setting THEME_NAME to None when it's set to an empty string

lms/envs/aws.py

@@ -163,6 +163,11 @@ BULK_EMAIL_ROUTING_KEY = HIGH_PRIORITY_QUEUE
 
 # Theme overrides
 THEME_NAME = ENV_TOKENS.get('THEME_NAME', None)
+# Workaround for setting THEME_NAME to an empty
+# string which is the default due to this ansible
+# bug: https://github.com/ansible/ansible/issues/4812
+if THEME_NAME == "":
+    THEME_NAME = None
 if not THEME_NAME is None:
     enable_theme(THEME_NAME)
     FAVICON_PATH = 'themes/%s/images/favicon.ico' % THEME_NAME