src/Composer/Util/Filesystem.php
private function resolveSymlinkedDirectorySymlink($pathname)
    {
        if (!is_dir($pathname)) {
            return $pathname;
        }

        $resolved = rtrim($pathname, '/');

        if (!strlen($resolved)) {
            return $pathname;
        }

        return $resolved;
    }
private function resolveSymlinkedDirectorySymlink($pathname)
    {
        if (!is_dir($pathname)) {
            return $pathname;
        }

        $resolved = rtrim($pathname, '/');

        if (!strlen($resolved)) {
            return $pathname;
        }

        return $resolved;
    }
resolve pathname to symbolic link of a directory

@param string $pathname directory path to resolve

@return string resolved path to symbolic link or original pathname (unresolved)