bug#20906: 25.0.50;

[Eli Zaretskii]

> From: Mike FABIAN <mfabian@redhat.com>
> Cc: 20906@debbugs.gnu.org
> Date: Mon, 05 Oct 2015 08:30:12 +0200
> 
> Eli Zaretskii <eliz@gnu.org> さんはかきました:
> 
> Eli> What is your value of selection-coding-system?
> 
> Mike> nil
> 
> Eli> Does it help to set it to utf-8 or compound-text-with-extensions?
> 
> Unfortunately not, I had already tried that.

The only way to debug this is to track the data we receive from the X
selection in xselect.c all the way to mouse-yank-primary, and see
what's going on there.  Can you do that?