corrections for mongodb

Author: Johannes Otepka

ipyparallel/tests/test_label.py

@@ -65,7 +65,7 @@ def run_tasks(self, view):
 
     def check_labels(self, labels):
         # query database
-        data = self.rc.db_query({'label': {"$nin": ""}}, keys=['msg_id', 'label'])
+        data = self.rc.db_query({'label': {"$nin": [""]}}, keys=['msg_id', 'label'])
         for d in data:
             msg_id = d['msg_id']
             label = d['label']