As said on the tin. Uses the system PAM so no dependencies.
The upcoming x11/cinnamon (and company) update depends on this for user management.
Patch is at review D18979. Passes testport and a rudimentary runtime check.
A commit references this bug:
Date: Wed Jan 30 19:06:56 UTC 2019
New revision: 491641
security/py-python-pam: create port
Python PAM module
Submitted by: Charlie Li <email@example.com>
Reviewed by: koobs
Differential Revision: https://reviews.freebsd.org/D18979