Fix SyntaxError

IPython/parallel/controller/dictdb.py

@@ -265,7 +265,7 b' class DictDB(BaseDB):'
 
     def get_history(self):
         """get all msg_ids, ordered by time submitted."""
-        msg_ids = self._records.keys():
+        msg_ids = self._records.keys()
         # Remove any that do not have a submitted timestamp.
         # This is extremely unlikely to happen,
         # but it seems to come up in some tests on VMs.