Bug#801749: gdm3: Does not start anymore

[Floris]

Same problem here. Updating gdm3 to 3.18 results in a flickering screen.  
(the X server is started over and over again)
The output of journalctl -b is here:
http://www.jkfloris.dds.nl/gdm3-update
After downgrading to 3.14 (testing) gdm3 does show the login prompt, but  
gnome does not load.

Output journalctl -b:
http://www.jkfloris.dds.nl/gdm3.14

So back to gnome 3.14

floris