Comment 12 for bug 1497473

Steve, you asked:

1. But the glibc package doesn't overwrite anything that belongs to the
xserver-xorg package, and the xserver-xorg package contains no relevant
maintainer scripts so reinstalling it would have no effect.

2. Also, why are you installing glibc from wily-proposed?

Well, for the point 2:
The reason to use the proposed is exactly what happened with glibc 2.22 - testing and finding the bugs, so that it others do not have to break their setups.

To the question 1:
I did test several times and each time reinstalling xserver (packages xserver-common and xserver-xorg-core) did help.
I tried this in the first place because, after upgrading into glibc 2.22 I could get into tty1.
Not even if I downgraded back into glibc 2.21.
So, the setup was not badly borked, it was only the X that did not start. The command startx did not work either.

Finally, whatever the true reason for this bug is, reinstalling xserver-xorg-core (after downgrading into glibc 2.21) fixes it.
I have now a fully working setup, with glibc 2.21.