Cherrypicking fixed for new python syntax into the emacs 25 branch

[Nathaniel Smith <njs@pobox.com>]

[not subscribed to list, would appreciate CC's on followups]

Hi all,

Currently, the version of python.el in the emacs 25 branch doesn't
support the new async/await syntax added in python 3.5. This added new
syntax for basic syntactic constructs like function definitions and
for loops, and so currently in the emacs 25 branch anyone using these
new features loses basic features like autoindentation, e.g.

async def f():
async for x in ...:

are not considered to open blocks and require manual indentation. And
even worse, since the indentation tables are defined as compile-time
macros, it isn't even possible to fix this with a .emacs tweak.

This has already been fixed in emacs mainline. Would it be possible
for the emacs 25 branch maintainers to cherry-pick these two changes
into emacs 25?:
    1f6b0bc1
    928f5194

(some more discussion here: https://github.com/jorgenschaefer/elpy/issues/848)

Thanks!
-n

-- 
Nathaniel J. Smith -- https://vorpus.org