tax_input does not work with category slugs

[linguasite]

When inserting/updating a post, the slugs of custom taxonomies can be stored in the tax_input array and will be assigned to the post or created if they do no exist.
However, the category taxonomy array in tax_input must contain the term_id's of the categories, otherwise the values will be ignored.

See /wp_includes/post.php line 2532.

Any ideas why this happens?

[mdawaffe]

This is intentional. Hierarchical taxonomies must use IDs since multiple terms can have the same slug as long as they belong to different branches/depths of the hierarchy.

​http://core.trac.wordpress.org/browser/trunk/wp-includes/post.php?rev=17298#L2877

[linguasite]

OK, got it, thanks.