bug#20906: 25.0.50;

[Eli Zaretskii]

> From: Mike FABIAN <mfabian@redhat.com>
> Date: Sat, 03 Oct 2015 15:15:54 +0200
> 
> I see the same with Emacs 25.0.50.1 when pasting from rxvt-unicode
> or firefox into Emacs using the mouse button. The pasted text does
> not have to come from an URL, it happens with any text pasted
> from firefox.

What is your value of selection-coding-system?