Issue #21171: Fixed undocumented filter API of the rot13 codec.
Patch by Berker Peksag.
Issue #20635: Added tests for Tk geometry managers.
#21169: fix getpass to use replace error handler on UnicodeEncodeError.

If the input stream encoding couldn't encode one or more of the
non-ascii characters in the prompt, it would fail, throwing a
UnicodeEncodeError.  Now if that happens we re-encoding using the
'replace' error handler.

Patch by Kushal Das.
in scan_once, prevent the reading of arbitrary memory when passed a negative index

Bug reported by Guido Vranken.
merge 3.2
merge 3.3
fix sending tuples to custom generator objects with yield from (closes #21209)

Debugged by Victor.