Issue #18942: sys._debugmallocstats() output was damaged on Windows.

_PyDebugAllocatorStats() called PyOS_snprintf() with a %zd format
code, but MS doesn't support that code.  Interpolated
PY_FORMAT_SIZE_T in place of the "z".
Improve urlencode docstring. Patch by Brian Brazil.
Issue #18939: Updated venv documentation with some clarifications.
Issue #18940: Handled low-volume logging when delay is True.
Issue #18941: Respected delay when doing rollover.
Issue #18849: Fixed a Windows-specific tempfile bug where collision with an
existing directory caused mkstemp and related APIs to fail instead of
retrying. Report and fix by Vlad Shcherbina.
Issue 18944:  fix a 1-character typo in test_set.py.

The error caused test_inline_methods() to test much less than intended.
Caught (& fixed) by Armin Rigo.