Comment # 5 on bug 933043 from James Fehlig

Thanks.  I went with the 'systemd_version' variant even though it wouldn't
detect if Socket{User,Group} was backported since I doubt that would also
include a version change.

I've submitted the fix to Virtualization/libvirt (for next Factory checkin),
submitted a maintenancereq for 13.2 (MR#310184), and included the fix in most
recent submission for SLE12 SP1 (SR#59276).