Issue #11302: missing type check on _string.formatter_field_name_split and _string.formatter_parser caused crash.

Originial patch by haypo, reviewed by me, okayed by Georg.

Add bullet list and reference to documentation section.

Added a placeholder for str.format_map, as discussed with Raymond. My prose is horrible, some cleanup is required.

Minor internal change to unittest.TestCase.assertCountEqual
Reviewed by R. David Murray

conversion.

(Patch reviewed by David Murray.)

Found by Nadeem Vawda, reviewed by Brett.

Bug discovery and initial patch by Victor Stinner.

keyword-only argument.  The preceding positional argument was deprecated,
so it made no sense to add filter as a positional argument.

(Patch reviewed by Brian Curtin and Anthony Long.)

Parser => BytesParser

(Reviewed by Georg Brandl.)

Also made similar changes to deque.reverse() though this wasn't
strictly necessary (the edge case cannot occur with two pointers
moving to meet in the middle).  Making the change in reverse()
was more a matter of future-proofing.

run with tracing turned on.

        with non-ASCII characters in their path names.

        (with approval of release manager for 3.2rc2)

Issue #9509: make argarse properly handle IOErrors raised by argparse.FileType. Approved by Georg in the tracker.