Index: wp-admin/admin-ajax.php
===================================================================
--- wp-admin/admin-ajax.php	(revision 17533)
+++ wp-admin/admin-ajax.php	(working copy)
@@ -939,12 +939,10 @@
 
 		$last_user = get_userdata( $last );
 		$last_user_name = $last_user ? $last_user->display_name : __( 'Someone' );
-		$data = new WP_Error( 'locked', sprintf(
-			$_POST['post_type'] == 'page' ? __( 'Autosave disabled: %s is currently editing this page.' ) : __( 'Autosave disabled: %s is currently editing this post.' ),
-			esc_html( $last_user_name )
-		) );
+		$data = __( 'Autosave disabled.' );
 
 		$supplemental['disable_autosave'] = 'disable';
+		$supplemental['alert'] = sprintf( __( '%s is currently editing this article. If you update it, you will overwrite the changes.' ), esc_html( $last_user_name ) );
 	}
 
 	if ( 'page' == $post->post_type ) {
Index: wp-includes/js/autosave.dev.js
===================================================================
--- wp-includes/js/autosave.dev.js	(revision 17533)
+++ wp-includes/js/autosave.dev.js	(working copy)
@@ -101,11 +101,11 @@
 				}
 				delete sup['session_expired'];
 			}
-			jQuery.each(sup, function(selector, value) {
-				if ( selector.match(/^replace-/) ) {
-					jQuery('#'+selector.replace('replace-', '')).val(value);
-				}
-			});
+
+			if ( sup['alert'] ) {
+				jQuery('#postdivrich').before('<div class="error below-h2"><p>' + sup['alert'] + '</p></div>');
+				alert( sup['alert'] );
+			}
 		}
 
 		// if no errors: add slug UI