.. bpo: 45121
.. date: 2021-09-07-17-10-16
.. nonce: iG-Hsf
.. release date: 2021-10-04
.. section: Core and Builtins

Fix issue where ``Protocol.__init__`` raises ``RecursionError`` when it's
called directly or via ``super()``. Patch provided by Yurii Karabas.

..

.. bpo: 45234
.. date: 2021-09-17-11-20-55
.. nonce: qUcTVt
.. section: Library

Fixed a regression in :func:`~shutil.copyfile`, :func:`~shutil.copy`,
:func:`~shutil.copy2` raising :exc:`FileNotFoundError` when source is a
directory, which should raise :exc:`IsADirectoryError`

..

.. bpo: 45216
.. date: 2021-09-18-13-45-19
.. nonce: o56nyt
.. section: Documentation

Remove extra documentation listing methods in ``difflib``. It was rendering
twice in pydoc and was outdated in some places.

..

.. bpo: 45024
.. date: 2021-09-08-17-20-19
.. nonce: dkNPNi
.. section: Documentation

:mod:`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 :term:`special method`\s. Patch by Raymond Hettinger.

..

.. bpo: 45128
.. date: 2021-09-16-17-22-35
.. nonce: Jz6fl2
.. section: Tests

Fix ``test_multiprocessing_fork`` failure due to ``test_logging`` and
``sys.modules`` manipulation.

..

.. bpo: 44860
.. date: 2021-09-08-13-01-37
.. nonce: qXd0kx
.. section: Tests

Update ``test_sysconfig.test_user_similar()`` for the posix_user scheme:
``platlib`` doesn't use :data:`sys.platlibdir`. Patch by Victor Stinner.

..

.. bpo: 45067
.. date: 2021-09-09-16-45-26
.. nonce: mFmY92
.. section: Build

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.

..

.. bpo: 45193
.. date: 2021-09-15-03-20-06
.. nonce: G61_GV
.. section: IDLE

Make completion boxes appear on Ubuntu again.

..

.. bpo: 45307
.. date: 2021-09-28-12-00-55
.. nonce: 3ETFfX
.. section: C API

Restore the private C API function :func:`_PyImport_FindExtensionObject`. It
will be removed in Python 3.11.