code: def save_configuration_files(self):
          
          try:
              for f in self._configuration_to_save:
                  config_file = os.path.join(self._config_dir, f)
                  backup_file = os.path.join(self._data_dir, f + '.backup')
                  if os.path.isfile(config_file):
                      shutil.copy(config_file, backup_file)
          except IOError:
              logger.exception('unable to create backup copies of configuration files')
          return True
docs: copy postgresql.conf to postgresql.conf.backup to be able to retrive configuration files
              - originally stored as symlinks, those are normally skipped by pg_basebackup
              - in case of WAL-E basebackup (see http://comments.gmane.org/gmane.comp.db.postgresql.wal-e/239)