Trying to enter a ticket from qutecom trac into the "See Also" field of bug 361181 will result in the following error message: "http://trac.qutecom.org/ticket/287 is not a valid URL to a bug." Please allow entering trac tickets into this field.
CC'ing upstream here as I think its an upstream bug.
Bugzilla 4.1.1 supports Trac, see http://mxr.mozilla.org/mozilla/source/webtools/bugzilla/Bugzilla/BugUrl/. In 4.0, things work a bit differently, and you have to add code for Trac in the add_see_also subroutine.
Quote from the Bugzilla 4.2 ChangeLog: Bugs: The See Also field now accepts URLs pointing to MantisBT, Trac, JIRA and the sourceforge.net bug trackers.