Index: src/wp-includes/taxonomy.php
===================================================================
--- src/wp-includes/taxonomy.php	(revision 55545)
+++ src/wp-includes/taxonomy.php	(working copy)
@@ -2711,7 +2711,7 @@
  * @param int              $object_id The object to relate to.
  * @param string|int|array $terms     A single term slug, single term ID, or array of either term slugs or IDs.
  *                                    Will replace all existing related terms in this taxonomy. Passing an
- *                                    empty value will remove all related terms.
+ *                                    empty array will remove all related terms.
  * @param string           $taxonomy  The context in which to relate the term to the object.
  * @param bool             $append    Optional. If false will delete difference of terms. Default false.
  * @return array|WP_Error Term taxonomy IDs of the affected terms or WP_Error on failure.
@@ -2725,6 +2725,10 @@
 		return new WP_Error( 'invalid_taxonomy', __( 'Invalid taxonomy.' ) );
 	}
 
+	if ( empty( $terms ) ) {
+		$terms = array();
+	}
+
 	if ( ! is_array( $terms ) ) {
 		$terms = array( $terms );
 	}