Subject: bug#77942: 31.0.50; replace-region-contents gets stuck

From: Eli Zaretskii <[email-masked]>
Date: Tue, 22 Apr 2025 14:37:13 +0300

> Cc: Paul Eggert <[email-masked]>, [email-masked]
> From: Gerd Möllmann <[email-masked]>
> Date: Tue, 22 Apr 2025 05:48:14 +0200
> 
> But honestly, what the heck? Does someone know what this diffing is
> about in the first place?

It's about leaving the unchanged portions of text intact, including
their properties, overlays, markers, etc.  I believe the doc string
says that much.