func (h *dbHashTree) PutFile(path string, objects []*pfs.Object, size int64) error {
	return h.putFile(path, objects, nil, size, false)
}
func (h *dbHashTree) PutFile(path string, objects []*pfs.Object, size int64) error {
	return h.putFile(path, objects, nil, size, false)
}
// PutFile appends data to a file (and creates the file if it doesn't exist).