[PATCH 3 of 3] py3: allow run-tests.py to run on Windows

[Yuya Nishihara]

On Sat, 15 Sep 2018 00:31:37 -0400, Matt Harbison wrote:
> # HG changeset patch
> # User Matt Harbison <matt_harbison at yahoo.com>
> # Date 1536984246 14400
> #      Sat Sep 15 00:04:06 2018 -0400
> # Node ID 757f2fe237ea1f72d75ff29bd1bb428db38813be
> # Parent  289c7157ec4510c619e9e7fdd9ac4995e13ce73e
> py3: allow run-tests.py to run on Windows

Queued with some check-code fixes, thanks.

> I have no idea why these changes are needed, given that it runs on Linux.  But
> os.system() is insisting that it take a str, and subprocess.Popen() blows up
> without str:

That's probably because a byte string is the native data structure on Unix.
Unicode story of Python 3 is horrible in many ways.