GNOME session restarted during upgrade; tracking down buggy package

[josh at joshtriplett.org]

On Thu, Jul 09, 2015 at 12:59:27PM -0700, josh at joshtriplett.org wrote:
> I just tried to upgrade a set of packages, and at some point during the
> upgrade, GNOME restarted, losing my current session.  I'm trying to
> track down which package to file the bug against, as I'm not sure if it
> lies in GNOME, some systemd component, or some dbus service.  I could
> use some help narrowing it down to the right package or packages.
> 
> I've attached the list of upgraded packages and versions from /var/log/aptitude
> as "pkgs", and the relevant section of the journal as "log".  The log
> starts from around the time the upgrade caused systemd to re-execute
> itself to the point where gdm3 has restarted and started to bring up a
> new X session.
> 
> I don't know if the issue lies with some systemd component (like logind
> or udev), with some dbus service, with some GNOME component for not
> handling service restarts, or somewhere else entirely.

I can reproduce this with a much smaller upgrade: I downgraded just gdm3 and
its dependencies libgdm1 and gir1.2-gdm3 to 3.14.1-8, rebooted, then
re-upgraded those three packages to 3.14.2-1.  During "Setting up gdm3", my
GNOME session restarted.

Here's the complete log from /var/log/apt/term.log:

Log started: 2015-07-09  16:50:32
[... snip "Reading database" progress messages and resulting terminal noise. ...]
Preparing to unpack .../gdm3_3.14.2-1_amd64.deb ...
Unpacking gdm3 (3.14.2-1) over (3.14.1-8) ...
Preparing to unpack .../libgdm1_3.14.2-1_amd64.deb ...
Unpacking libgdm1 (3.14.2-1) over (3.14.1-8) ...
Preparing to unpack .../gir1.2-gdm3_3.14.2-1_amd64.deb ...
Unpacking gir1.2-gdm3 (3.14.2-1) over (3.14.1-8) ...
Processing triggers for systemd (222-1) ...
Processing triggers for dbus (1.8.18-1) ...
Processing triggers for libglib2.0-0:amd64 (2.44.1-1.1) ...
Processing triggers for man-db (2.7.0.2-5) ...
Processing triggers for hicolor-icon-theme (0.13-1) ...
Setting up libgdm1 (3.14.2-1) ...
Setting up gir1.2-gdm3 (3.14.2-1) ...
Setting up gdm3 (3.14.2-1) ...
[at this point my session restarted]
Processing triggers for libc-bin (2.19-18) ...
Log ended: 2015-07-09  16:50:35