bug#43593: 27.1; `customize-set-variable': wrong prompt for Boolean value

[Eli Zaretskii]

> Date: Thu, 24 Sep 2020 10:09:57 -0700 (PDT)
> From: Drew Adams <drew.adams@oracle.com>
> 
> emacs -Q
> 
> (defcustom bar nil
>   "@@@"
>   :type 'boolean :group 'convenience)
> 
> M-x customize-set-variable bar
> Set variable: bar
> 
> The prompt for the Boolean value is this:
> 
> [boolean] Set customized value for bar to: (y or n)
> 
> Set it to WHAT?

To 'y' or to 'n'.

FWIW, I see no problem here, and would understand immediately what is
meant.  We do this kind of "translation" of boolean values a'll the
time in Customize.  Let's keep in mind that Customize is for users
that aren't Lisp programmers, so we don't want to request them to know
what Lisp boolean data looks like.