Hi,

I can confirm that I am affected by this bug too.

My lightdm.conf says this:
[SeatDefaults]
user-session=gnome-shell
autologin-user=matthew
autologin-user-timeout=0
greeter-session=unity-greeter

But when I log in, /var/log/lightdm/lightdm.log states: 


[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.0.6, UID=0 PID=10997
[+0.00s] DEBUG: Loaded configuration from /etc/lightdm/lightdm.conf
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: Registered seat module xlocal
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Adding default seat
[+0.00s] DEBUG: Starting seat
[+0.00s] DEBUG: Starting new display for automatic login as user matthew
[+0.00s] DEBUG: Starting local X display
[+0.00s] DEBUG: Using VT 7
[+0.00s] DEBUG: Activating VT 7
[+0.00s] DEBUG: Logging to /var/log/lightdm/x-0.log
[+0.01s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0
[+0.01s] DEBUG: Launching X Server
[+0.01s] DEBUG: Launching process 11001: /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.01s] DEBUG: Waiting for ready signal from X server :0
[+0.01s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.01s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+0.78s] DEBUG: Got signal 10 from process 11001
[+0.78s] DEBUG: Got signal from X server :0
[+0.78s] DEBUG: Connecting to XServer :0
[+0.78s] DEBUG: Automatically logging in user matthew
[+0.79s] DEBUG: pam_start("lightdm-autologin", "matthew") -> (0xb099a0, 0)
[+0.79s] DEBUG: pam_authenticate(0xb099a0, 0) -> 0 (Success)
[+0.79s] DEBUG: pam_acct_mgmt(0xb099a0, 0) -> 0 (Success)
[+0.79s] DEBUG: User matthew authorized
[+0.80s] DEBUG: Using session ubuntu
[+0.80s] DEBUG: Starting user session
[+0.81s] DEBUG: Dropping privileges to uid 1000
[+0.81s] DEBUG: Restoring privileges
[+0.81s] DEBUG: Dropping privileges to uid 1000
[+0.81s] DEBUG: Writing /home/matthew/.dmrc
[+0.85s] DEBUG: Restoring privileges
[+0.87s] DEBUG: Starting session ubuntu as user matthew
[+0.87s] DEBUG: Logging to /home/matthew/.xsession-errors
[+0.87s] DEBUG: Launching session
[+0.87s] DEBUG: pam_set_item(0xb099a0, 3, ":0") -> 0 (Success)
[+0.87s] DEBUG: pam_open_session(0xb099a0, 0) -> 0 (Success)
[+0.90s] DEBUG: Opened ConsoleKit session 3e924aabbe6a65f6b372503900000010-1330695884.447217-1893360978
[+0.90s] DEBUG: Dropping privileges to uid 1000
[+0.90s] DEBUG: Adding session authority to /home/matthew/.Xauthority
[+0.93s] DEBUG: Restoring privileges
[+0.93s] DEBUG: Launching process 11013: /usr/sbin/lightdm-session '/usr/bin/gnome-session --session=ubuntu'
[+0.94s] DEBUG: New display ready, switching to it
[+0.94s] DEBUG: Activating VT 7
[+0.94s] DEBUG: pam_setcred(0xb099a0, PAM_ESTABLISH_CRED) -> 0 (Success)
[+0.94s] DEBUG: PAM returns environment 'PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games LANG=en_GB.UTF-8 LANGUAGE=en_GB:en'
[+0.94s] DEBUG: Registering session with bus path /org/freedesktop/DisplayManager/Session0


As you can see, there is some confusion somewhere and it's getting the wrong session type from somewhere. I know I can work around it by changing the ubuntu session type so that it loads gnome-shell, but that might break something in the future. Could someone please look at this?