When we update the main monitor, there is a rule that makes it so that
popup windows use the same main monitor as their parent. In the commit
f4d07caa38e51d09ee73bab20334a6b5c28952d6 the call that updates and
fetches the main monitor of the toplevel accidentally changed to update
from itself, causing a indefinite recursion eventually resulting in a
crash.
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/279
e191c21e04