Transition from communitheme snap session to ubuntu

[Didier Roche-Tolomelli]

In Bionic, we ship a communitheme snap, which shows up an additional gdm entry named "ubuntu communitheme".

We want those users on Bionic -> Cosmic upgrade (and later, bionic LTS -> f LTS) to fallback to the ubuntu session to not pick the theme in the snap.

However, we still want a way for people to install the communitheme session for testing latest edge.

Plan is:
- remove from ubuntu-session package the communitheme .desktop session files. This way, people will be fallbacked to the ubuntu session.
- readd another session package, like communitheme-session, containing those .desktop files. That will be the package that people can use to use the snap theme version.

[Launchpad Janitor (janitor)]

This bug was fixed in the package gnome-session - 3.30.0-0ubuntu3

---------------
gnome-session (3.30.0-0ubuntu3) cosmic; urgency=medium

  * Introduce a communitheme-snap-session for people who want to test
    the communitheme snap in cosmic and over. Moving them out of the
    ubuntu-session package.
    This split enables us to transition communitheme snap users to default
    ubuntu session after upgrading from bionic to cosmic or next LTS.
    (LP: #1794024)

 -- Didier Roche <email address hidden> Mon, 24 Sep 2018 09:30:46 +0200