Trac was/is truly to most awful bug tracking system. I mean a primary function of a bug tracking system should surely be to accept bug reports from users, yet Trac manages to make that the least discoverable and least usable feature. Even things like subscribing to an existing bug report or listing bugs are very hard to find. I would say "impossible" for ordinary people, but will get accused of exaggerating, but go and look at a Trac-based bug tracking system some time to see what I mean. One at random: https://trac.osgeo.org/geos