So it seems gdm is buggy there, the prerm sets the default to "lightdm" rather the to "/usr/sbin/lightm", lightdm has a similar bug since its script is copied from gdm...
So it seems gdm is buggy there, the prerm sets the default to "lightdm" rather the to "/usr/sbin/lightm", lightdm has a similar bug since its script is copied from gdm...