puppetlabs/facter — pull request #514 by apenney (2013-08-12 17:00:59+00:00)
Title: (#22143) Add 'gid' fact to resolve users primary group.

A very simple fact to fetch the primary group. I've only tested
this on Linux/OSX/FreeBSD but id -ng seems to be global. I even
got a user to test it on Hurd and it worked.