Terms are uselessly counted when saving a post

[Chouby]

This occurs even when terms have not been modified and when the post status has not changed. This is due to _update_term_count_on_transition_post_status not checking if the post status has been modified.

[johnbillion]

What about the situation where a published post gets its terms changed but the status doesn't change? It looks like this change would cause the term count for newly added terms to get out of sync.

[Chouby]

In that case, wp_set_object_terms calls wp_update_term_count, so the term count should be correctly udpated.

The modification ensures that term counts are only updated when the post's status has truly changed. This reduces unnecessary operations, improving performance when there is no status change on a post.

[pbearne]

refreshed patch

[johnbillion]

In 60365:

Taxonomy: Avoid unnecessarily recalculating term counts when a post is updated and its status is unchanged.

If the terms of the post are changed then the term recounting is still handled by wp_update_term_count() inside wp_set_object_terms().

Props pbearne, johnbillion, peterwilsoncc, Chouby

Fixes #42522