CVSTrac
The TracHistory states that CVSTrac was the original source of inspiration for Trac.
Indeed, CVSTrac was certainly the first system to integrate browsing of a VersioningSystemBackend (originally CVS), a bug tracking system and a Wiki.
CVSTrac was created by D. Richard Hipp, who is also the author of the embeddable SQL database, SQLite.
See CVSTrac in action for SQLite and for CvsTrac itself.
While CVSTrac is still live, a new generation of this software, called Fossil is available. See for example the Timeline. The nice thing here is that this CVSTrac / Trac clone is not only using a distributed version control system, it is a DVCS. Interesting stuff for #1465.