--- wp-includes/wp-db.php
+++ wp-includes/wp-db.php
@@ -1483,8 +1482,6 @@
 	 *
 	 * Will not die if wpdb::$show_errors is true
          * 
-         * Will give out ajax response if failed while DOING_AJAX
-	 *
 	 * @since 1.5.0
 	 *
 	 * @param string $message The Error message
@@ -1492,17 +1489,6 @@
 	 * @return false|void
 	 */
 	function bail( $message, $error_code = '500' ) {                
-                if((defined('DOING_AJAX') && DOING_AJAX)) {
-                    $id = isset($_POST['post_ID'])? (int) $_POST['post_ID'] : 0;
-                    $message = new WP_Error('autosave_failed', /*WP_I18N_AUTOSAVE_FAILED*/'Connection to database failed. Couldn\'t autosave.'/*/WP_I18N_AUTOSAVE_FAILED*/);                                        
-                    $x = new WP_Ajax_Response( array(
-                        'what' => 'autosave',                                    
-                        'data' => $message->errors['autosave_failed']['0'],
-                        'id' => $id
-                    ) );
-                    $x->send();
-                    die;
-                }
 		if ( !$this->show_errors ) {                        
 			if ( class_exists( 'WP_Error' ) )
 				$this->error = new WP_Error($error_code, $message);