bug#61535: 29.0.60; choose-completion erases in-region buffer

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Date: Wed, 15 Feb 2023 20:32:18 +0200
> 
> 0. emacs-29 -Q
> 1. type: (with-c C-M-i
> 2. type: M-down ... M-RET
> 3. check that the whole buffer was deleted before a selected
>    completion candidate was inserted to the buffer:
>    C-h v buffer-undo-list RET

Which buffer was deleted? *scratch*?  It isn't here.

And what does "C-h v buffer-undo-list RET" mean?

Bottom line: I don't understand what is the bug here and/or how to
reproduce it.