public function getRootIdentifier()
    {
        if ($this->fallbackDriver) {
            return $this->fallbackDriver->getRootIdentifier();
        }

        if (null === $this->rootIdentifier) {
            if (! $this->getRepoData()) {
                return $this->fallbackDriver->getRootIdentifier();
            }

            if ($this->vcsType !== 'git') {
                throw new \RuntimeException(
                    $this->url.' does not appear to be a git repository, use '.
                    $this->cloneHttpsUrl.' if this is a mercurial bitbucket repository'
                );
            }

            $mainBranchData = $this->getMainBranchData();
            $this->rootIdentifier = !empty($mainBranchData['name']) ? $mainBranchData['name'] : 'master';
        }

        return $this->rootIdentifier;
    }
public function getRootIdentifier()
    {
        if ($this->fallbackDriver) {
            return $this->fallbackDriver->getRootIdentifier();
        }

        if (null === $this->rootIdentifier) {
            if (! $this->getRepoData()) {
                return $this->fallbackDriver->getRootIdentifier();
            }

            if ($this->vcsType !== 'git') {
                throw new \RuntimeException(
                    $this->url.' does not appear to be a git repository, use '.
                    $this->cloneHttpsUrl.' if this is a mercurial bitbucket repository'
                );
            }

            $mainBranchData = $this->getMainBranchData();
            $this->rootIdentifier = !empty($mainBranchData['name']) ? $mainBranchData['name'] : 'master';
        }

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