Allow 'post_type' passed as an arg to get_terms (useful for taxonomies shared between post types)

gistfile1.php

/**
 * terms_clauses
 *
 * filter the terms clauses in get_terms(), allow post_type arg 
 *
 * @param $clauses array
 * @param $taxonomy string
 * @param $args array
 * @return array
 * @author Jessica Yazbek
**/
function terms_clauses($clauses, $taxonomy, $args)
{
	global $wpdb;
	
	// if post_type set, don't return terms that don't relate to the current post type
	$post_type = $args['post_type'] ? $args['post_type'] : false;
			
	if ($post_type)
	{
		$clauses['join'] .= " LEFT JOIN $wpdb->term_relationships AS r ON r.term_taxonomy_id = tt.term_taxonomy_id INNER JOIN $wpdb->posts AS p ON p.ID = r.object_id";
		$clauses['where'] .= " AND p.post_type='$post_type'";	
		$clauses['where'] .= " GROUP BY t.term_id";
	}
	return $clauses;
}
add_filter('terms_clauses', 'terms_clauses', 1000, 3);