The tests now pass all combinations of -O/-OO and -B.  See also #7071
and #6292 for previous variations on the same theme.

test_versionpredicate needs a skip when sys.flags.optimize is true, but
I don’t know how to make that work with a DocTestSuite.

Patch by Mher Movsisyan.

Mac OS X and FreeBSD to reduce the chances of a crash instead of a
"maximum recursion depth" RuntimeError exception.
(patch by Ronald Oussoren)

the file is closed.

their encode() method anymore, but continue to call the reset() method if the
final argument is True.

to be able to unload the module.

3.2 (#10801: In zipfile, support different encodings for the header and the
filenames.  Patch by MvL, test by Eli Bendersky.)

different encodings for the header and the filenames.  Patch by MvL, test by
Eli Bendersky.

On MacOSX and OpenBSD (and possibly other BSDs) "en_US.UTF-8" is a valid locale
while "en_US.UTF8" is not. As the former works on Linux as well it is better
to normalize to that value.