VersionsSort: WalkVersionsSortDesc,
	}); err != nil {
		// Do not need to retry if we can't list objects on source.
		return err
	}

	// Goroutine to periodically save batch-expire job's in-memory state
	saverQuitCh := make(chan struct{})
	go func() {
		saveTicker := time.NewTicker(10 * time.Second)
		defer saveTicker.Stop()
		for {
			select {