Subject: bug#35497: [PATCH] Don't rewrite buffer contents after saving by rename

From: Eli Zaretskii <[email-masked]>
Date: Wed, 01 May 2019 22:54:49 +0300

> From: Jonathan Tomer <[email-masked]>
> Date: Wed, 1 May 2019 12:29:42 -0700
> Cc: Michael Albinus <[email-masked]>, [email-masked]
> 
> It's true that notifications are imperfect, but IMO they are the only possible way to test that particular invariant,

I'm not sure.  You could instead advise or hook write-region, and see
that it is not being called to write to the file, for example.
Wouldn't that be easier and more reliable?