#15438: add a note to math.pow() that suggests using **/pow() for integers.  Patch by Mark Dickinson.
#15438: merge with 3.2.
#15438: merge with 3.3.
#17249: convert a test in test_capi to use unittest and reap threads.
#17249: merge with 3.2.
#17249: merge with 3.3.
#17249: check for the availability of the thread module.
#17249: null merge.
#17249: null merge.
#17217: fix UnicodeEncodeErrors errors in test_format by printing ASCII only.
#17217: merge with 3.2.
#17217: merge with 3.3.
#12749: add a test for non-BMP ranges in character classes.
#12749: merge with 3.3.
Remove unused defines.
Remove unused defines.