bug#48740: 28.0.50; Composition text property is not always honoured

[Ihor Radchenko <yantar92@gmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

> No, it is also subdivided into two separate regions, each one of 3
> characters.  And that's why it doesn't work: the display engine
> expects that the composed text should be covered by a single text
> property which specifies the length (7 - 0 = 7) that is equal to the
> length of the covered text (301 - 294 = 7).
>
> So the problem is caused by whatever code in org-agenda-redo-all that
> "breaks" the composition property into 2 separate adjacent properties.

Yet, the same "broken" property does work in step 6... And in both cases
the composition properties of the two regions are same. The two
intervals are there because other properties in the list are not same,
as I understand.

The only possibility I can think about is that compositions in the two
intervals are 'eq at step 6, but only 'equal at step 8. (How on Earth
can one debug this???)

Best,
Ihor