As nirik mentioned in IRC, trying to view #89 gives a traceback, possibly due to a bug in the Git plugin (a similar traceback happens on the WikiFormatting page). Other people have experienced the same problem, and there has been a ticket sitting at http://trac-hacks.org/ticket/1721 for the past two months.

If anybody knows Python/Trac well, perhaps we can try to trace this bug a bit further. If this is useful, trying to use the Storage class from /usr/lib/python2.4/site-packages/gitplugin/PyGIT.py in a Python shell seems to work as expected.