user/id.go
func NextSystemGID() (int, error) {
	db, gid, err := nextGUID(true)
	db.close()
	return gid, err
}
func NextSystemGID() (int, error) {
	db, gid, err := nextGUID(true)
	db.close()
	return gid, err
}
// NextSystemGID returns the next free system group id to use.