bug#64062: Emacs 29.0.91: With enable-recursive-minibuffers, C-x b foo splits the window.

[Gregory Heytings]

> emacs -Q
> M-: (setq enable-recursive-minibuffers t)
> M-x
> C-x b foo
>
> This creates the buffer foo, but erroneously splits the displayed window 
> and displays the new buffer in the right hand or bottom half of the 
> frame (depending on the frame's geometry).
>
> The window should not be split, and the new buffer should occupy the 
> entirety of the original window.

AFAICS, that's not a bug.  Emacs 25, 26, 27 and 28 behave the same 
(switch-to-buffer calls pop-to-buffer), and it makes sense to leave, by 
default, the buffer in which M-x was called visible.  You can customize 
that behavior with display-buffer-base-action.