Authentication error with Standalone ArcGIS Server services.

[Yogesh_Chavan]

We are hitting the exact same error with ArcGIS Server 11.3(Standalone). 

https://github.com/Esri/arcgis-python-api/issues/752

Is this something re-triggered, or is not yet fixed?

The error is only reproducible for the services in folders, for services in root, the issue is not reproducible.

This same works if using the services in root:

Any help on this would be highly appreciated.