Use old name default text on rename.

lib/gollum/frontend/public/gollum/javascript/gollum.js

@@ -118,10 +118,8 @@ $(document).ready(function() {
     $('#minibutton-rename-page').click(function(e) {
       e.preventDefault();
 
-      var path = $(this).data('path');
-      if (path) {
-        path = path + '/';
-      }
+      var path = window.location.pathname;
+      var oldName = path.substring(path.lastIndexOf('/')+1);
 
       $.GollumDialog.init({
         title: 'Rename Page',
@@ -130,7 +128,7 @@ $(document).ready(function() {
             id:   'name',
             name: 'Rename to',
             type: 'text',
-            defaultValue: path || ''
+            defaultValue: oldName || ''
           }
         ],
         OK: function( res ) {
@@ -138,8 +136,7 @@ $(document).ready(function() {
           if ( res['name'] ) {
             name = res['name'];
           }
-          var path = window.location.pathname;
-          var oldName = path.substring(path.lastIndexOf('/')+1);
+
           var msg = 'Renamed ' + oldName + ' to ' + name;
           jQuery.ajax( {
             type: 'POST',