bug#60066: 30.0.50; whitespace-mode modifies buffer

[Eli Zaretskii]

> From: Bastian Beranek <bastian.beischer@gmail.com>
> Date: Wed, 14 Dec 2022 17:53:54 +0100
> Cc: Richard Hansen <rhansen@rhansen.org>, 60066@debbugs.gnu.org
> 
> It might be worth pointing out that there are no actual differences
> between the buffer and its on-disk counterpart, but still emacs
> considers the buffer to be modified, as if a change was made and
> reverted (but not through undo).

That's most probably because whitespace.el puts text properties on
some buffer text.