Exception in Atom feed view

[joar]

Trying to access any Atom feed (e.g.
`http://mg.wandborg.se/u/joar/atom/ <http://mg.wandborg.se/u/joar/atom/>`_)
will raise an exception.

::

    ------------------------------------------------------------
    Error - <type 'exceptions.AttributeError'>: 'BaseResponse' object has no attribute 'vary'
    URL: http://mg.wandborg.se/u/joar/atom/
    File '/home/joar/mediagoblin/lib/python2.7/site-packages/Paste-1.7.5.1-py2.7.egg/paste/exceptions/errormiddleware.py', line 144 in __call__
      app_iter = self.application(environ, sr_checker)
    File '/home/joar/mediagoblin/lib/python2.7/site-packages/Paste-1.7.5.1-py2.7.egg/paste/urlmap.py', line 203 in __call__
      return app(environ, start_response)
    File '/home/joar/mediagoblin/lib/python2.7/site-packages/Beaker-1.6.1-py2.7.egg/beaker/middleware.py', line 155 in __call__
      return self.wrap_app(environ, session_start_response)
    File '/home/joar/mediagoblin/mediagoblin/app.py', line 175 in __call__
      m.process_response(request, response)
    File '/home/joar/mediagoblin/mediagoblin/middleware/csrf.py', line 101 in process_response
      response.vary = (response.vary or []) + ['Cookie']
    AttributeError: 'BaseResponse' object has no attribute 'vary'

[nyergler]

This is a duplicate of `#653 </issues/653>`_, resolved in merge
request 30.

[Christopher Allan Webber]

Since I made the merge for `#643 </issues/643>`_, this is fixed
also.

[Will Kahn-Greene]

The original url for this bug was ​http://bugs.foocorp.net/issues/648 .