead of letting a ‘split’
  ValueError bubble up.

* bpo-21068: The ssl.PROTOCOL* constants are now enum members.

* bpo-21276: posixmodule: Don’t define USE_XATTRS on KFreeBSD and the
  Hurd.

* bpo-21262: New method assert_not_called for Mock. It raises
  AssertionError if the mock has been called.

* bpo-21238: New keyword argument "unsafe" to Mock. It raises
  "AttributeError" incase of an attribute startswith assert or assret.

* bpo-20896: ssl.get_server_certificate() now uses PROTOCOL_SSLv23,
  not PROTOCOL_SSLv3, for maximum compatibility.

* bpo-21239: patch.stopall() didn’t work deterministically when the
  same name was patched more than once.

* bpo-21203: Updated fileConfig and dictConfig to remove
  inconsistencies. Thanks to Jure Koren for the patch.

* bpo-21222: Passing name keyword argument to mock.create_autospec now
  works.

* bpo-21197: Add lib64 -> lib symlink in venvs on 64-bit non-OS X
  POSIX.

* bpo-17498: Some SMTP servers disconnect after certain errors,
  violating strict RFC conformance.  Instead of losing the error code
  when we issue the subsequent RSET, smtplib now returns the error
  code and defers raising the SMTPServerDisconnected error until the
  next command is issued.

* bpo-17826: setting an iterable side_effect on a mock function
  created by create_autospec now works. Patch by Kushal Das.

* bpo-7776: Fix "Host:" header and reconnection when using
  http.client.HTTPConnection.set_tunnel(). Patch by Nikolaus Rath.

* bpo-20968: unittest.mock.MagicMock now supports division. Patch by
  Johannes Baiter.

* bpo-21529: Fix arbitrary memory access in JSONDecoder.raw_decode
  with a negative second parameter. Bug reported by Guido Vranken.
  (See also: CVE-2014-4616)

* bpo-21169: getpass now handles non-ascii characters that the input
  stream encoding cannot encode by re-encoding using the replace error
  handler.

* bpo-21171: Fixed undocumented filter API of the rot13 codec. Patch
  by Berker Peksag.

* bpo-20539: Improved math.factorial error message for large positive
  inputs and changed exception type (OverflowError -> ValueError) for
  large negative inputs.

* bpo-21172: isinstance check relaxed from dict to
  collections.Mapping.

* bpo-21155: asyncio.EventLoop.create_unix_server() now raises a
  ValueError if path and sock are specified at the same time.

* bpo-21136: Avoid unnecessary normalization of Fractions resulting
  from power and other operations.  Patch by Raymond Hettinger.

* bpo-17621: Introduce importlib.util.LazyLoader.

* bpo-21076: signal module constants were turned into enums. Patch by
  Giampaolo Rodola’.

* bpo-20636: Improved the repr of Tkinter widgets.

* bpo-19505: The items, keys, and values views of OrderedDict now
  support reverse iteration using reversed().

* bpo-21149: Improved thread-safety in logging cleanup during
  interpreter shutdown. Thanks to Devin Jeanpierre for the patch.

* bpo-21058: Fix a leak of file descriptor in
  "tempfile.NamedTemporaryFile()", close the file descriptor if
  "io.open()" fails

* bpo-21200: Return None from pkgutil.get_loader() when __spec__ is
  missing.

* bpo-21013: Enhance ssl.create_default_context() when used for server
  side sockets to provide better security by default.

* bpo-20145: "assertRaisesRegex" and "assertWarnsRegex" now raise a
  TypeError if the second argument is not a string or compiled regex.

* bpo-20633: Replace relative import by absolute import.

* bpo-20980: Stop wrapping exception when using ThreadPool.

* bpo-21082: In os.makedirs, do not set the process-wide umask. Note
  this changes behavior of makedirs when exist_ok=True.

* bpo-20990: Fix issues found by pyflakes for multiprocessing.

* bpo-21015: SSL contexts will now automatically select an elliptic
  curve for ECDH key exchange on OpenSSL 1.0.2 and later, and
  otherwise default to “prime256v1”.

* bpo-21000: Improve the command-line interface of json.tool.

* bpo-20995: Enhance default ciphers used by the ssl module to enable
  better security and prioritize perfect forward secrecy.

* bpo-20884: Don’t assume that __file__ is defined on
  importlib.__init__.

* bpo-21499: Ignore __builtins__ in several test_importlib.test_api
  tests.

* bpo-20627: xmlrpc.client.ServerProxy is now a context manager.

* bpo-19165: The formatter module now raises DeprecationWarning
  instead of PendingDeprecationWarning.

* bpo-13936: Remove the ability of datetime.time instances to be
  considered false in boolean contexts.

* bpo-18931: selectors module now supports /dev/poll on Solaris. Patch
  by Giampaolo Rodola’.

* bpo-19977: When the "LC_TYPE" locale is the POSIX locale ("C"
  locale), "sys.stdin" and "sys.stdout" are now using the
  "surrogateescape" error handler, instead of the "strict" error
  handler.

* bpo-20574: Implement incremental decoder for cp65001 code (Windows
  code page 65001, Microsoft UTF-8).

* bpo-20879: Delay the initialization of encoding and decoding tables
  for base32, ascii85 and base85 codecs in the base64 module, and
  delay the initialization of the unquote_to_bytes() table of the
  urllib.parse module, to not waste memory if these modules are not
  used.

* bpo-19157: Include the broadcast address in the usuable hosts for
  IPv6 in ipaddress.

* bpo-11599: When an external command (e.g. compiler) fails, distutils
  now prints out the whole command line (instead of just the command
  name) if the environment variable DISTUTILS_DEBUG is set.

* bpo-4931: distutils should not produce unhelpful “error: None”
  messages anymore. distutils.util.grok_environment_error is kept but
  doc-deprecated.

* bpo-20875: Prevent possible gzip “‘read’ is not defined” NameError.
  Patch by Claudiu Popa.

* bpo-11558: "email.message.Message.attach" now returns a more useful
  error message if "attach" is called on a message for which
  "is_multipart" is False.

* bpo-20283: RE pattern methods now accept the string keyword
  parameters as documented. The pattern and source keyword parameters
  are left as deprecated aliases.

* bpo-20778: Fix modulefinder to work with bytecode-only modules.

* bpo-20791: copy.copy() now doesn’t make a copy when the input is a
  bytes object. Initial patch by Peter Otten.

* bpo-19748: On AIX, time.mktime() now raises an OverflowError for
  year outsize range [1902; 2037].

* bpo-19573: inspect.signature: Use enum for parameter kind constants.

* bpo-20726: inspect.signature: Make Signature and Parameter
  picklable.

* bpo-17373: Add inspect.Signature.from_callable method.

* bpo-20378: Improve repr of inspect.Signature and inspect.Parameter.

* bpo-20816: Fix inspect.getcallargs() to raise correct TypeError for
  missing keyword-only arguments. Patch by Jeremiah Lowin.

* bpo-20817: Fix inspect.getcallargs() to fail correctly if more than
  3 arguments are missing. Patch by Jeremiah Lowin.

* bpo-6676: Ensure a meaningful exception is raised when attempting to
  parse more than one XML document per pyexpat xmlparser instance.
  (Original patches by Hirokazu Yamamoto and Amaury Forgeot d’Arc,
  with suggested wording by David Gutteridge)

* bpo-21117: Fix inspect.signature to better support
  functools.partial. Due to the specifics of functools.partial
  implementation, positional-or-keyword arguments passed as keyword
  arguments become keyword-only.

* bpo-20334: inspect.Signature and inspect.Parameter are now hashable.
  Thanks to Antony Lee for bug reports and suggestions.

* bpo-15916: doctest.DocTestSuite returns an empty unittest.TestSuite
  instead of raising ValueError if it finds no tests

* bpo-21209: Fix asyncio.tasks.CoroWrapper to workaround a bug in
  yield-from implementation in CPythons prior to 3.4.1.

* asyncio: Add gi_{frame,running,code} properties to CoroWrapper
  (upstream bpo-163).

* bpo-21311: Avoid exception in _osx_support with non-standard
  compiler configurations. Patch by John Szakmeister.

* bpo-11571: Ensure that the turtle window becomes the topmost window
  when launched on OS X.

* bpo-21801: Validate that __signature__ is None or an instance of
  Signature.

* bpo-21923: Prevent AttributeError in
  distutils.sysconfig.customize_compiler due to possible uninitialized
  _config_vars.

* bpo-21323: Fix http.server to again handle scripts in CGI
  subdirectories, broken by the fix for security bpo-19435.  Patch by
  Zach Byrne.

* bpo-22733: Fix ffi_prep_args not zero-extending argument values
  correctly on 64-bit Windows.

* bpo-23302: Default to TCP_NODELAY=1 upon establishing an
  HTTPConnection. Removed use of hard-coded MSS as it’s an
  optimization that’s no longer needed with Nagle disabled.


IDLE
----

* bpo-20577: Configuration of the max line length for the
  FormatParagraph extension has been moved from the General tab of the
  Idle preferences dialog to the FormatParagraph tab of the Config
  Extensions dialog. Patch by Tal Einat.

* bpo-16893: Update Idle doc chapter to match current Idle and add new
  information.

* bpo-3068: Add Idle extension configuration dialog to Options menu.
  Changes are written to HOME/.idlerc/config-extensions.cfg. Original
  patch by Tal Einat.

* bpo-16233: A module browser (File : Class Browser, Alt+C) requires
  an editor window with a filename.  When Class Browser is requested
  otherwise, from a shell, output window, or ‘Untitled’ editor, Idle
  no longer displays an error box. It now pops up an Open Module box
  (Alt+M). If a valid name is entered and a module is opened, a
  corresponding browser is also opened.

* bpo-4832: Save As to type Python files automatically adds .py to the
  name you enter (even if your system does not display it).  Some
  systems automatically add .txt when type is Text files.

* bpo-21986: Code objects are not normally pickled by the pickle
  module. To match this, they are no longer pickled when running under
  Idle.

* bpo-17390: Adjust Editor window title; remove ‘Python’, move version
  to end.

* bpo-14105: Idle debugger breakpoints no longer disappear when
  inserting or deleting lines.

* bpo-17172: Turtledemo can now be run from Idle. Currently, the entry
  is on the Help menu, but it may move to Run. Patch by Ramchandra Apt
  and Lita Cho.

* bpo-21765: Add support for non-ascii identifiers to HyperParser.

* bpo-21940: Add unittest for WidgetRedirector. Initial patch by
  Saimadhav Heblikar.

* bpo-18592: Add unittest for SearchDialogBase. Patch by Phil Webster.

* bpo-21694: Add unittest for ParenMatch. Patch by Saimadhav Heblikar.

* bpo-21686: add unittest for HyperParser. Original patch by Saimadhav
  Heblikar.

* bpo-12387: Add missing upper(lower)case versions of default Windows
  key bindings for Idle so Caps Lock does not disable them. Patch by
  Roger Serwy.

* bpo-21695: Closing a Find-in-files output window while the search is
  still in progress no longer closes Idle.

* bpo-18910: Add unittest for textView. Patch by Phil Webster.

* bpo-18292: Add unittest for AutoExpand. Patch by Saihadhav Heblikar.

* bpo-18409: Add unittest for AutoComplete. Patch by Phil Webster.

* bpo-21477: htest.py - Improve framework, complete set of tests.
  Patches by Saimadhav Heblikar

* bpo-18104: Add idlelib/idle_test/htest.py with a few sample tests to
  begin consolidating and improving human-validated tests of Idle.
  Change other files as needed to work with htest.  Running the module
  as __main__ runs all tests.

* bpo-21139: Change default paragraph width to 72, the **PEP 8**
  recommendation.

* bpo-21284: Paragraph reformat test passes after user changes
  reformat width.

* bpo-17654: Ensure IDLE menus are customized properly on OS X for
  non-framework builds and for all variants of Tk.

* bpo-23180: Rename IDLE “Windows” menu item to “Window”. Patch by Al
  Sweigart.


Build
-----

* bpo-15506: Use standard PKG_PROG_PKG_CONFIG autoconf macro in the
  configure script.

* bpo-22935: Allow the ssl module to be compiled if openssl doesn’t
  support SSL 3.

* bpo-22592: Drop support of the Borland C compiler to build Python.
  The distutils module still supports it to build extensions.

* bpo-22591: Drop support of MS-DOS, especially of the DJGPP compiler
  (MS-DOS port of GCC).

* bpo-16537: Check whether self.extensions is empty in setup.py. Patch
  by Jonathan Hosmer.

* bpo-22359: Remove incorrect uses of recursive make.  Patch by Jonas
  Wagner.

* bpo-21958: Define HAVE_ROUND when building with Visual Studio 2013
  and above.  Patch by Zachary Turner.

* bpo-18093: the programs that embed the CPython runtime are now in a
  separate “Programs” directory, rather than being kept in the Modules
  directory.

* bpo-15759: “make suspicious”, “make linkcheck” and “make doctest” in
  Doc/ now display special message when and only when there are
  failures.

* bpo-21141: The Windows build process no longer attempts to find
  Perl, instead relying on OpenSSL source being configured and ready
  to build. The "PCbuild\build_ssl.py" script has been re-written and
  re-named to "PCbuild\prepare_ssl.py", and takes care of configuring
  OpenSSL source for both 32 and 64 bit platforms.  OpenSSL sources
  obtained from svn.python.org will always be pre-configured and ready
  to build.

* bpo-21037: Add a build option to enable AddressSanitizer support.

* bpo-19962: The Windows build process now creates “python.bat” in the
  root of the source tree, which passes all arguments through to the
  most recently built interpreter.

* bpo-21285: Refactor and fix curses configure check to always search
  in a ncursesw directory.

* bpo-15234: For BerkeleyDB and Sqlite, only add the found library and
  include directories if they aren’t already being searched. This
  avoids an explicit runtime library dependency.

* bpo-17861: Tools/scripts/generate_opcode_h.py automatically
  regenerates Include/opcode.h from Lib/opcode.py if the latter gets
  any change.

* bpo-20644: OS X installer build support for documentation build
  changes in 3.4.1: assume externally supplied sphinx-build is
  available in /usr/bin.

* bpo-20022: Eliminate use of deprecated bundlebuilder in OS X builds.

* bpo-15968: Incorporated Tcl, Tk, and Tix builds into the Windows
  build solution.

* bpo-17095: Fix Modules/Setup *shared* support.

* bpo-21811: Anticipated fixes to support OS X versions > 10.9.

* bpo-21166: Prevent possible segfaults and other random failures of
  python –generate-posix-vars in pybuilddir.txt build target.

* bpo-18096: Fix library order returned by python-config.

* bpo-17219: Add library build dir for Python extension cross-builds.

* bpo-22919: Windows build updated to support VC 14.0 (Visual Studio
  2015), which will be used for the official release.

* bpo-21236: Build _msi.pyd with cabinet.lib instead of fci.lib

* bpo-17128: Use private version of OpenSSL for OS X 10.5+ installer.


C API
-----

* bpo-14203: Remove obsolete support for view==NULL in
  PyBuffer_FillInfo(), bytearray_getbuffer(), bytesiobuf_getbuffer()
  and array_buffer_getbuf(). All functions now raise BufferError in
  that case.

* bpo-22445: PyBuffer_IsContiguous() now implements precise contiguity
  tests, compatible with NumPy’s NPY_RELAXED_STRIDES_CHECKING
  compilation flag.  Previously the function reported false negatives
  for corner cases.

* bpo-22079: PyType_Ready() now checks that statically allocated type
  has no dynamically allocated bases.

* bpo-22453: Removed non-documented macro PyObject_REPR().

* bpo-18395: Rename "_Py_char2wchar()" to "Py_DecodeLocale()", rename
  "_Py_wchar2char()" to "Py_EncodeLocale()", and document these
  functions.

* bpo-21233: Add new C functions: PyMem_RawCalloc(), PyMem_Calloc(),
  PyObject_Calloc(), _PyObject_GC_Calloc(). bytes(int) is now using
  "calloc()" instead of "malloc()" for large objects which is faster
  and use less memory.

* bpo-20942: PyImport_ImportFrozenModuleObject() no longer sets
  __file__ to match what importlib does; this affects
  _frozen_importlib as well as any module loaded using
  imp.init_frozen().


Documentation
-------------

* bpo-19548: Update the codecs module documentation to better cover
  the distinction between text encodings and other codecs, together
  with other clarifications. Patch by Martin Panter.

* bpo-22394: Doc/Makefile now supports "make venv PYTHON=../python" to
  create a venv for generating the documentation, e.g., "make html
  PYTHON=venv/bin/python3".

* bpo-21514: The documentation of the json module now refers to new
  JSON RFC 7159 instead of obsoleted RFC 4627.

* bpo-21777: The binary sequence methods on bytes and bytearray are
  now documented explicitly, rather than assuming users will be able
  to derive the expected behaviour from the behaviour of the
  corresponding str methods.

* bpo-6916: undocument deprecated asynchat.fifo class.

* bpo-17386: Expanded functionality of the "Doc/make.bat" script to
  make it much more comparable to "Doc/Makefile".

* bpo-21312: Update the thread_foobar.h template file to include newer
  threading APIs. Patch by Jack McCracken.

* bpo-21043: Remove the recommendation for specific CA organizations
  and to mention the ability to load the OS certificates.

* bpo-20765: Add missing documentation for PurePath.with_name() and
  PurePath.with_suffix().

* bpo-19407: New package installation and distribution guides based on
  the Python Packaging Authority tools. Existing guides have been
  retained as legacy links from the distutils docs, as they still
  contain some required reference material for tool developers that
  isn’t recorded anywhere else.

* bpo-19697: Document cases where __main__.__spec__ is None.


Tests
-----

* bpo-18982: Add tests for CLI of the calendar module.

* bpo-19548: Added some additional checks to test_codecs to ensure
  that statements in the updated documentation remain accurate. Patch
  by Martin Panter.

* bpo-22838: All test_re tests now work with unittest test discovery.

* bpo-22173: Update lib2to3 tests to use unittest test discovery.

* bpo-16000: Convert test_curses to use unittest.

* bpo-21456: Skip two tests in test_urllib2net.py if _ssl module not
  present. Patch by Remi Pointel.

* bpo-20746: Fix test_pdb to run in refleak mode (-R).  Patch by
  Xavier de Gaye.

* bpo-22060: test_ctypes has been somewhat cleaned up and simplified;
  it now uses unittest test discovery to find its tests.

* bpo-22104: regrtest.py no longer holds a reference to the suite of
  tests loaded from test modules that don’t define test_main().

* bpo-22111: Assorted cleanups in test_imaplib.  Patch by Milan
  Oberkirch.

* bpo-22002: Added "load_package_tests" function to test.support and
  used it to implement/augment test discovery in test_asyncio,
  test_email, test_importlib, test_json, and test_tools.

* bpo-21976: Fix test_ssl to accept LibreSSL version strings.  Thanks
  to William Orr.

* bpo-21918: Converted test_tools from a module to a package
  containing separate test files for each tested script.

* bpo-9554: Use modern unittest features in test_argparse. Initial
  patch by Denver Coneybeare and Radu Voicilas.

* bpo-20155: Changed HTTP method names in failing tests in
  test_httpservers so that packet filtering software (specifically
  Windows Base Filtering Engine) does not interfere with the
  transaction semantics expected by the tests.

* bpo-19493: Refactored the ctypes test package to skip tests
  explicitly rather than silently.

* bpo-18492: All resources are now allowed when tests are not run by
  regrtest.py.

* bpo-21634: Fix pystone micro-benchmark: use floor division instead
  of true division to benchmark integers instead of floating point
  numbers. Set pystone version to 1.2. Patch written by Lennart
  Regebro.

* bpo-21605: Added tests for Tkinter images.

* bpo-21493: Added test for ntpath.expanduser().  Original patch by
  Claudiu Popa.

* bpo-19925: Added tests for the spwd module. Original patch by
  Vajrasky Kok.

* bpo-21522: Added Tkinter tests for Listbox.itemconfigure(),
  PanedWindow.paneconfigure(), and Menu.entryconfigure().

* bpo-17756: Fix test_code test when run from the installed location.

* bpo-17752: Fix distutils tests when run from the installed location.

* bpo-18604: Consolidated checks for GUI availability.  All platforms
  now at least check whether Tk can be instantiated when the GUI
  resource is requested.

* bpo-21275: Fix a socket test on KFreeBSD.

* bpo-21223: Pass test_site/test_startup_imports when some of the
  extensions are built as builtins.

* bpo-20635: Added tests for Tk geometry managers.

* Add test case for freeze.

* bpo-20743: Fix a reference leak in test_tcl.

* bpo-21097: Move test_namespace_pkgs into test_importlib.

* bpo-21503: Use test_both() consistently in test_importlib.

* bpo-20939: Avoid various network test failures due to new redirect
  of http://www.python.org/ to https://www.python.org: use
  http://www.example.com instead.

* bpo-20668: asyncio tests no longer rely on tests.txt file. (Patch by
  Vajrasky Kok)

* bpo-21093: Prevent failures of ctypes test_macholib on OS X if a
  copy of libz exists in $HOME/lib or /usr/local/lib.

* bpo-22770: Prevent some Tk segfaults on OS X when running gui tests.

* bpo-23211: Workaround test_logging failure on some OS X 10.6
  systems.

* bpo-23345: Prevent test_ssl failures with large OpenSSL patch level
  values (like 0.9.8zc).


Tools/Demos
-----------

* bpo-22314: pydoc now works when the LINES environment variable is
  set.

* bpo-22615: Argument Clinic now supports the “type” argument for the
  int converter. This permits using the int converter with enums and
  typedefs.

* bpo-20076: The makelocalealias.py script no longer ignores UTF-8
  mapping.

* bpo-20079: The makelocalealias.py script now can parse the SUPPORTED
  file from glibc sources and supports command line options for source
  paths.

* bpo-22201: Command-line interface of the zipfile module now
  correctly extracts ZIP files with directory entries.  Patch by Ryan
  Wilson.

* bpo-22120: For functions using an unsigned integer return converter,
  Argument Clinic now generates a cast to that type for the comparison
  to -1 in the generated code.  (This suppresses a compilation
  warning.)

* bpo-18974: Tools/scripts/diff.py now uses argparse instead of
  optparse.

* bpo-21906: Make Tools/scripts/md5sum.py work in Python 3. Patch by
  Zachary Ware.

* bpo-21629: Fix Argument Clinic’s “–converters” feature.

* Add support for "yield from" to 2to3.

* Add support for the **PEP 465** matrix multiplication operator to
  2to3.

* bpo-16047: Fix module exception list and __file__ handling in
  freeze. Patch by Meador Inge.

* bpo-11824: Consider ABI tags in freeze. Patch by Meador Inge.

* bpo-20535: PYTHONWARNING no longer affects the run_tests.py script.
  Patch by Arfrever Frehtes Taifersar Arahesis.


Windows
-------

* bpo-23260: Update Windows installer

* The bundled version of Tcl/Tk has been updated to 8.6.3.  The most
  visible result of this change is the addition of new native file
  dialogs when running on Windows Vista or newer.  See Tcl/Tk’s TIP
  432 for more information.  Also, this version of Tcl/Tk includes
  support for Windows 10.

* bpo-17896: The Windows build scripts now expect external library
  sources to be in "PCbuild\..\externals" rather than "PCbuild\..\..".

* bpo-17717: The Windows build scripts now use a copy of NASM pulled
  from svn.python.org to build OpenSSL.

* bpo-21907: Improved the batch scripts provided for building Python.

* bpo-22644: The bundled version of OpenSSL has been updated to
  1.0.1j.

* bpo-10747: Use versioned labels in the Windows start menu. Patch by
  Olive Kilburn.

* bpo-22980: .pyd files with a version and platform tag (for example,
  “.cp35-win32.pyd”) will now be loaded in preference to those without
  tags.

**(For information about older versions, consult the HISTORY file.)**
