bug#25183: 26.0.50; expanding quoted file name on w32

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Date: Tue, 13 Dec 2016 09:30:18 +0100
> Cc: 25183@debbugs.gnu.org
> 
> It is not an annoyance coming from a user's bug report; I've stumbled
> over this when running tramp-tests.el under many different environments.
> 
> (expand-file-name "/:/~/path/./file") => "/:c:/~/path/file"
> 
> looks better, althoug the volume drive would still disturb me. But
> that's my personal preference, the result might be OK on MS Windows.
> 
> Eli?

I will look into this in a couple of days.