gunicorn serving Trac traceback

(trac)[jsmits@imac:~/.virtualenvs/trac]$ gunicorn --workers=1 wsgi:app
2010-03-20 13:03:37 [88765] [INFO] Arbiter booted
2010-03-20 13:03:37 [88765] [INFO] Listening at: http://127.0.0.1:8000
2010-03-20 13:03:37 [88766] [INFO] Worker spawned (pid: 88766)
2010-03-20 13:04:02 [88766] [ERROR] Error processing request.
Traceback (most recent call last):
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/gunicorn/worker.py", line 153, in handle
    response = self.app(req.read(), req.start_response)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/main.py", line 420, in dispatch_request
    return _dispatch_request(req, env, env_error)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/main.py", line 528, in _dispatch_request
    req.send_error(exc_info, status=500, env=env, data=data)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/api.py", line 395, in send_error
    exc_info)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/main.py", line 450, in _dispatch_request
    dispatcher.dispatch(req)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/main.py", line 230, in dispatch
    req.send(output, content_type or 'text/html')
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/api.py", line 358, in send
    self.write(content)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/api.py", line 459, in write
    self.end_headers()
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/api.py", line 265, in end_headers
    self._write = self._start_response(self._status, self._outheaders)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/gunicorn/http/request.py", line 164, in start_response
    raise AssertionError("Response headers already set!")
AssertionError: Response headers already set!
2010-03-20 13:04:03 [88766] [ERROR] Error processing request.
Traceback (most recent call last):
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/gunicorn/worker.py", line 153, in handle
    response = self.app(req.read(), req.start_response)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/main.py", line 420, in dispatch_request
    return _dispatch_request(req, env, env_error)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/main.py", line 483, in _dispatch_request
    req.send_error(sys.exc_info(), status=e.code, env=env, data=data)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/api.py", line 398, in send_error
    self.write(data)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/api.py", line 459, in write
    self.end_headers()
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/trac/web/api.py", line 265, in end_headers
    self._write = self._start_response(self._status, self._outheaders)
  File "/Users/jsmits/.virtualenvs/trac/lib/python2.6/site-packages/gunicorn/http/request.py", line 164, in start_response
    raise AssertionError("Response headers already set!")
AssertionError: Response headers already set!