Behavior equivalent to m.configure_mock().  Patch by Kasia Jachim.

Patch by Stéphane Wirtel.

(closes #18147)

   party sources. Run aclocal to import it to aclocal.m4 and add aclocal.m4
   to the archive.

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.

Using LF can a script to fail if it tries to use a label that is
split across 512 byte blocks.  Who knows why.

Patch by Juti Noppornpitak.

It's still not necessary to build, but may be useful to some.

Patch by James Powell.

Patch by Martin Panter.

Close #23904: fix pathlib documentation misleadingly mentioning that bytes objects are accepted in the PurePath constructor

Patch by James Edwards.

Patch by Alex Gaynor.

TestHelpVersionOptional was redundant.

robust at shutdown. If needs to release multiple resources, they are released
even if errors are occured.

This will prevent failures from the version of NASM installed on buildbots,
if the ability to override the version used is desired again later, we can
figure out a way to opt in.