def _StandardizeTargetLabel(label):
  """Convert labels of form //dir/target to //dir/target:target."""
  if label is None:
    return label
  tokens = label.rsplit('/', 1)
  if len(tokens) <= 1:
    return label

  target_base = tokens[0]
  target = tokens[1]

  if '...' in target or ':' in target:
    return label
  return label + ':' + target