Fix concatenate

jet/tests/settings.py

@@ -28,7 +28,7 @@ MIDDLEWARE_CLASSES = (
     'django.contrib.messages.middleware.MessageMiddleware',
 )
 
-TEMPLATE_CONTEXT_PROCESSORS = global_settings.TEMPLATE_CONTEXT_PROCESSORS + (
+TEMPLATE_CONTEXT_PROCESSORS = tuple(global_settings.TEMPLATE_CONTEXT_PROCESSORS) + (
     'django.core.context_processors.request',
 )