bug#20839: 25.0.50; file-in-directory-p doesn't understand windows backslashes

[Eli Zaretskii]

> Date: Wed, 17 Jun 2015 21:13:13 +0100
> From: Artur Malabarba <bruce.connor.am@gmail.com>
> Cc: 20839@debbugs.gnu.org
> 
> I was aiding someone remotely and I assumed this was the issue. I'll ask them
> to file a bug report themselves. 

Yes, please.

Just FYI, a call to file-truename or expand-file-name converts all
backslashes into forward slashes.  And file-in-directory-p calls
file-truename on both its arguments.  So the favor of the slashes
cannot possibly be the culprit here, at least not in this simple way.