bug#47992: [External] : bug#47992: 27; 28; Phase out use of `equal` in `add-hook`, `remove-hook`

[Drew Adams]

> The structural equality does not even perform alpha
> conversion.
> This is probably due to how binding works in Elisp?
> 
> (equal (lambda (x) x) (lambda (y) y))

Right.  Which is, again, why we advise users not to
use lambda forms as hook functions.  But some do,
and if they do they soon learn that if they want to
remove the hook they need to provide a sexp that's
`equal' - a lambda form as an `equal' list.