src/Composer/Repository/Vcs/SvnDriver.php
protected static function normalizeUrl($url)
    {
        $fs = new Filesystem();
        if ($fs->isAbsolutePath($url)) {
            return 'file://' . strtr($url, '\\', '/');
        }

        return $url;
    }
protected static function normalizeUrl($url)
    {
        $fs = new Filesystem();
        if ($fs->isAbsolutePath($url)) {
            return 'file://' . strtr($url, '\\', '/');
        }

        return $url;
    }
An absolute path (leading '/') is converted to a file:// url.

@param string $url

@return string