The archive.php in 2.5.0 now uses the following condition to check if the script has been run from command line:

if (isset($_SERVER['argv'])) {

Please be aware, that $_SERVER['argv'] may be set on some web environments (such as cgi or php-fpm, I believe). Thus, the script will fail (or rather, display an empty page) on any web environment that sets that particular value, because it tries to run the web archival script as if it was run from a command line. It would probably be more advisable to validate the running environment using PHP_SAPI or php_sapi_name().