Closes #13402.

a random deadlock when fork() is called in a multithreaded process in debug
mode, and make PyOS_AfterFork() more robust.

Fedora buildbot.

Closes #13676.

to PyShell.PyShell.transfer_path() and changing elsewhere as needed.
Original patches by Marco Scataglini and Roger Serwy.

Issue #13806: The size check in audioop decompression functions was too strict and could reject valid compressed data.
Patch by Oleg Plakhotnyuk.

Issue #13889: Add missing _Py_SET_53BIT_PRECISION_* calls around uses of dtoa.c functions in float round.

(rather than `-m test.regrtest`)