Ext.override

// in app.html
     <link rel="stylesheet" type="text/css" href="http://localhost/extjstest/extjs-4.0.7/resources/css/ext-all.css"/>
    <script type="text/javascript" src="http://localhost/extjstest/extjs-4.0.7/ext-all-dev.js"></script>
    <script type="text/javascript" src="app/overrides/Ext.data.reader.Xml.js"></script>
/* file name  app/overrides/Ext.data.reader.Xml.js */
 Ext.override(Ext.data.reader.Xml,{
      extractData: function(root) {
        var recordName = this.record;

        //<debug>
        if (!recordName) {
            Ext.Error.raise('Record is a required parameter');
        }
        //</debug>

        if (recordName != root.nodeName) {
                //root = Ext.DomQuery.select(recordName, root);
                //patch
                root = Ext.DomQuery.select('>' + recordName, root);
            } else {
                root = [root];
            }
            return this.callParent([root]);
        }
 });