bug#60886: 29.0.60; split-root-window-below broken for split-window-keep-point

[Eli Zaretskii]

> Date: Thu, 19 Jan 2023 09:49:06 +0100
> Cc: juri@linkov.net, 60886@debbugs.gnu.org
> From: martin rudalics <rudalics@gmx.at>
> 
>  >> What is the "same buffer" when the root window is internal in
>  >> split-root-window-right/-below?
>  >
>  > I guess "the same buffer as the window which was split"?
> 
> In the case sketched above the window which was split had no buffer.

I guess I don't understand the use case then? how can that happen?
And what would you suggest to say in the doc string instead?