(the encoder already accepts them).

(the encoder already accepts them).

list and dict objects.  They already cleared other freelists in the
interpreter.

Patch by John O'Connor.

(backport of 6b9f547e92d8)

This fixes a subsequent refleak in test_smtplib.

Remove a sleep to fix transient test failures. Use skewfactor of -3 to
make it work on systems that have 1 second precision for time.time().

Closes #11999
Refs #13254

packaging.manifest.Manifest under Windows.  The "recursive-include"
directive now recognizes both legal path separators.