https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=225742
Additional port changes:
- DISTVERSION
- Added dependencies:
- mail/py-authres
- mail/py-milter (unfortunately py27-only)
- security/py-pynacl
- Replaced dependencies:
- dns/py-dns -> dns/py-dnspython (allows py36 now)
- Added USE_PYTHON=concurrent.
- Added patch fixing manpage path.