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

[Eli Zaretskii]

> From: Jonathan Tomer <jktomer@google.com>
> Date: Wed, 1 May 2019 12:29:42 -0700
> Cc: Michael Albinus <michael.albinus@gmx.de>, 35497@debbugs.gnu.org
> 
> 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?