Download failover means we can now always try github zip urls for dist

src/Composer/Repository/Vcs/GitHubDriver.php

@@ -117,10 +117,6 @@ class GitHubDriver extends VcsDriver
      */
     public function getDist($identifier)
     {
-        if ($this->gitDriver) {
-            return $this->gitDriver->getDist($identifier);
-        }
-
         $url = $this->getApiUrl() . '/repos/'.$this->owner.'/'.$this->repository.'/zipball/'.$identifier;
 
         return array('type' => 'zip', 'url' => $url, 'reference' => $identifier, 'shasum' => '');