public function getRootIdentifier()
    {
        if (null === $this->rootIdentifier) {
            $this->process->execute(sprintf('hg tip --template "{node}"'), $output, $this->repoDir);
            $output = $this->process->splitLines($output);
            $this->rootIdentifier = $output[0];
        }

        return $this->rootIdentifier;
    }
public function getRootIdentifier()
    {
        if (null === $this->rootIdentifier) {
            $this->process->execute(sprintf('hg tip --template "{node}"'), $output, $this->repoDir);
            $output = $this->process->splitLines($output);
            $this->rootIdentifier = $output[0];
        }

        return $this->rootIdentifier;
    }
{@inheritDoc}