Adapted to cleanup of do_unpacking

goes together with LHCb!4574 (merged)

Hlt/Hlt2Conf/options/hlt2_check_output.py

@@ -74,7 +74,7 @@ cppyy.gbl.DataSvcHelpers.RegistryEntry.__bool__ = lambda x: True
 # The test can't check anything if no event fired
 found_events = False
 found_child_relations = False
-while TES['/Event']:
+while TES["/Event/Hlt2/DecReports"]:
     print('Checking next event.')
 
     #TES.dump()