fix(tests): fix CACHE_BACKEND test for Django 1.2

The format for the CACHE_BACKEND Django setting was changed in Django
1.3+ to the new dictionary-based CACHES style (which used to be a single
string-based setting i.e. scheme://). This fix simply updates the
CACHE_BACKEND setting in the test so it operates as expected for Django
1.2.

Author: zpencerq

djcelery/tests/test_backends/test_cache.py

@@ -5,6 +5,7 @@
 from datetime import timedelta
 
 from billiard.einfo import ExceptionInfo
+import django
 from django.core.cache.backends.base import InvalidCacheBackendError
 
 from celery import result
@@ -103,8 +104,13 @@ def test_custom_cache_backend(self):
         from celery import current_app
         prev_backend = current_app.conf.CELERY_CACHE_BACKEND
         prev_module = sys.modules['djcelery.backends.cache']
-        current_app.conf.CELERY_CACHE_BACKEND = \
-            'django.core.cache.backends.dummy.DummyCache'
+
+        if django.VERSION >= (1, 3):
+            current_app.conf.CELERY_CACHE_BACKEND = \
+                'django.core.cache.backends.dummy.DummyCache'
+        else:
+            # Django 1.2 used 'scheme://' style cache backends
+            current_app.conf.CELERY_CACHE_BACKEND = 'dummy://'
         sys.modules.pop('djcelery.backends.cache')
         try:
             from djcelery.backends.cache import cache