Comment # 28 on bug 934901 from Egbert Eich

On a VT switch the Xserver gives up DRM master so that another Xserver can
obtain it. When switching back, it cannot become DRM master any more without
the help of systemd-logind if it is not running as root.

I've discussed this with Hans de Goede over dinner at FOSDEM: 
He had discussed this issue extensively with Lennard: 
1. systemd-logind should have at least the lifetime of the Xserver if not of
the 
   system. Its restart should be delayed during an update unless it is clear no 
   Xserver is running. (Maybe by checking the pids in /tmp/.X*-lock for mapping 
   /usr/bin/Xorg:
   ls -l /proc/$xpid/map_files/ | grep -q "/usr/bin/Xorg").
   There is in fact no reason to restart it unless there is a security issue 
   somewhere.
2. systemd-logind should not crash: it is a simple enough application (much 
   simpler than the Xserver), if it crashes it is tantamount to the Xserver 
   crashing.
3. Anything we can do on the side of the Xserver will be kludgey.

I would therefore like to close this ticket now with the fix we currently have.