bug#7513: 24.0.50; shell-command-default-error-buffer should always append to the bottom

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: jidanni@jidanni.org,  rfrancoise@debian.org,  7513@debbugs.gnu.org
> Date: Fri, 23 Aug 2019 02:14:39 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I'm not sure I understand: you want to lose the ^L separators?  Or
> > something else?
> 
> Keep the ^L separators, but add the output at end-of-buffer instead of
> at point, which it currently does.

So all you need to do is move point to EOB before adding the next
error?  If so, that's fine with me, and probably something that was
just missed, assuming point will never move from there anyway.