The problem seems to have been that "/usr/bin/kdm-kde4" was in /etc/X11/default-display-manager, which neither matched the kdm-kde4 daemon ("/usr/lib/kde4/bin/kdm") nor the kdm one ("/usr/bin/kdm").
I've found another, related problem though: only using "sudo dpkg-reconfigure kdm-kde4" I was unable to change the login manager from kdm-kde4 back to kdm.
I'm attaching a patch to fix this.
The problem seems to have been that "/usr/bin/kdm-kde4" was in /etc/X11/ default- display- manager, which neither matched the kdm-kde4 daemon ("/usr/ lib/kde4/ bin/kdm" ) nor the kdm one ("/usr/bin/kdm").
I've found another, related problem though: only using "sudo dpkg-reconfigure kdm-kde4" I was unable to change the login manager from kdm-kde4 back to kdm.
I'm attaching a patch to fix this.