Using the bus name to notify service startup to systemd has some
disadvantages. The main one being that systemd will consider a
gnome-shell restart (Alt+F2 r) a service failure and restart the shell,
cleaning up all its children (i.e. user launched applications). In the
future the shell should launch applications in their own transient unit
so that a service restart does not affect applications.
Another potential issue is that we must never load
gnome-shell-wayland.service and gnome-shell-x11.service at the same
time, as systemd does not like two services providing the same bus
name.
Fixes https://gitlab.gnome.org/GNOME/gnome-shell/issues/1496https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/690