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

[Stefan Kangas]

Severity: minor

This is a bit quirky, but...

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.