"ours" merge to avoid version bump

"ours" merge to avoid cherry-picked copy of #25512 fix, which is already in
this branch.

Fixes bug 25512.

(Cherry-picked from 3519d0c8

This reverts part of commit 6ed384b8, in order to
fix bug 26568.  Bugfix on 0.3.4.1-alpha.

Recent Python3 versions seem to require this on Windows.

Fixes bug 26535; bug copied from ntor_ref.py on 0.3.1.1-alpha.

Recent Python3 versions seem to require this on Windows.

Fixes bug 26535; bug introduced in f4be34f7, which
was apparently intended itself as a Python3 workaround.

This check was added by mistake long ago.  It will be nice to see
these EOLs disappear from our code over time.

(backport from master)