Index: wp-includes/taxonomy.php
===================================================================
--- wp-includes/taxonomy.php	(revision 21814)
+++ wp-includes/taxonomy.php	(working copy)
@@ -1182,12 +1182,10 @@
 	global $wpdb;
 	$empty_array = array();
 
-	$single_taxonomy = false;
-	if ( !is_array($taxonomies) ) {
-		$single_taxonomy = true;
-		$taxonomies = array($taxonomies);
-	}
-
+	$single_taxonomy = ( ! is_array( $taxonomies ) || 1 === count( $taxonomies ) );
+	if ( ! is_array( $taxonomies ) )
+		$taxonomies = array( $taxonomies );
+	
 	foreach ( $taxonomies as $taxonomy ) {
 		if ( ! taxonomy_exists($taxonomy) ) {
 			$error = new WP_Error('invalid_taxonomy', __('Invalid taxonomy'));