I'll have to do the bulk of your requests tomorrow, as this is happening on
my work machine, and I'm now at home.
One thing I will say is that my ~ is a UNC path to a network share, not a
local drive mapping. Not sure if that matters or not.

On 18 June 2015 at 17:13, Eli Zaretskii <eliz@gnu.org> wrote:

> > Date: Thu, 18 Jun 2015 13:45:06 +0100
> > From: Bryan Childs <godeater@gmail.com>
> >
> > (file-in-directory-p "~/.emacs.d/elpa/magit/" "~\\.emacs.d\\elpa")
> > nil
> > (file-in-directory-p "~/.emacs.d/elpa/magit-20150608.1139/"
> > "~\\.emacs.d\\elpa")
> > nil
>
> I cannot reproduce this problem on my Windows machine.  I get t, not
> nil.  (I don't have a 'magit' sub-directory, so I tried with a
> different name, but it shouldn't matter.)
>
> So there's some other factor at work here.
>
> Where exactly is your "~" directory?  Please show its full absolute
> Windows file name.  Also, what do you see if you evaluate the
> following expressions, one by one, using 'M-:' ?
>
>   (file-attributes "~/.emacs.d/elpa/magit" 'string)
>   (file-attributes "~/.emacs.d/elpa" 'string)
>   (file-attributes "~/.emacs.d" 'string)
>   (file-attributes "~" 'string)
>
> Finally, please try evaluating this in "emacs -Q":
>
>   (file-in-directory-p "~/.emacs.d/elpa/magit/" "~\\.emacs.d\\elpa")
>
> Do you still get nil in "emacs -Q"?
>
> Thanks.
>