authwatch spawns its own dbus

[jdreed]

On Precise cluster, I consistently end up with two dbus-daemons. One from dbus-launch (And the normal xsession), the other is spawned by authwatch, because we run xsession.bash (or tcsh) before the session is launched. So authwatch comes up, wants dbus for some reason (gtk?), and not having a valid address, dbus autolaunches its own bus. It's possible that authwatch should move to xdg/autostart or something. Starting zwgc is probably wrong too.

[jdreed]

We have a couple of options here:

• Turn off use_session_dbus in Xsession.options and let dbus just autostart itself. dbus-launch, hilariously, ignores DBUS_SESSION_ADDRESS, but will check for ~/.dbus/session-bus/(machine id) and try and connect to that bus. (That's a text file with the bus address, not a socket). So that will "just work", and dbus will come up when it's needed. (Which is, like, the point of dbus-launch).
• Start a bus manually in the session wrapper, and set DBUS_SESSION_ADDRESS.
• Stop spawning processes in the Xsession.d scripts. This would entail us moving the logic from /usr/lib/init/xsession.* to something started by an xdg autostart file. This is arguably the Right(tm) way, but requires a few more changes. I don't think our xsession _needs_ to wrap the actual session any more. This will require a bit of thought.