bug#27986: 26.0.50; 'rename-file' can rename files without confirmation

[Eli Zaretskii]

> Cc: p.stephani2@gmail.com, 27986@debbugs.gnu.org
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Tue, 15 Aug 2017 00:00:49 -0700
> 
> Eli Zaretskii wrote:
> > we should not lose the feature that renaming a file on
> > macOS to a different letter-case works without nagging the user with
> > confirmations.
> 
> I was hoping that the current code does that as-is on macOS.

In that case, I have no problems with the changes.  From what Philipp
wrote I concluded, perhaps wrongly, that this is not happening on
macOS.