private function rollback()
{
$this->output->writeln(array('', '<error>There was an error while updating the installer.</error>', 'The previous Symfony Installer version has been restored.', ''));
$this->fs->remove($this->newInstallerFile);
if ($this->restorePreviousInstaller) {
$this->fs->copy($this->currentInstallerBackupFile, $this->currentInstallerFile, true);
}
}