bug#65577: 29.1; set <signal> <usr1> in global map

[Eli Zaretskii <eliz@gnu.org>]

> From: Shynur Xie <one.last.kiss@outlook.com>
> Date: Mon, 28 Aug 2023 07:29:20 +0000
> msip_labels: 
> 
> This report is about the question asked at
> <https://lists.gnu.org/archive/html/help-gnu-emacs/2023-08/msg00462.html>.
> 
> Reproduce (-Q):
> 
>     (keymap-global-set "<signal> <usr1>"
>       (lambda ()  ; doesn't work.
>         (interactive)
>         (message "teeest: signal usr1")))
>     (signal-process (emacs-pid) 'sigusr1)
>     (keymap-set special-event-map "<sigusr1>"
>       (lambda ()  ; does work
>         (interactive)
>         (message "teeest: sigusr1")))
> 
> Is this a documentation bug?  Or am I missing something?

Stefan, it sounds like the first example is some left-over from old
handling of signals?  I don't see a "function key" named 'signal'
bound anywhere in the global map.  So the 1st example above should
only work if 'signal' is a prefix key bound in the global-map, right?

  (keymap-lookup global-map "<f1>")
    => help-command

but

  (keymap-lookup global-map "<signal>")
    => nil