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

[Eli Zaretskii <eliz@gnu.org>]

> Cc: Kostas Papadakis <papadakis.k@yandex.com>
> From: Ihor Radchenko <yantar92@posteo.net>
> Date: Wed, 31 Jan 2024 12:44:09 +0000
> 
> 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.

Stefan, any suggestions?