Description of problem: The GNOME upstream is migrating their bug filing instance to gitlab.gnome.org. So the logic to specify external bug for GNOME in this bugzilla instance needs migration too. Ref: https://mail.gnome.org/archives/desktop-devel-list/2018-March/msg00023.html
I renamed the current tracker to GNOME Bugzilla and created a new tracker name GNOME Gitlab.