Bug#789118: Cannot unlock screen after upgrading GNOME if locked before upgrade

[Simon McVittie]

Control: clone 789118 -2
Control: retitle 789118 Cannot unlock screen after upgrading: Type of message, '(sssssssb)', does not match expected type '(sssssssbb)'
Control: retitle -2 Cannot unlock screen after upgrading: Error: can't convert this._frame to an integer
Control: reassign -2 gnome-shell 3.14.4-1

On Wed, 25 Jan 2017 at 12:52:13 +0000, Simon McVittie wrote:
> On Sun, 11 Oct 2015 at 15:48:10 -0700, Josh Triplett wrote:
> > gnome-session[551]: (gnome-shell:956): Gjs-WARNING **: JS ERROR: Failed to start verification for user: Gio.DBusError: GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: Type of message, '(sssssssb)', does not match expected type '(sssssssbb)'
> 
> This is really a gdm3 issue

Using #789118 to represent this. My patch can fix this by being applied
to stretch, although I seem to have got the preinst logic wrong:
/run/gdm3-upgraded-from-debian-8 didn't get created and I had to do that
by hand.

On Wed, 25 Jan 2017 at 14:13:36 +0000, Simon McVittie wrote:
> I think this might be caused by gnome-shell raising an exception when
> it fails to load an animation, with the traceback below, and the PAM
> conversation not proceeding because gnome-shell is no longer talking
> to the gdm-session-worker as a result of that exception.
...
> That looks like https://bugzilla.redhat.com/show_bug.cgi?id=1350303
> which is some sort of install-order issue, or possibly the existing
> gnome-shell trying to use the old pixbuf loader cache that has been
> invalidated in the meantime by upgrading.
> 
> There is a workaround for that bug in stretch's gnome-shell, added
> by <https://bugzilla.gnome.org/show_bug.cgi?id=774805>;
> but of course during a live upgrade we're still dealing with jessie's
> gnome-shell, not stretch's, so we can't fix bugs.

Using the cloned bug to represent this, and reassigning back to gnome-shell.
This is going to be really difficult to fix unless we can find the
underlying issue (in gdk-pixbuf?), because it's difficult to get a
gnome-shell with the workaround deployed on the to-be-upgraded system
*before* doing the upgrade.

    S