bug#23904: Btrfs clone support in copy operations

[Eli Zaretskii]

> Cc: dmantipov@yandex.ru, 23904@debbugs.gnu.org, sbaugh@catern.com,
>  kieran@kcolford.com
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Sun, 11 Sep 2016 10:17:17 -0700
> 
> Eli Zaretskii wrote:
> > I wonder why we need that text in the manual, it doesn't seem to
> > provide any useful actionable info, just general description of an
> > issue.
> 
> The intent is to say that Emacs does not guarantee that its changes to files 
> might not survive power outages and the like. The new section briefly 
> suggests 
> actions to take if this is of concern. Feel free to remove this stuff if you 
> think it so obvious or out-of-scope that it should not be in the manual.

Does anyone else see this text as useful?  I'm not going to remove it
if someone might find it helpful.