bug#41570: 26.3; dired chown

[Eli Zaretskii]

> From: Richard Stallman <rms@gnu.org>
> Date: Fri, 04 Sep 2020 23:17:42 -0400
> Cc: 41570@debbugs.gnu.org, stefan@marxist.se, blicher@comcast.net
> 
> Perhaps the Dired O command should give an immediate error, perhaps
> 
>   Changing a file's owner not supported on this OS.  Switch to GNU/Linux.

But this is not true: if one has a 'chown' command available (and I
do), it will and should work as intended.