bug#67360: 29.1; MH-E forwarded email has a mangled default Subject header

[Eli Zaretskii <eliz@gnu.org>]

> cc: Mike Kupfer <kupfer@rawbw.com>,
>     Chris Siebenmann <cks.emacsbugs-01@cs.toronto.edu>,
>     67360@debbugs.gnu.org
> From: Bill Wohler <wohler@newt.com>
> Comments: In-reply-to Bill Wohler <wohler@newt.com>
>    message dated "Sat, 30 Dec 2023 14:05:29 -0800."
> Date: Sun, 31 Dec 2023 08:44:40 -0800
> 
> Eli,
> 
> Would you prefer that I apply Mike's patch to emacs-29 or master?
> 
> > diff --git a/lisp/mh-e/mh-comp.el b/lisp/mh-e/mh-comp.el
> > index 92d31bf1826..0d1dcdf626a 100644
> > --- a/lisp/mh-e/mh-comp.el
> > +++ b/lisp/mh-e/mh-comp.el
> > @@ -574,7 +574,7 @@ mh-forward
> >          (setq orig-subject (mh-get-header-field "Subject:")))
> >        (let ((forw-subject
> >               (mh-forwarded-letter-subject orig-from orig-subject)))
> > -        (mh-insert-fields "Subject:" forw-subject)
> > +        (mh-modify-header-field "Subject" forw-subject t)
> >          (goto-char (point-min))
> >          ;; Set the local value of mh-mail-header-separator according to what is
> >          ;; present in the buffer...

If you think it's safe enough for the release branch, emacs-29 is fine
with me.

Thanks.