Sorry if I confused you, but we can't just add tests for this behaviour and add the docs; that's not what I'm suggesting. You need to prove or confirm that this behaviour is a) intended and b) supported, before you can do that. I personally can't confirm that for you, so I'm suggesting you should remove it.

Digging through the source and ping the original implementors to confirm this is going to take a lot of effort, and if you simply noticed this while casually browsing the documentation, I don't think it will be worth the effort.