How to find out Magento version if only files backup available

If you wish to find out Magento version and only files backup available check file app/Mage.php function getVersionInfo()

    /**
     * Gets the detailed Magento version information
     * @link http://www.magentocommerce.com/blog/new-community-edition-release-process/
     *
     * @return array
     */
    public static function getVersionInfo()
    {
        return array(
            'major'     => '1',
            'minor'     => '4',
            'revision'  => '0',
            'patch'     => '1',
            'stability' => '',
            'number'    => '',
        );
    }