Allow using CACHE_BACKEND as an alias to CELERY_CACHE_BACKEND

celery/conf.py

@@ -117,7 +117,7 @@ ALWAYS_EAGER = _get("CELERY_ALWAYS_EAGER")
 EAGER_PROPAGATES_EXCEPTIONS = _get("CELERY_EAGER_PROPAGATES_EXCEPTIONS")
 RESULT_BACKEND = _get("CELERY_RESULT_BACKEND", compat=["CELERY_BACKEND"])
 CELERY_BACKEND = RESULT_BACKEND # FIXME Remove in 1.4
-CACHE_BACKEND = _get("CELERY_CACHE_BACKEND")
+CACHE_BACKEND = _get("CELERY_CACHE_BACKEND") or _get("CACHE_BACKEND")
 CACHE_BACKEND_OPTIONS = _get("CELERY_CACHE_BACKEND_OPTIONS") or {}
 TASK_SERIALIZER = _get("CELERY_TASK_SERIALIZER")
 TASK_RESULT_EXPIRES = _get("CELERY_TASK_RESULT_EXPIRES")