subnet_is_ipv6() function does not work for types ipv6_dhcpv6-stateless|stateful

def subnet_is_ipv6(subnet):
    """Common helper for checking network_state subnets for ipv6."""
    # 'static6' or 'dhcp6'
    if subnet['type'].endswith('6'):
        # This is a request for DHCPv6.
        return True
    elif subnet['type'] == 'static' and is_ipv6_addr(subnet.get('address')):
        return True
    return False

Function return false for ipv6_dhcpv6-stateless|stateful, the eni renderer does not add '6' to 'inet' so it's rendered like: 'iface iface0 inet auto|dhcp' not 'iface iface0 inet6 auto|dhcp'