Description of problem:
configure the static ipv4 and ipv6 together cause port not able to get dynamic mac address

Version-Release number of selected component (if applicable):
[root@dell-per730-19 ~]# uname -a
Linux dell-per730-19.rhts.eng.pek2.redhat.com 3.10.0-957.el7.x86_64 #1 SMP Thu Oct 4 20:48:51 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
[root@dell-per730-19 ~]# rpm -qa  | grep openvswitch
kernel-kernel-networking-openvswitch-ovs_qinq_dpdk-1.3-35.noarch
openvswitch-ovn-common-2.9.0-95.el7fdp.x86_64
openvswitch-selinux-extra-policy-1.0-10.el7fdp.noarch
openvswitch-2.9.0-95.el7fdp.x86_64
openvswitch-ovn-central-2.9.0-95.el7fdp.x86_64
openvswitch-ovn-host-2.9.0-95.el7fdp.x86_64
[root@dell-per730-19 ~]# 

How reproducible:
every time

Steps to Reproduce:
configured both other_config:subnet and other_config:ipv6_prefix,at the first time the dynamic address is not assigned.
But once I change to set dynamic mac and ipv4 static ip only,the address can be assigned:

[root@dell-per730-57 ~]# ovn-nbctl clear Logical-Switch s2 other_config
[root@dell-per730-57 ~]# ovn-nbctl lsp-del lsp1
[root@dell-per730-57 ~]# ovn-nbctl  set Logical-Switch s2 other_config:subnet=192.168.0.0/16
[root@dell-per730-57 ~]# ovn-nbctl set Logical-switch s2 other_config:ipv6_prefix=2003::0
[root@dell-per730-57 ~]#  ovn-nbctl lsp-add s2 lsp1 -- lsp-set-addresses lsp1 "dynamic 192.168.0.99 2003::99"
[root@dell-per730-57 ~]# ovn-nbctl get Logical-Switch-Port lsp1 dynamic_addresses
[]
[root@dell-per730-57 ~]#  ovn-nbctl get Logical-Switch s2 other_config
{"ipv6_prefix"="2003::0", subnet="192.168.0.0/16"}
[root@dell-per730-57 ~]#
[root@dell-per730-57 ~]# ovn-nbctl get Logical-Switch-Port lsp1 dynamic_addresses
[]
[root@dell-per730-57 ~]#  ovn-nbctl lsp-set-addresses lsp1 "dynamic 192.168.0.99"
[root@dell-per730-57 ~]# ovn-nbctl get Logical-Switch-Port lsp1 dynamic_addresses
"00:00:22:a8:00:64 192.168.0.99 2003::200:22ff:fea8:64"
[root@dell-per730-57 ~]#