bug#39564: 28.0.50; read-key function do not display the prompt if called from read-from-minibuffer

[Eli Zaretskii]

> From: Oleh Krehel <ohwoeowho@gmail.com>
> Date: Wed, 12 Feb 2020 14:21:35 +0100
> Cc: 39564@debbugs.gnu.org
> 
> > Thanks, but I still don't understand what should one do with this
> > snippet (after evaluating it) to see the problem.  Please tell more.
> 
> Here's the behavior in 26.3: the minibuffer is 10 lines tall for
> read-from-minibuffer.

Sorry, I still don't understand: are you saying that you get a 10-line
mini-window after just evaluating the code snippet you posted?  If so,
then I cannot reproduce that: I see a 9-line mini-window, both in
Emacs 26.3 and the current emacs-27 branch (Emacs 27.0.60).

Do I need to do anything after evaluating the code you posted?  (I
think I do, because otherwise I don't understand, for example, why you
bind C-f to some function there.)

Thanks.