bug#68022: 30.0.50; File cache completions accumulate instead of replacing minibuffer input

[Eli Zaretskii <eliz@gnu.org>]

> From: Eshel Yaron <me@eshelyaron.com>
> Cc: 68022@debbugs.gnu.org
> Date: Mon, 25 Dec 2023 16:41:27 +0100
> 
> Instead of using `file-cache-add-directory-using-find`, you can also set
> `file-cache-alist` directly:
> 
> --8<---------------cut here---------------start------------->8---
> (setq file-cache-alist
>       '(("bar" "/foo")
>         ("baz" "/foo")
>         ("bad" "/foo")
>         ("bay" "/foo")
>         ("ban" "/foo")))
> --8<---------------cut here---------------end--------------->8---
> 
> Then `C-x C-f ba C-TAB M-<down> M-<down> ...` should show the issue.
> 
> Earlier I wrote that the same issue appears in Emacs 29.1, but now I
> tested that again and I think I might have been mistaken.  In Emacs 29.1
> I see a different issue: `M-<down>` in the above recipe emits an error:
> 
> --8<---------------cut here---------------start------------->8---
> Wrong type argument: number-or-marker-p, ""
> --8<---------------cut here---------------end--------------->8---
> 
> and doesn't change the minibuffer contents.

That's what I see in Emacs 29.  So are we talking about one problem or
two different problems?