Fixed blank lines.

src/Composer/Downloader/HgDownloader.php

@@ -19,7 +19,6 @@ use Composer\Package\PackageInterface;
  */
 class HgDownloader implements DownloaderInterface
 {
-
     /**
      * {@inheritDoc}
      */

src/Composer/Repository/Vcs/HgDriver.php

@@ -58,6 +58,7 @@ class HgDriver implements VcsDriverInterface
             exec(sprintf('cd %s && hg tip --template "{rev}:{node|short}" --color never', $tmpDir), $output);
             $this->rootIdentifier = $output[0];
         }
+        
         return $this->rootIdentifier;
     }