data: Enable clean session shutdown after gnome-shell failure
If the GNOME shell crashes, we run a service that may disable extensions. This is important so that users will not be locked out of their own session in case an extension is causing crashes.
As this is a very agressive action, we only do so if the session fails in the first two minutes. The logic to do so was broken though, and would result in an unclean session shutdown.
Fix this by using the newly introduced file %t/gnome-session-stable and using a ConditionPathExists. This avoids any depenencies and therefore can cleanly run in parallel to a normal session shutdown.
Note that it is not a regression to do this even if the gnome-session part is not yet installed on the system. The result will be to always disable the extensions rather than just in the first two minutes.
However, due to a bug in the old logic, this was happening anyway.