If you think this really should work and you can reproduce it. Then you should consider to report this problem to the Trac team.
Go to http://trac.edgewall.com/ and create a new ticket where you describe the problem, how to reproduce it. Don't forget to include the python traceback found below.
TracGuide — The Trac User and Administration Guide
Traceback (most recent call last): File "/home2/fumanchu/lib/python2.4/trac/web/cgi_frontend.py", line 130, in run dispatch_request(req.path_info, req, env) File "/home2/fumanchu/lib/python2.4/trac/web/main.py", line 139, in dispatch_request dispatcher.dispatch(req) File "/home2/fumanchu/lib/python2.4/trac/web/main.py", line 107, in dispatch resp = chosen_handler.process_request(req) File "/home2/fumanchu/lib/python2.4/trac/wiki/web_ui.py", line 114, in process_request req.write(page.text) File "/home2/fumanchu/lib/python2.4/trac/web/cgi_frontend.py", line 69, in write return self.__output.write(data) TypeError: argument 1 must be string or read-only character buffer, not None