Use volatile keyword to disable localy unsafe float optimizations.

time.ctime(), gmtime(), time.localtime(), datetime.date.fromtimestamp(),
datetime.datetime.fromtimestamp() and datetime.datetime.utcfromtimestamp() now
raises an OverflowError, instead of a ValueError, if the timestamp does not fit
in time_t.

datetime.datetime.fromtimestamp() and datetime.datetime.utcfromtimestamp() now
round microseconds towards zero instead of rounding to nearest with ties going
away from zero.

Patch by Tatiana Al-Chueyr.

Tkinter.Variables; harmonize exceptions to ValueError; only delete variables
that have not been deleted; assert that variable names are strings
Patch by Andrew Svetlov.

Contrary to the documentation, finditer() did not take pos and endpos
keyword arguments.

patch written by Nicholas Riley.

str.format_map tests don't do what they say: fix to actually implement the intent of the test. Closes #13450. Patch by Akira Li.

str.format_map tests don't do what they say: fix to actually implement the intent of the test. Closes #13450.

#13394: add more tests for the aifc module and use warnings.warn instead of print.  Patch by Oleg Plakhotnyuk.

Thanks for James Sanders for the bug report and the patch.