Fixed #22362 -- Improved AuthenticationMiddleware assertion message.

class AuthenticationMiddleware(object):

    def process_request(self, request):

        assert hasattr(request, 'session'), "The Django authentication middleware requires session middleware to be installed. Edit your MIDDLEWARE_CLASSES setting to insert 'django.contrib.sessions.middleware.SessionMiddleware'."

        assert hasattr(request, 'session'), (

            "The Django authentication middleware requires session middleware "

            "to be installed. Edit your MIDDLEWARE_CLASSES setting to insert "

            "'django.contrib.sessions.middleware.SessionMiddleware' before "

            "'django.contrib.auth.middleware.AuthenticationMiddleware'."

        )

        request.user = SimpleLazyObject(lambda: get_user(request))