Only create loc_cache CACHE entry if it doesn't exist in ENV_TOKENS config.

cms/envs/aws.py

@@ -124,10 +124,11 @@ LOG_DIR = ENV_TOKENS['LOG_DIR']
 CACHES = ENV_TOKENS['CACHES']
 # Cache used for location mapping -- called many times with the same key/value
 # in a given request.
-CACHES['loc_cache'] = {
+if 'loc_cache' not in CACHES:
+    CACHES['loc_cache'] = {
         'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
         'LOCATION': 'edx_location_mem_cache',
-}
+    }
 
 SESSION_COOKIE_DOMAIN = ENV_TOKENS.get('SESSION_COOKIE_DOMAIN')
 SESSION_ENGINE = ENV_TOKENS.get('SESSION_ENGINE', SESSION_ENGINE)

lms/envs/aws.py

@@ -157,10 +157,11 @@ LOG_DIR = ENV_TOKENS['LOG_DIR']
 CACHES = ENV_TOKENS['CACHES']
 # Cache used for location mapping -- called many times with the same key/value
 # in a given request.
-CACHES['loc_cache'] = {
+if 'loc_cache' not in CACHES:
+    CACHES['loc_cache'] = {
         'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
         'LOCATION': 'edx_location_mem_cache',
-}
+    }
 
 # Email overrides
 DEFAULT_FROM_EMAIL = ENV_TOKENS.get('DEFAULT_FROM_EMAIL', DEFAULT_FROM_EMAIL)