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

[Alan Mackenzie]

In emacs-29.0.91:

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.

-- 
Alan Mackenzie (Nuremberg, Germany).