bug#30285: dired-do-chmod vs. top line of dired

[Eli Zaretskii]

> From: Tino Calancha <tino.calancha@gmail.com>
> Date: Tue, 30 Jan 2018 00:14:00 +0900
> Cc: 30285@debbugs.gnu.org
> 
> > (Why doesn't it just complain "can't operate on" like it does for the
> > third line, ".".)
> Following patch just do nothing in these cases.  That's OK for me.
> Do you prefer to inform the user in this case that there is no file
> to change the mode?

Yes, I think we should produce some message in these cases.

Thanks.