bug#23779: 25.0.95; consing "SHELLVAR" onto process-environment doesn't remove it from subprocess env

[Eli Zaretskii]

> Cc: 23779@debbugs.gnu.org, npostavs@users.sourceforge.net
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Tue, 21 Jun 2016 18:24:38 +0300
> 
> On 06/21/2016 06:21 PM, Eli Zaretskii wrote:
> 
> > Please show a patch you have in mind.
> 
> The one in http://debbugs.gnu.org/cgi/bugreport.cgi?bug=23769#86.

Looks OK to me.  (For some reason, I was under the impression that it
doesn't necessarily fix the problem.)