class ActionDispatch::Response

def before_sending
  # Normally we've already committed by now, but it's possible
  # (e.g., if the controller action tries to read back its own
  # response) to get here before that. In that case, we must force
  # an "early" commit: we're about to freeze the headers, so this is
  # our last chance.
  commit! unless committed?
  headers.freeze
  request.commit_cookie_jar! unless committed?
end