ovs bridge doesn't take IPV6 settings to bridge ifcfg file when creating new bridge during installation

[GUO Larry]

I am installing OpenStack via IPv6 on RHEL7
All the IPs were changed from IPv4 to IPv6 in answer files. Here is my ifcfg-eth0 file before starting installation:
# cat /etc/sysconfig/network-scripts/ifcfg-eth0
DNS2="135.252.128.166"
DNS1="135.252.34.156"
IPADDR="135.251.84.248"
GATEWAY="135.251.84.225"
NETMASK="255.255.255.224"
BOOTPROTO="static"
DEVICE="eth0"
ONBOOT="yes"
IPV6_DEFAULTGW="c5f::1"
IPV6ADDR="c5f::f8/112"
IPV6INIT="yes"

During installation, packstack hang at controller_network.pp step. After check, it waiting for c5f::f8 to be accessible, however, my new bridge file looks like:

# cat ifcfg-br0
IPADDR="135.251.84.248"
GATEWAY="135.251.84.225"
NETMASK="255.255.255.224"
ONBOOT="yes"
DEVICE=br0
NAME=br0
DEVICETYPE=ovs
OVSBOOTPROTO="static"
TYPE=OVSBridge
OVS_EXTRA="set bridge br0 fail_mode=standalone"

The IPv6 settings lost in the bridge ifcfg file. (DNS also missing but no impacting to installation). So, the IPv6 address never reachable. I can add IPv6 configurations to br0 as workaround to let it continue.