def start(self):
        """Ensure coverage rc file rsynced if appropriate."""

        if self.cov_config and os.path.exists(self.cov_config):
            self.config.option.rsyncdir.append(self.cov_config)

        self.cov = coverage.coverage(source=self.cov_source,
                                     data_file=self.cov_data_file,
                                     config_file=self.cov_config)
        self.cov.erase()
        self.cov.start()
        self.cov.config.paths['source'] = [self.topdir]