bug#51173: 28.0.60; gnus-article-describe-key doesn't work

[Lars Ingebrigtsen <larsi@gnus.org>]

Katsumi Yamaoka <yamaoka@jpl.org> writes:

> The following example program returns `sh-case' on Emacs 27 and
> olders, however to make it work on Emacs 28 and 29 the third
> line has to be uncommented.  So does `describe-key' case.
>
> (with-temp-buffer
>   (sh-mode)
>   ;;(set-window-buffer nil (current-buffer))
>   (describe-key-briefly "\C-c\C-c"))
>
> I don't know when/why those commands were changed to require the
> buffer (where the keymap is) to be visited in the selected window,
> but now `gnus-article-describe-key\(-briefly\)?' doesn't work
> because of this.  A patch to gnus-art.el is attached, though the
> one that should be fixed might be help.el.

I think this sounds like a bug in describe-key*, so perhaps it should be
fixed there?  Looking at the history, I'm not at all sure what caused
this regression, but perhaps it's:

commit 9d4af3e6bdfac374f6c9591566c010e6a1514751
Author:     Stefan Monnier <monnier@iro.umontreal.ca>
AuthorDate: Tue Jan 30 11:57:40 2018 -0500

I've added Stefan to the CCs.

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(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no