FYI: gnome 3.34 session changes seem to break nested compositor (inside gnome)

@guido.gunther I'm on arch and we're in the midst of the big gnome 3.34 update, and it seems changes to gnome-session are breaking the nested compositor setup (true for both x11-nested and wayland-nested).

Running WLR_BACKENDS=x11 phoc/build/run -C phosh/data/rootston.ini -E 'phosh/build/run -U' without setting SKIP_GNOME_SESSION causes immediate termination of the gnome session. Setting this variable causes apps started from the app grid to run in the main gnome session.

It is still possible to start apps inside the nested session from the outside by setting the WAYLAND_DISPLAY variable.

This might be complete noise (arch specific and fixed in gnome update shakeout), but I think it's related to the push to manage the session with systemd --user.