UC20 system fails to seed when model contains snaps requiring experimental.user-daemons or dbus-activation

[James Henstridge]

I encountered this using the image included in the artifact of this build:

https://github.com/canonical/ubuntu-core-desktop/actions/runs/393663991

In short, we have:

1. a gadget snap that turns on experimental.user-daemons and experimental.dbus-activation via defaults.
2. an ubuntu-desktop-session snap that includes a dbus activatable session daemon (requiring both).
3. a model definition requiring both of these snaps.

When booting the image, it does not seed correctly with snapd logging the following warning:

    seeding failed with: experimental feature disabled - test it by setting 'experimental.user-daemons' to true. This indicates an error in your distribution, please see https://forum.snapcraft.io/t/16341 for more information.

No snaps are mounted under /snap at this point. @mvo grabbed this snapd state file from a boot of the image, showing a bunch of tasks with no changes registered:

https://paste.ubuntu.com/p/yRr5hCqyXF/

[Samuele Pedroni (pedronis)]

I'm actively working to fix this

[Samuele Pedroni (pedronis)]

will be in 2.50