bug#28518: Daemon mode only renders the first image file loaded

[Eli Zaretskii]

> From: Noam Postavsky <npostavs@users.sourceforge.net>
> Date: Mon, 16 Oct 2017 06:42:59 -0400
> Cc: damien@cassou.me, 28518@debbugs.gnu.org
> 
> > $ pacman -Qi imagemagick
> > Name            : imagemagick
> > Version         : 6.9.9.14-1
> 
> Damien Cassou <damien@cassou.me> writes:
> 
> > I have a similar problem with a similar message
> >
> >     ImageMagick error: no decode delegate for this image format `PNG' @ 
> > error/constitute.c/ReadImage/504
> >
> > My setup:
> >
> > - Fedora 26
> > - Emacs 25 and 26
> 
> Please try updating imagemagick to 6.9.9.18-1.
> 
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=28633#13

I think this pops up so frequently that it warrants an entry in
etc/PROBLEMS.