Support tax queries using term_taxonomy_id without specifying a taxonomy
|Reported by:||helen||Owned by:|
Taxonomy queries using term_taxonomy_id don't actually check to see if the terms exist in the specified taxonomy. So long as an existing taxonomy is used, it allows you to query across multiple taxonomies in one segment of the query. We should officially support not specifying a taxonomy if using term_taxonomy_id as the field, and do the magic to make include_children work.