Bug#285151: more info
oops, that bug report was cut out in the middle.
Any way, after upgrading to version 4.3.0.dfsg.1-9 of xdm, xdm doesn't
start the X server. Meaning noone can connect the the GUI. Killing XDM and
running startx works.
I tried to downgrade to version 4.3.0.dfsg.1-8 and the problem was solved.
I also diff the file betwwen version 4.3.0.dfsg.1-8 & 4.3.0.dfsg.1-9 and
didn't find any big difference. sorry.