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

[Stefan Monnier <monnier@IRO.UMontreal.CA>]

>   1. emacs -Q
>   2. eval (read-key "Gimme Key: ") in *scratch*
> the key will be read but the prompt is not shown in the minibuffer
[...]
> commit 5dc644a6b01e2cf950ff617ab15be4bf1917c38c
> Author: Stefan Monnier <monnier@iro.umontreal.ca>
> Date:   Tue Sep 1 21:14:18 2015 -0400
>     Generalize the prefix-command machinery of C-u

Hmm... I'll look into it.

> Git bisect says the commit introducing this problem is Stefan whom I
> added to the Cc.

Thanks for bisecting.  Putting me in the Cc was more trouble than
anything else: it means I get *your* message instead of the one from
Debbugs, so I don't get to know the bug-number and a naive reply would
end up creating a new bug-nb!
[ Tho, IIRC Glenn(?) added some Message-ID matching to Debbugs to try
  and catch those cases.  So maybe it's not that bad.  ]

Better either not put the person in the Cc (in case you expect/know the
person subscribes to bug-gnu-emacs), or else use "X-Debbugs-Cc:" which
instructs Debbugs to add the person to the Cc of the messages it sends out.

Yes, it's an annoying subtlety,


        Stefan