AttributeError: 'ICal20Feed' object has no attribute 'content_type'

[froi]

https://sentry.io/app23049962herokucom/production/issues/281139256/

AttributeError: 'ICal20Feed' object has no attribute 'content_type'
(1 additional frame(s) were not displayed)
...
  File "django/core/handlers/base.py", line 249, in _legacy_get_response
    response = self._get_response(request)
  File "django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "newrelic/hooks/framework_django.py", line 492, in wrapper
    return wrapped(*args, **kwargs)
  File "django/contrib/syndication/views.py", line 42, in __call__
    response = HttpResponse(content_type=feedgen.content_type)

AttributeError: 'ICal20Feed' object has no attribute 'content_type'

[jpadilla]

Fixed via 42f843c70e66bb62ba51758843a9d1210866d29d