#11420: make test suite pass with -B/DONTWRITEBYTECODE set.  Initial patch by Thomas Wouters.
Issue #17418: specify that buffer sizes are bytes as soon as possible.
Merge heads 3.2.
Issue #16564: Fixed a performance regression relative to Python 3.1 in the
caching of compiled regular expressions.
Issue #16389: Fixed an issue number in previos commit.