bug#30405: 26.0.91; Incorrect apostrophe translation in ImageMagick error message

[Eli Zaretskii]

> Cc: npostavs@users.sourceforge.net, rgm@gnu.org, gazally@runbox.com,
>  30405@debbugs.gnu.org
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Sun, 11 Feb 2018 09:26:41 -0800
> 
> > The question that bothers me is can a unibyte string inserted or
> > printed into a multibyte buffer be converted to something that will
> > display as a non-ASCII character, not as an octal escape.
> 
> Surely we can arrange for the latter.

I think we already do.  At least I couldn't find a way to display a
raw byte as a non-ASCII Latin character in a unibyte buffer.  If no
one can, we could probably remove that unibyte/multibyte magic in echo
area.