Made CookieStorage account for the overhead added by the underlying cookie encoding

        unstored_messages = []

        encoded_data = self._encode(messages)

        if self.max_cookie_size:

            while encoded_data and len(encoded_data) > self.max_cookie_size:

            # data is going to be stored eventually by CompatCookie, which

            # adds it's own overhead, which we must account for.

            def stored_length(val):

                return len(CompatCookie().value_encode(val)[1])

            while encoded_data and stored_length(encoded_data) > self.max_cookie_size:

                if remove_oldest:

                    unstored_messages.append(messages.pop(0))

                else: