bug#60015: 29.0.60; multi-line messages truncated in non-selected minibuffer

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Date: Mon, 12 Dec 2022 20:03:41 +0200
> 
> 0. emacs -Q
> 1. (run-with-timer 5 5 'message "abc\ndef")
> 2. then activate the minibuffer and switch back to the original buffer
> 3. after some time observe that only the first line of the multi-line message
>    is displayed in the minibuffer

Doesn't happen here (I waited for 2.5 minutes).  Is the recipe
complete and exact?  Does it perhaps matter how do you "switch back to
the original buffer"?  (I used a mouse click.)

When the problem happens, what do you see in *Messages*?  Anything
other that "abc\ndef"?