bug#30280: async-shell-command-display-buffer doesn't work anymore

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: Eli Zaretskii <eliz@gnu.org>,  Reuben Thomas <rrt@sc3d.org>,  
> <30280@debbugs.gnu.org>
> Date: Wed, 31 Jan 2018 23:44:43 +0200
> 
> > I attach a patch which addresses both bugs.  Its solution for (a) is to
> > make the advice disposable, i.e. it removes itself from the process
> > filter after it has fulfilled its purpose of displaying the output
> > buffer.  A syntactically simpler implementation of this could use a
> > plain boolean switch instead of removing the advice, but IMO the latter
> > is semantically more sound (and possibly more performant in subsequent
> > invocations of the process filter, though this should be irrelevant).
> >
> > WDYT?
> 
> Thanks, I confirm this is the right thing to do and your patch fixes
> the reported issue.

Then please push them to the emacs-26 branch, and thanks.