Trac is an enhanced wiki and issue tracking system for software development projects. It provides a Graphical front end to SVN where diffs in files can be obtained. It cannot update the SVN repository. It simply provides a Project Management interface, wiki, ticketing system, and SVN front end.
This blog's entry made my day: Upgrading my old Berkeley DB svn rep from 4.2 to 4.3 without any hassles. Worked as described (I used the --with-apr option).