Update Process reports completion before it is actually done

I am updating  PMM 2.0.0 to 2.0.1 

I see dialog "Update Completed" appears very quickly but actual software is not updated. As I refresh it promptly I can see the old interface, when if I'm unlucky I can have page failing to load (assuming when components in questions are actually updated) until I finally see new interface.

By behavior it seems what "Update Completed" is displayed way before update is actually completed and update really runs in background.