I tried to restart gnome-shell this evening with Alt-F2 r RET, and
it
crashed on restart. Then it crashed again when I tried to log in again. Then
several more times. Then again after I restarted.
Seeing as how I had no other choice if I wanted to actually log in, I
downloaded and installed all of the debuginfos in a VT, debugged the crash,
and came up with a fix, which I've submitted as a patch in bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=810053
I noticed that the notification that bugzilla sent out about this bug went
to a rather paltry list of people. I'm therefore sending this email to the
test list in the hope that it will be noticed by someone in a position to
ensure that this bug is fixed in the final F17 release, so that other people
who don't actually know how to analyze core dumps and fix bugs won't end up
completely unable to log in.