This is what's blowing up the test:

```
ERROR: kitsune.sumo.tests.test_middleware:MobileSwitchTestCase.test_mobile_1
  vi +82  kitsune/sumo/tests/test_middleware.py  # test_mobile_1
    response = self.client.get(u'/en-US/home?mobile=1', follow=True)
  vi +455 vendor/src/django/django/test/client.py  # get
    response = self._handle_redirects(response, **extra)
  vi +579 vendor/src/django/django/test/client.py  # _handle_redirects
    response = self.get(url.path, QueryDict(url.query), follow=False, **extra)
  vi +453 vendor/src/django/django/test/client.py  # get
    response = super(Client, self).get(path, data=data, **extra)
  vi +279 vendor/src/django/django/test/client.py  # get
    return self.request(**r)
  vi +406 vendor/src/django/django/test/client.py  # request
    response = self.handler(environ)
  vi +111 vendor/src/django/django/test/client.py  # __call__
    response = self.get_response(request)
  vi +178 vendor/src/django/django/core/handlers/base.py  # get_response
    response = self.handle_uncaught_exception(request, resolver, sys.exc_info())
  vi +115 vendor/src/django/django/core/handlers/base.py  # get_response
    response = callback(request, *callback_args, **callback_kwargs)
  vi +23  vendor/src/django-mobility/mobility/decorators.py  # wrapper
    return f(request, *args, **kw)
  vi +17  kitsune/products/views.py  # product_list
    'products': products})
  vi +53  vendor/src/django/django/shortcuts/__init__.py  # render
    return HttpResponse(loader.render_to_string(*args, **kwargs),
  vi +177 vendor/src/django/django/template/loader.py  # render_to_string
    return t.render(context_instance)
  vi +193 vendor/src/jingo/jingo/__init__.py  # render
    return super(Template, self).render(context_dict)
  vi +49  vendor/src/test-utils/test_utils/__init__.py  # instrumented_render
    return old_render(self, *args, **kwargs)
  vi +891 /Users/rlr/.virtualenvs/kitsune/lib/python2.7/site-packages/jinja2/environment.py  # render
    return self.environment.handle_exception(exc_info, True)
  vi +5   kitsune/products/templates/products/mobile/products.html  # top-level template code
    {% set styles = ('mobile/products',) %}
  vi +36  kitsune/sumo/templates/mobile/base.html  # top-level template code
    {% block head %}
  vi +24  kitsune/products/templates/products/mobile/products.html  # block "head"
    background-image: url({{ products[0].sprite_url(retina=False) }});
  vi +371 /Users/rlr/.virtualenvs/kitsune/lib/python2.7/site-packages/jinja2/environment.py  # getattr
    return getattr(obj, attribute)
UndefinedError: caching.base.CachingQuerySet object has no element 0
```