message: Don't generate empty _redirects.yaml files.
diff: @@ -171,6 +171,7 @@ def write_docs(output_dir,
  os.path.join('/', from_path),
  os.path.join('/', to_path)))
  + if redirects:
  redirects = sorted(redirects)
  template = ('- from: {}\n'
  ' to: {}\n')
  