Comment 1 for bug 96660

Isn't tigris using Issuezilla, which is a modified version of Bugzilla? For example:
    http://subversion.tigris.org/issues/show_bug.cgi?id=409

Also, I remember Kiko doing some work to make our Bugzilla tracker type work better with Issuezilla instances. The registered OpenOffice tracker is an example of such a tracker.