Fetch the initial file (before the change) to a folder

        If the file is newly added, then `None` will be returned.

        :param file_folder: the folder to store the file
        :return: the :class:`string` object
        :rtype: string

def fetchBeforeStateFile(self, file_folder):
        """Fetch the initial file (before the change) to a folder

        If the file is newly added, then `None` will be returned.

        :param file_folder: the folder to store the file
        :return: the :class:`string` object
        :rtype: string
        """

        if u"true" == self.before:
            self.log.info("This file is newly added. No previous file")
        else:
            self.log.info("Fetching initial file of this Change<%s>:" % self)
            return self._fetchFile(self.before, file_folder, override=False)