Function _simplenews_statistics_absolute(&$body) should skip URLs which are already absolute

Currently, this function applies string replace for any URLs, including URL which is already absolute. Adding following if statement (line 169) before applying preg_replace will fix the issue:

if (!preg_match('/http/', $body)){
$body = preg_replace(
'/(src|href)=(\'|")\//', '$1=$2' . url('', array('absolute' => TRUE)), $body
);