bug#71429: Inconsistent y-or-n-p prompt behavior in Emacs Lisp

[Stefan Monnier]

> Thanks.  To me, this means that key-valid-p should bind
> search-spaces-regexp to nil, because otherwise the value will subvert
> its contract.  Do you agree?

I kind of agree, but I wonder why it would be non-nil at this point.
AFAIK `search-spaces-regexp` is meant for interactive searches, so
let-binding it around code like `substitute-command-keys`,
`split-string`, or `key-valid-p` sounds like a bug.


        Stefan