Bug#766241: gnome: dist-upgrade on 20-Oct lost gnome pixbufs and several tweak settings reset

[Jim Cobley]

"Being able to login in text mode means that the "whole system" is not 
broken => downgrading the severity a little bit."
Just a very little bit!

"What exactly makes you unable to login? Do you see a graphical login 
screen at all?"
I got the graphical login, press space, enter password and then - as far 
as I remember - just a blank graphical screen with top bar.
Clicking on icons on RHS of top bar gave, again remembering is tricky 
now, just an empty black box.

This looks like:
     https://bugs.debian.org/761001
             - sounds similarish!
     https://bugs.debian.org/759745
             - not really

Do the symptoms look like what you've seen? See above but I wouldn't 
really say so!
I think that the fact that the icon cache was empty and that appeared to 
be the cause means that this problem may have been different from those 
mentioned above.

Are you running systemd as pid 1? Yes it is

Do you have the systemd-shim package installed? No
Never heard about the shim until now - "Packages" shows systemd and 
systemd-sysv are loaded but systemd-shim is not

I was going to switch between GDM and LightGDM but I couldn't remember 
how - therefore I booted into Ubuntu instead to google it and found 
several suggestions for the problem - such as the recreation of the 
cache icons ( RedHat bug 912303). Checked the Debian icon cache folder 
and it was empty.
Tried that first and the system recovered so I didn't need to do 
anything else and quickly forgot exactly what happened. Very lucky 
choice I think.