Forbidden exception being incorrectly instantiated by filesystem driver

Stack trace:

  File "/usr/lib/python2.7/site-packages/eventlet/wsgi.py", line 442, in handle_one_response
    result = self.application(self.environ, start_response)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 130, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/glance/common/wsgi.py", line 486, in __call__
    response = req.get_response(self.application)
  File "/usr/lib/python2.7/site-packages/webob/request.py", line 1296, in send
    application, catch_exc_info=False)
  File "/usr/lib/python2.7/site-packages/webob/request.py", line 1260, in call_application
    app_iter = application(self.environ, start_response)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 130, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/osprofiler/web.py", line 99, in __call__
    return request.get_response(self.application)
  File "/usr/lib/python2.7/site-packages/webob/request.py", line 1296, in send
    application, catch_exc_info=False)
  File "/usr/lib/python2.7/site-packages/webob/request.py", line 1260, in call_application
    app_iter = application(self.environ, start_response)
  File "/usr/lib/python2.7/site-packages/keystonemiddleware/auth_token/__init__.py", line 634, in __call__
    return self._call_app(env, start_response)
  File "/usr/lib/python2.7/site-packages/keystonemiddleware/auth_token/__init__.py", line 554, in _call_app
    return self._app(env, _fake_start_response)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 130, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/glance/common/wsgi.py", line 486, in __call__
    response = req.get_response(self.application)
  File "/usr/lib/python2.7/site-packages/webob/request.py", line 1296, in send
    application, catch_exc_info=False)
  File "/usr/lib/python2.7/site-packages/webob/request.py", line 1260, in call_application
    app_iter = application(self.environ, start_response)
  File "/usr/lib/python2.7/site-packages/paste/urlmap.py", line 203, in __call__
    return app(environ, start_response)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 144, in __call__
    return resp(environ, start_response)
  File "/usr/lib/python2.7/site-packages/routes/middleware.py", line 131, in __call__
    response = self.app(environ, start_response)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 144, in __call__
    return resp(environ, start_response)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 130, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/usr/lib/python2.7/site-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/glance/common/wsgi.py", line 777, in __call__
    request, **action_args)
  File "/usr/lib/python2.7/site-packages/glance/common/wsgi.py", line 801, in dispatch
    return method(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/glance/common/utils.py", line 509, in wrapped
    return func(self, req, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/glance/api/v1/images.py", line 1089, in delete
    {'status': ori_status})
  File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 85, in __exit__
    six.reraise(self.type_, self.value, self.tb)
  File "/usr/lib/python2.7/site-packages/glance/api/v1/images.py", line 1085, in delete
    upload_utils.initiate_deletion(req, loc_data, id)
  File "/usr/lib/python2.7/site-packages/glance/api/v1/upload_utils.py", line 46, in initiate_deletion
    id, location_data)
  File "/usr/lib/python2.7/site-packages/glance/common/store_utils.py", line 124, in delete_image_location_from_backend
    safe_delete_from_backend(context, image_id, location)
  File "/usr/lib/python2.7/site-packages/glance/common/store_utils.py", line 58, in safe_delete_from_backend
    ret = store_api.delete_from_backend(location['url'], context=context)
  File "/usr/lib/python2.7/site-packages/glance_store/backend.py", line 290, in delete_from_backend
    return store.delete(loc, context=context)
  File "/usr/lib/python2.7/site-packages/glance_store/capabilities.py", line 226, in op_checker
    return store_op_fun(store, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/glance_store/_drivers/filesystem.py", line 492, in delete
    raise exceptions.Forbidden(_("You cannot delete file %s") % fn)
TypeError: __init__() takes exactly 1 argument (2 given)

glance_store/_drivers/filesystem.py's delete method raises an exception if deletion of an image fails:

     def delete(self, location, context=None):
        """
        Takes a `glance_store.location.Location` object that indicates
        where to find the image file to delete

        :location `glance_store.location.Location` object, supplied
                  from glance_store.location.get_location_from_uri()

        :raises NotFound if image does not exist
        :raises Forbidden if cannot delete because of permissions
        """
        loc = location.store_location
        fn = loc.path
        if os.path.exists(fn):
            try:
                LOG.debug(_("Deleting image at %(fn)s"), {'fn': fn})
                os.unlink(fn)
            except OSError:
                raise exceptions.Forbidden(_("You cannot delete file %s") % fn)
        else:
            raise exceptions.NotFound(image=fn)

The problem is that the instantiation of exceptions.Forbidden is passing an argument when it shouldn't be:

class Forbidden(GlanceStoreException):
    message = _("You are not authorized to complete this action.")

class GlanceStoreException(Exception):
    """
    Base Glance Store Exception

    To correctly use this class, inherit from it and define
    a 'message' property. That message will get printf'd
    with the keyword arguments provided to the constructor.
    """
    message = ''

    def __init__(self, **kwargs):
        self.msg = kwargs.pop('message', None) or self.message % kwargs
        super(Exception, self).__init__(self.msg)

If the instantiation within filesystem.py is changed to:

raise exceptions.Forbidden(message=(_("You cannot delete file %s") % fn))

then the exception is thrown as expected:

  ...
  File "/usr/lib/python2.7/site-packages/glance_store/_drivers/filesystem.py", line 492, in delete
    raise exceptions.Forbidden(message=(_("You cannot delete file %s") % fn))
Forbidden: You cannot delete file /var/lib/glance/images/47dfa80f-cc9e-4f18-ab1b-96f4204d228a