Issue Tracking with Bugzilla
If for whatever reason you want to use Trac for its many features but already have Bugzilla deployed for your issue tracking and are unable to move away from Buzilla, this component/plugin should enable you to use trac and have the #123 links automagically link back to your bugzilla installation rather than Trac's own issue tracking pages.
If you have any issues, create a new ticket.
Download the zipped source from here.
Just copy the bugzilla.py file into the 'plugins' sub-folder of your Trac environment.
It is important to make sure you disable Trac's native tickets before the ticket numbers will link to your bugzilla installation correctly. To do this just add 'trac.ticket.*= disabled' to the components section of your trac.ini file. (If there isn't a [components] section, then create one first.)
Out-of-the-box bugzilla.py will try to link to a bugzilla installation running on http://bugzilla. This probably isn't what you want, in order to have it point at your installation add a new section to the trac.ini file named [bugzilla]. The bugzilla plugin understands only one parameter, which is 'bugzilla_url'. Have this point to where your bugzilla installation really resides (trailing slash is optional).
The end of your trac.ini file may now look like:
[components] trac.ticket.*= disabled [bugzilla] bugzilla_url= http://bugzilla