bug#42184: 27.0.91; org-fontify-whole-heading-line does not work in emacs 27

[Kévin Le Gouguec]

Here is a variant of the previous patch, which correctly resets :extend
to nil if the user disables the relevant options (after reverting the
current buffer, or for newly opened ones).

This ends up looking similar to what Org does for org-hide; IMO this
seems like the most straightforward short-term fix.  In the long run,
these user options would probably deserve :set functions.

>From 07d123c548051eb7f6bbac5c7f5a4e4b8411f976 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?K=C3=A9vin=20Le=20Gouguec?= <kevin.legouguec@gmail.com>
Date: Thu, 9 Jul 2020 16:02:49 +0200
Subject: [PATCH] Fix org-fontify-whole-*-line by setting face extension
 (bug#42184)

* lisp/org/org-compat.el (org--set-faces-extend): New function to set
face extension, for Emacs versions where this attribute exists.
* lisp/org/org.el (org-mode): Call it to set the extend attribute of
relevant faces to the correct value.
---
 lisp/org/org-compat.el | 4 ++++
 lisp/org/org.el        | 6 +++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/lisp/org/org-compat.el b/lisp/org/org-compat.el
index c1aaf17ca2..fcc325e475 100644
--- a/lisp/org/org-compat.el
+++ b/lisp/org/org-compat.el
@@ -101,6 +101,10 @@ org-table1-hline-regexp
   (defun org-time-convert-to-list (time)
     (seconds-to-time (float-time time))))
 
+(defun org--set-faces-extend (faces extend-p)
+  (when (fboundp 'set-face-extend)
+    (mapc (lambda (f) (set-face-extend f extend-p)) faces)))
+
 
 ;;; Emacs < 26.1 compatibility
 
diff --git a/lisp/org/org.el b/lisp/org/org.el
index 568f5b9b87..fb31336ea4 100644
--- a/lisp/org/org.el
+++ b/lisp/org/org.el
@@ -4944,7 +4944,11 @@ org-mode
   ;; Try to set `org-hide' face correctly.
   (let ((foreground (org-find-invisible-foreground)))
     (when foreground
-      (set-face-foreground 'org-hide foreground))))
+      (set-face-foreground 'org-hide foreground)))
+  ;; Set face extension as requested.
+  (org--set-faces-extend '(org-block-begin-line org-block-end-line)
+                         org-fontify-whole-block-delimiter-line)
+  (org--set-faces-extend org-level-faces org-fontify-whole-heading-line))
 
 ;; Update `customize-package-emacs-version-alist'
 (add-to-list 'customize-package-emacs-version-alist
-- 
2.27.0

Should I post this patch to the org-mode mailing list?