Tengo la siguiente vista simple. ¿Por qué está dando lugar a este error?

The view auth_lifecycle.views.user_profile didn't return an HttpResponse object. It returned None instead.

"""Renders web pages for the user-authentication-lifecycle project."""
from django.shortcuts               import render
from django.template                import RequestContext
from django.contrib.auth            import authenticate, login

def user_profile(request):
    """Displays information unique to the logged-in user."""

    user = authenticate(username='superuserusername', password='sueruserpassword')
    login(request, user)

    render(request, 'auth_lifecycle/user_profile.html',
           context_instance=RequestContext(request))