protected function cleanupOldBackups($rollbackDir)
    {
        $finder = $this->getOldInstallationFinder($rollbackDir);

        $fileSystem = new Filesystem;
        foreach ($finder as $file) {
            $file = (string) $file;
            $this->getIO()->writeError('<info>Removing: ' . $file . '</info>');
            $fileSystem->remove($file);
        }
    }