Patch by Aaron (hac.man).

from previous checkin.

new parameters in os and shutil functions.  Patch by Serhiy Storchaka.

Update the pkgutil porting section in What's New. This should cause significantly fewer problems after today's updates

Note why we can't write an automated test for the code path that brings up the REPL for a bare 'python' call

Take the first step in resolving the messy pkgutil vs importlib edge cases by basing pkgutil explicitly on importlib, deprecating its internal import emulation and setting __main__.__loader__ correctly so that runpy still works (Affects #15343, #15314, #15357)

Issue #9458: clarify the documentation of ElementTree.write with regards to the type of the stream expected for a given encoding

Close #1767933: Badly formed XML using etree and utf-16. Patch by Serhiy Storchaka, with some minor fixes by me

  the atexit module will be called in a deterministic order.

with it a vareity of bug fixes, both security and behavior.  See
http://www.libexpat.org/ for the list.

NOTE: I already backported the expat hash randomization fix in March.

Fixes issue #14340.

Close #15230: runpy.run_path now sets __package__ correctly. Also refactored the runpy tests to use a more systematic approach

tempfile directory path (i.e. on OS X /tmp is actually /private/tmp).

Patch by Jeremy Kloth.

Patch by Jeremy Kloth.

Issue #15338: skip test_UNC_path when the current user doesn't have enough permissions to access the path.