if c.db_repo_scm_instance.alias == 'hg':

                # patch and reset hooks section of UI config to not run any

                # hooks on fetching archives with subrepos

                for k, v in c.db_repo_scm_instance._repo.ui.configitems('hooks'):

                    c.db_repo_scm_instance._repo.ui.setconfig('hooks', k, None)

            cs = c.db_repo_scm_instance.get_changeset(revision)

            content_type = settings.ARCHIVE_SPECS[fileformat][0]

        except ChangesetDoesNotExistError:

            return _('Unknown revision %s') % revision

        except EmptyRepositoryError:

            return _('Empty repository')

        except (ImproperArchiveTypeError, KeyError):

            return _('Unknown archive type')

        from kallithea import CONFIG

        rev_name = cs.raw_id[:12]

        archive_name = '%s-%s%s' % (safe_str(repo_name.replace('/', '_')),

                                    safe_str(rev_name), ext)

        archive_path = None

        cached_archive_path = None

        archive_cache_dir = CONFIG.get('archive_cache_dir')

            if not os.path.isdir(archive_cache_dir):

                os.makedirs(archive_cache_dir)

            cached_archive_path = os.path.join(archive_cache_dir, archive_name)

            if os.path.isfile(cached_archive_path):

                log.debug('Found cached archive in %s', cached_archive_path)

                archive_path = cached_archive_path

            else:

                log.debug('Archive %s is not yet cached', archive_name)

        if archive_path is None:

            # generate new archive

            fd, archive_path = tempfile.mkstemp()

            log.debug('Creating new temp archive in %s', archive_path)

            with os.fdopen(fd, 'wb') as stream:

                cs.fill_archive(stream=stream, kind=fileformat, subrepos=subrepos)

                # stream (and thus fd) has been closed by cs.fill_archive

            if cached_archive_path is not None:

                # we generated the archive - move it to cache

                log.debug('Storing new archive in %s', cached_archive_path)

                shutil.move(archive_path, cached_archive_path)

                archive_path = cached_archive_path

        def get_chunked_archive(archive_path):

            stream = open(archive_path, 'rb')