Otherwise in e.g. the gnome-ostree integrationtest system, we
end up sending SIGUSR1 to the *entire session*, which triggers
various badness in untested debugging paths from gnome-session.
This test worked when compiled without optimization, but fails with
-O2. Presumably we just happened to find the GMainLoop off the stack
somewhere.
https://bugzilla.gnome.org/show_bug.cgi?id=704267