bug#51390: 29.0.50; repeat-mode: Fails to repeat keys in global-map(?)

[Juri Linkov <juri@linkov.net>]

> I'm trying to make next/previous-line repeatable by using the follow
> code snippet,
>
>         (defvar teest
>           (let ((map (make-sparse-keymap)))
>             (define-key map "n" #'next-line)
>             (define-key map "p" #'previous-line)
>             map))
>
> To reproduce the issue,
>
> 1. emacs -Q
> 2. Evaluate the expressions in this message.  Turn on repeat-mode.
> 3. Switch to the *scratch* buffer and press M-<.
> 4. Type C-n.  Notice that it does not trigger the repeat map.
> 5. Type C-p twice.  The repeat map gets triggered in the second keypress
> i.e., when the point is at the first line.

This is because currently only the last character of the initial
key sequence is allowed to be repeated.  The initial key was "C-n"
and the repeat key is "n" - it's not the same key.  This condition
was added to repeat only such key sequences 'C-x u  u u u ...',
but not 'C-/  u u u u ...'.  Now addition of a new option is underway.
It will allow customization of such preference.