pantheon.elementary-terminal: Fix unbreakable loop when closing terminal

[bobby285271]

Description of changes

I would appreciate some review (if any) before I commit this to gnome, this should fixes the issue I mentioned in https://github.com/NixOS/nixpkgs/pull/192174#issuecomment-1257011432 but the issue is really weird to be fix here, just like the patch I made for e-calendar.

How to merge

If no force push happens on gnome we can just change the merge base and merge. Otherwise we cherry-pick it to gnome manually

[bobby285271]

@ofborg test pantheon

[bobby285271]

Ugh, I decided the merge base is not important, I expect the patch to work in both GLib 2.72 and 2.74