bug#23186: 25.0.92; Tramp: Windows does not always set COMSPEC, tramp blows up in a string-match

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: Jerry Asher <ja2038@gmail.com>,  23186@debbugs.gnu.org
> Date: Sat, 02 Apr 2016 21:37:51 +0200
> 
> The Tramp maintainers could check, whether COMSPEC is set, and raise a
> verbose warning in case it isn't. Refusing further work.

That'd be fine with me.

> Shall I commit this to the emacs-25 branch, or to master?

emacs-25, I guess.