bug#31737: 26.1.50; Gnus does not use mailutils movemail

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: m43cap@yandex.com,  larsi@gnus.org,  31737@debbugs.gnu.org
> Date: Thu, 14 Jun 2018 14:14:28 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> From: Robert Pluim <rpluim@gmail.com>
> >> Cc: Eli Zaretskii <eliz@gnu.org>,  Colin Baxter <m43cap@yandex.com>,  
> >> 31737@debbugs.gnu.org
> >> Date: Wed, 13 Jun 2018 16:08:53 +0200
> >> 
> >> Eli, were you thinking that mail-source should duplicate the movemail
> >> detection logic in rmail? Or should it just assume Mailutils movemail
> >> and pass '--emacs'?
> >
> > The former.
> 
> Something like this? Testing definitely required by someone who uses
> mailutils movemail for Gnus. Not sure this is emacs-26 material
> anymore.

We could install on emacs-26 something much simpler: just call
"movemail", without assuming it's in exec-directory, if
mail-source-movemail-program is nil, and don't use the "--emacs"
option.

Thanks.