This was found by PVS-Studio:

V595 The 'def' pointer was utilized before it was verified
against nullptr. Check lines: 286, 292. pystate.c 286

Initial patch by Christian Heimes.

Issue #27539: Fix unnormalised Fraction.__pow__ result for negative exponent and base. Thanks Vedran Čačić.

According to PEP 249, cursor.description must be
available for any SELECT statements, such as those
that use CTEs.

Backported from https://github.com/ghaering/pysqlite/commit/f67fa9c898a4713850e16934046f0fe2cba8c44c

Additional test cases added by me.

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.

Also try to clarify the find_spec() error message.

bootstrap files:
    Could not find platform dependent libraries <exec_prefix
    Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
Patch by Xiang Zhang

Issue #27128. Fix a reference leak if creating the tuple to pass positional
parameters fails.

Issue #27128. Fix a reference leak if creating the tuple to pass positional
parameters fails.

Patch by Robin Roth, reviewed by Serhiy Storchaka, comment wording
tweaked by me.

Issue #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.

sys.version[0] gives a string, which fails > comparison with 2.
Reported by Arne Maximilian Richter on docs@

* Memove -t option of ctags. The option was kept for backward compatibility,
  but it was completly removed recently. Patch written by Stéphane Wirtel.
* Set locale to C to call sort. vim expects that the tags file is sorted using
  english collation, so it fails if the locale is french for example. Use
  LC_ALL=C to force english sorting order. .

If Popen.communicate() raises an exception, kill the child process to not leave
a running child process in background and maybe create a zombi process.

This change fixes a ResourceWarning in Python 3.6 when unit tests are
interrupted by CTRL+c.

rearrange methodcaller_new so that the main error case does not cause uninitialized memory usage (closes #27783)

_is_data_descriptor().

The original problem has been fixed in newer versions of FreeBSD.
Patch by Dimitry Andric of the FreeBSD project.

Patch by Ronald Oussoren.