Fixes bug 25512.

(Cherry-picked from 3519d0c8

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)

Bug not in any released Tor.

Found by asan on travis :/