configuration.graph.edit.js.php
...
function getOnlyHostParam() {
var param = '';

jQuery(document).ready(function() {
if (<?php echo $this->data['is_template'] ? 'true' : 'false'; ?>)

{ >> param = '&only_hostid=' + '<?php echo $this->data['hostid']; ?>'; }

else

{ param = '&real_hosts=1'; }

});

return param;
}
...
String <?php echo $this->data['hostid']; ?> not quoted in original file and list of item is empty.