bug#67226: 30.0.50; Regression in previous-complete-history-element with empty input

[Stefan Monnier]

> The regression is on this line in `previous-matching-history-element`:
>
>   (string-match (concat ".*\\(" regexp "\\)") match-string)
>
> In GNU Emacs 29.1.90
>
>   (string-match ".*\\(^\\)" "foo")
>   => 0
>
> But in GNU Emacs 30.0.50
>
>   (string-match ".*\\(^\\)" "foo")
>   => nil
>
> Cc:ing Stefan.

Thanks, I believe this is now fixed on `master`.


        Stefan