bug#38193: 26.2; Editing a message in RMAIL should trigger an update to its summary line

[Eli Zaretskii]

> Date: Wed, 13 Nov 2019 00:34:00 -0500 (EST)
> From: Ed Sabol via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Steps:
> 1. Open an existing RMAIL file with multiple messages in rmail-mode.
> 2. Press "h" to generate the corresponding rmail-summary buffer.
> 3. Hit "e" to edit some message.
> 4. Change the Subject: header of the message in some noticeable way.
> 5. Press C-c C-c to finish editing the message.
> 
> Result:
> The corresponding summary line for the edited message is not updated to
> reflect the message's new Subject: header. I expect that it should.
> It used to work like that in older Emacs, pre 22.x for sure, so I
> consider this to be a regression, albeit a very old one!
> 
> Same for other headers like From: and To:.

Thanks.  Does the patch below fix this?

diff --git a/lisp/mail/rmailedit.el b/lisp/mail/rmailedit.el
index 01d5524..02ca2a8 100644
--- a/lisp/mail/rmailedit.el
+++ b/lisp/mail/rmailedit.el
@@ -340,10 +340,11 @@ rmail-cease-edit
         ;; Delete previous body.  This must be after all insertions at the end,
         ;; so the marker for the beginning of the next message isn't messed up.
         (delete-region end (point-max)))
-      (rmail-set-attribute rmail-edited-attr-index t))
-;;;??? BROKEN perhaps.
-;;;    (if (boundp 'rmail-summary-vector)
-;;;    (aset rmail-summary-vector (1- rmail-current-message) nil))
+      (rmail-set-attribute rmail-edited-attr-index t)
+      (if (rmail-summary-exists)
+          (let ((msgnum rmail-current-message))
+            (with-current-buffer rmail-summary-buffer
+              (rmail-summary-update-line msgnum)))))
     (rmail-show-message)
     (rmail-toggle-header (if pruned 1 0))
     ;; Restore mime display state.