bug#68849: 30.0.50; font-lock does not flush fontification after calling open-line

[Ihor Radchenko]

This bug was originally reported in
https://orgmode.org/list/c5fb9f63-185c-4e36-b13f-e887a4a29aae@yandex.com

I am not 100% sure if is Emacs bug, but my preliminary testing showed
anomalies in `jit-lock-after-change' -
(put-text-property jit-lock-start jit-lock-end 'fontified nil) somehow
did not apply the text properties. I suspect that I missed something
though.

May someone please help debugging this and figuring out if the problem
is on Emacs side?

Steps to reproduce:

1. Create bug.el:
(require 'org-faces)
(set-face-underline 'org-block-end-line t)
(setq org-fontify-whole-block-delimiter-line t)

2. Create bug.org:
#+begin_src
#+end_src

asd

3. Move point to the end of #+end_src line:
#+end_src<point>

4. M-x open-lien

5. Observe underline face being applied to the empty line _after_
#+end_src.

In GNU Emacs 30.0.50 (build 4, x86_64-pc-linux-gnu, GTK+ Version
 3.24.39, cairo version 1.18.0) of 2024-01-30 built on localhost
Repository revision: 9de29fb5b0396cb3929bd5668604fda076ca5ec4
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101011
System Description: Gentoo Linux

Configured using:
 'configure JAVAC=/etc/java-config-2/current-system-vm/bin/javac'

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
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