bug#33255: 27.0.50; expand-file-name: default directory expanded twice if relative

[Eli Zaretskii]

> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Wed, 14 Nov 2018 10:17:59 -0800
> Cc: 33255@debbugs.gnu.org, immerrr again <immerrr@gmail.com>,
>       Noam Postavsky <npostavs@gmail.com>
> 
> > I'm a bit disappointed to see that a relative HOME is now documented
> > in the Emacs manuals, since IMO it lends legitimacy to a questionable
> > usage. I don't see it mentioned in eg the bash manual.
> > I also don't see why it is in NEWS since it is described as
> > a bug fix, and those aren't normally mentioned.
> 
> My initial reaction was the same as yours, which is why my original fix 
> didn't document the change in the manual or in NEWS. Eli felt otherwise, 
> though.

I agree that we should discourage relative $HOME, so I added text to
the documentation to that effect.