bug#21396: 25.0.50; read-key's prompt is not visible

[Eli Zaretskii <eliz@gnu.org>]

> From: Tassilo Horn <tsdh@gnu.org>
> Cc: monnier@IRO.UMontreal.CA,  21396@debbugs.gnu.org
> Date: Fri, 04 Sep 2015 10:04:07 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> I'm guilty of having (fset 'yes-or-no-p 'y-or-n-p) in my ~/.emacs,
> >> too, but what does this have to do with this issue?
> >
> > If you don't expect that fset to continue working, nothing.
> 
> I expect that I can alias/fset, add-function :override, or redefine any
> emacs function with a semantically equivalent function.

That's not the expectation I was arguing against.

> Redefining functions is the worst of all customization
> possibilities, of course, but what is the reason that the above
> cannot be expected to continue working?

Supporting this is maintenance burden that we shouldn't be expected to
sustain.  When I'm working on extending a function, how am I supposed
to know that it's defaliased by someone?  If I need to extend the
function to make it incompatible with these tricks, it's a legitimate
development that shouldn't be avoided for fear of breaking someone's
fset.

If people keep using such "customizations", it's a clear sign that
some defcustom or another similar facility is missing, or that the
original code needs improvement.  So when such situations happen,
let's report them to the bug tracker, and let's handle them as we
usually do.