bug#56953: Keybinding annotation not displayed in M-x when on button

[Lars Ingebrigtsen]

Stefan Kangas <stefan@marxist.se> writes:

> Steps to reproduce:
>
> 0. emacs -Q
> 1. M-x apropos RET test RET
> 2. C-x o
> 3. n
> 4. M-x apropos-f TAB
>
> In the "*Completions*" buffer, `apropos-follow' is displayed as having
> no keybinding.  If I now press `C-g C-n', and repeat step 4, I correctly
> see that it is bound to RET.

Weird.

M-: (where-is-internal 'apropos-follow)

with point on the button line returns nil, but with point elsewhere, it
returns ([13]).  There isn't any keymap text properties (or overlays)
here, so ... what's going on here?

There's a button there, and apropos-mode-map inherits from
button-buffer-map...  Hm, nope, don't quite understand.