change colspan based on context

Resources/views/CRUD/base_list.html.twig

@@ -73,7 +73,7 @@ file that was distributed with this source code.
 
                 {% block table_footer %}
                     <tr>
-                        <th colspan="{{ admin.list.elements|length - 1 }}">
+                        <th colspan="{{ admin.list.elements|length - (app.request.isXmlHttpRequest ? 2 : 1) }}">
                             {{ admin.datagrid.pager.page }} / {{ admin.datagrid.pager.lastpage }} -
                             {{ "label_export_download"|trans({}, "SonataAdminBundle") }}
                             {% for format in admin.getExportFormats() %}