MDM support for casper

I use remastersys (yes I know it isn't supported anymore, but it still works fine with 14.04 trusty) to make custom ISOs.

Last week after doing a "dist-upgrade" and then running remastersys, the resulting ISOs, would go to a login screen when starting the Live Session instead of booting all the way to the Live Session desktop.

I have done this process many times for Ubuntu 14.04, and never had this problem, even though a google search will show several others in the past have had this issue. You can get around the login screen by using the remastersys ID from /etc/remastersys.conf and a password of <blank>, but this didn't work all the time for me (I think it is fairly reliable with lightdm, but we use mdm from LinuxMint, which would not accept the blank password and would stay "stuck" at the login screen).

After a lot of trial and error in trying to isolate what changed, I have found that casper 1.340.2 is the source of the problem. If I "hold" casper at 1.340 like this:

apt-mark hold casper ubiquity-casper

After applying this command to my test machine, and then doing a dist-upgrade, and then running remastersys, the resulting ISOs boot correctly to the Live Session desktop.

If, however, casper updates to 1.340.2, the resulting ISOs will go to the login screen and get stuck.

I have attempted to scan the changes to casper and am not able to understand what is causing the problem, but it definitely is something to do with casper 1.340.2.