Tigris.org hosts a number of free software projects. Their bugtracker URL format is: http://rapidsvn.tigris.org/issues/show_bug.cgi?id=XXX
Should be pushed to production database shortly.
Actually, I'm sorry, that URL was specific to the RapidSVN project. My bad. There doesn't seem to be a generic URL for Tigris.org projects; each project has its own bugtracker URL which is a shame. That said, I'd be happy if you left this reference in, but name it "RapidSVN" rather than "Tigris.org". Sorry for the bad info there.
Changed to RapidSVN.