bug#41626: 28.0.50; activating mark breaks RTL shaping in etc/HELLO (auto-composition-mode)

[Basil L. Contovounesios]

Pip Cet <pipcet@gmail.com> writes:

> Recipe:
> start emacs -Q etc/HELLO
> move point to character position 358 (ARABIC LETTER SEEN)
> hit C-SPC to activate the mark
>
> Expected result:
> mark is activated, no change to shaping
>
> Actual result:
> The character at position 357 is no longer composed with the one at
> position 358. (screenshot with-mark.png) whereas it was composed
> before (screenshot without-mark.png)
>
> The same thing works fine in a separate buffer in an RTL paragraph.

FWIW, a similar thing was discussed in bug#35721.

-- 
Basil