Just wanted to make a note of how the trac issues with cmucl were fixed, for future reference. These issues showed up in cmucl's git post-receive-hook.
First, the permission on /project/cmucl/trac/log/trac.log was incorrect. It needed to be writable by the group cmucl. I think Erik has fixed this so this won't be a problem in the future (by changing trac's umask to 002).
Second, the trac.db (/project/cmucl/trac/db/trac.db) also needed to be writable by cmucl.
With these changes, trac works beautifully again.
Many thanks to Erik for his help in fixing this.
-- Ray