Comment 14 for bug 75602

Here's a mailing list thread that alluded to this bug:
http://lists.freedesktop.org/archives/dbus/2013-February/015505.html

The idea is to at least try harder on Linux where relevant user/group information can be extracted from procf status file.

I'll be sending some patches here for review to see if it's plausible to take this approach.