The previous order of removing triggers and their push keys violated a DB constraint.

endpoints/api/trigger.py

@@ -81,10 +81,11 @@ class BuildTrigger(RepositoryParamResource):
                   'service': trigger.service.name, 'config': config_dict},
                  repo=model.get_repository(namespace, repository))
 
+    trigger.delete_instance(recursive=True)
+
     if trigger.write_token is not None:
       trigger.write_token.delete_instance()
 
-    trigger.delete_instance(recursive=True)
     return 'No Content', 204