I have not received any responses since my first post in this thread in September last year. This time I am adding python-dev to BCC in hopes to reach a larger audience. With the date of the first beta (2016-09-07) fast approaching, I would like to commit PEP 495 implementation hopefully before alpha 3 (2016-07-11).
I have a patch published as a pull request  against the python/cpython repository on github. If anyone still prefers the bug tracker workflow, I can publish it as a patch for issue #24773  as well.
Please also see my post from March below. Since that post, I have implemented a -utzdata option to the regression test, so now the long exhaustive test only runs when you do python -mtest -utzdata. Note that this test currently fails on a couple exotic timezones such as Asia/Riyadh87, but it is likely to be an issue with the timezone database rather than python code. I still don't have access to a Windows development box and I know that the current implementation will not work there because I use localtime_r. I need help/advise on this front.
I have not started updating the documentation, so the PEP text  should serve as the documentation for now. I will try to get the documentation patch ready before the beta, but I don't want to delay checking in the code.
On Mon, Mar 21, 2016 at 10:34 PM, Alexander Belopolsky < email@example.com> wrote:
I am getting close to completing PEP 495 implementation, but I need
someone to help me with a port to Windows. One of the major obstacles is that my implementation relies heavily on the POSIX localtime_r function which apparently is not available on Windows.
I would also appreciate help from a unittest expert to improve
test_datetime. One of the pressing tasks is to make ZoneInfoCompleteTest optional because it takes several minutes to complete.
I am maintaining the patch as a pull request  against the
python/cpython repository on github. Code reviews are most welcome.