get_success_url should redirect to postman_inbox when _get_referrer is the same as request url

[Former user]

ComposeMixin.get_success_url should check if _get_referrer(request) is the same as request.path. If so redirect to postman_inbox instead of looping back to _get_referrer(request)

[Patrick Samson]

'postman_inbox' is not a target, but the last resort fallback to the redirection, if everything else is missing. Generally, in the templates, you should use the query string parameter 'next=' to keep control of the workflow. Refer to the built-in templates of the app to see that design.