The py2-ipaddress module unfortunately conflicts with the pypi:ipaddress module, which is in the dependency tree of widely used pyOpenSSL. I think it would be a good idea to use a well maintained backport of the Python 3.5 implementation of match_hostname() instead of duplicating the effort and maintain another.

All tests are passing here.
Signed-off-by: Felix Yan <felixonmars@archlinux.org>