Subject: Re: bug#58992: 28.2; "lax space matching" no longer works

From: Eli Zaretskii <[email-masked]>
Date: Thu, 03 Nov 2022 20:18:57 +0200

> Date: Thu, 03 Nov 2022 18:11:43 +0000
> From: Gregory Heytings <[email-masked]>
> cc: Eli Zaretskii <[email-masked]>, [email-masked]
> 
> emacs -Q
> ab RET cd RET ab SPC cd
> M-<
> C-s b SPC c ;; only one match
> C-x C-s foo RET
> M-<
> C-s b SPC c ;; two matches in Emacs 27, one match in Emacs 28
> 
> Hmm...

Did you look at the value of search-whitespace-regexp in both cases?