src/Composer/Downloader/VcsDownloader.php
public function getVcsReference(PackageInterface $package, $path)
    {
        $parser = new VersionParser;
        $guesser = new VersionGuesser($this->config, $this->process, $parser);
        $dumper = new ArrayDumper;

        $packageConfig = $dumper->dump($package);
        if ($packageVersion = $guesser->guessVersion($packageConfig, $path)) {
            return $packageVersion['commit'];
        }
    }
public function getVcsReference(PackageInterface $package, $path)
    {
        $parser = new VersionParser;
        $guesser = new VersionGuesser($this->config, $this->process, $parser);
        $dumper = new ArrayDumper;

        $packageConfig = $dumper->dump($package);
        if ($packageVersion = $guesser->guessVersion($packageConfig, $path)) {
            return $packageVersion['commit'];
        }
    }
{@inheritDoc}