Error message implies subset; was triggered by superset, too

src/calng/CalibrationManager.py

@@ -1198,7 +1198,7 @@ class CalibrationManager(DeviceClientBase, Device):
         all_req_servers = set(server_by_group.values()).union(
             server_by_layer.values())
 
-        if all_req_servers != up_servers:
+        if set(all_req_servers) < set(up_servers):
             return self._set_error('One or more device servers are not '
                                    'listed in the device servers '
                                    'configuration')