In Ubuntu, it appeared like we needed a britney hint. I thought we did
in previous Debian transitions too but I don't see it in the list of
hints. Maybe this list isn't needed then:
hint gnome-shell/48~beta-4 mutter/48~beta-7 gnome-kiosk/48~alpha-2 gnome-remote-desktop/48~alpha-2
gnome-shell-extension-tiling-assistant/51-1
gnome-shell-extensions/48~rc-1