Bug#874529: Additional logs and dbus transaction.

[Eliot Blennerhassett]

I don't think this is Mate-specific.  I'm seeing it with regular Gnome
desktop.

This issue discusses the same problem.
https://github.com/linuxmint/cinnamon-screensaver/issues/221

The seat name, which should be "seat0" is "seat0allow-timed-login"
I have spent a couple of hours trawling through source code (online),
but haven't reached a conclusion.

I recorded this information when the problem occurs.

>From journal:
Sep 20 16:36:18 eliot gdm-launch-environment][5815]:
pam_unix(gdm-launch-environment:session): session opened for user
Debian-gdm by eliot(uid=0)
Sep 20 16:36:18 eliot gdm-launch-environment][5815]:
pam_systemd(gdm-launch-environment:session): Failed to create session:
No seat 'seat0allow-time

>From dbus-monitor:

method call time=1505903552.055414 sender=:1.2159 ->
destination=org.freedesktop.login1 serial=2
path=/org/freedesktop/login1; interface=org.freedes
ktop.login1.Manager; member=CreateSession
   uint32 120
   uint32 26182
   string "gdm-launch-environment"
   string "x11"
   string "greeter"
   string ""
   string "seat0allow-timed-login"
   uint32 0
   string "/dev/tty2"
   string ""
   boolean false
   string ""
   string ""
   array [
   ]
method call time=1505903552.055571 sender=:1.2 ->
destination=org.freedesktop.DBus serial=11645
path=/org/freedesktop/DBus; interface=org.freedesktop.DBus;
member=GetConnectionUnixUser
   string ":1.2159"
method return time=1505903552.055612 sender=org.freedesktop.DBus ->
destination=:1.2 serial=4321 reply_serial=11645
   uint32 0
error time=1505903552.055699 sender=:1.2 -> destination=:1.2159
error_name=org.freedesktop.login1.NoSuchSeat reply_serial=2
   string "No seat 'seat0allow-timed-login' known"