response throw ContentNotRenderedError() when render class based view

[speq]

Need to do this before write(response.content)

    # If the response supports deferred rendering, apply template
    # response middleware and the render the response
    if hasattr(response, 'render') and callable(response.render):
        response.render()

    self.write(response.content)

ref: http://groups.google.com/group/django-feincms/browse_thread/thread/dbedd55592966820