docs: def clone_from_upstream(pkg_name, repo_url):
          """Clone a non-existent package using the upstream registry."""
          msg = "Spawning a cloning task for %s from upstream due to API req."
          LOG.info(msg % pkg_name)
  
          upstream_url = settings.UPSTREAM_BOWER_REGISTRY
          upstream_pkg = bowerlib.get_package(upstream_url, pkg_name)
  
          if upstream_pkg is None:
              raise Http404
  
          task = tasks.clone_repo.delay(pkg_name, upstream_pkg['url'])
          try:
              result = task.get(timeout=5)
          except tasks.TimeoutError:
              # Not done yet. What to return?
              raise ServiceUnavailable
  
          return result.to_package(repo_url)