neutron ipv6 support

has IPv6 been fully supported by neutron? I tried to use it by creating a network with both ipv4 and ipv6 subnets. However, once the ipv6 subnet is added, the dnsmasq can not be restarted:

Command: ['sudo', '/usr/local/bin/neutron-rootwrap', '/etc/neutron/rootwrap.conf', 'NEUTRON_RELAY_SOCKET_PATH=/opt/stack/data/neutron/dhcp/lease_relay', 'NEUTRON_NETWORK_ID=fe7b4d55-1ae5-4de1-b515-0f6fadd7f884', 'ip', 'netns', 'exec', 'qdhcp-fe7b4d55-1ae5-4de1-b515-0f6fadd7f884', 'dnsmasq', '--no-hosts', '--no-resolv', '--strict-order', '--bind-interfaces', '--interface=tapb31378a5-27', '--except-interface=lo', '--pid-file=/opt/stack/data/neutron/dhcp/fe7b4d55-1ae5-4de1-b515-0f6fadd7f884/pid', '--dhcp-hostsfile=/opt/stack/data/neutron/dhcp/fe7b4d55-1ae5-4de1-b515-0f6fadd7f884/host', '--dhcp-optsfile=/opt/stack/data/neutron/dhcp/fe7b4d55-1ae5-4de1-b515-0f6fadd7f884/opts', '--dhcp-script=/usr/local/bin/neutron-dhcp-agent-dnsmasq-lease-update', '--leasefile-ro', '--dhcp-range=set:tag0,fd00:1::,static,120s', '--dhcp-range=set:tag1,10.0.0.0,static,120s', '--conf-file=', '--domain=openstacklocal']
Exit code: 1
Stdout: ''
Stderr: '\ndnsmasq: bad command line options: only one tag allowed\n' execute /opt/stack/neutron/neutron/agent/linux/utils.py:59

dnsmasq doesn't like two dhcp-range arguments with different tags in the command line. I'm using dnsmasq 2.59, which seems to be the latest supported by ubuntu.

Also note if I create a network with ipv6 subnet only, nova boot failed to bring up instances, indicating that ipv4 subnet is required.

Any help is appreciated.

thanks,
Robert