devstack fail when create_k8s_router_fake_service in overcloud

Run nested kuryr-kubernetes, in overcloud get error:
Error Log:
bernetes
2017-06-11 08:43:33.288 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:576 ^[[m^O is_service_enabled kuryr-kubernetes
2017-06-11 08:43:33.325 | ++^[[3242mfunctions-common:is_service_enabled:2191 ^[[m^O return 0
2017-06-11 08:43:33.332 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:577 ^[[m^O [[ stack == \s\t\a\c\k ]]
2017-06-11 08:43:33.339 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:577 ^[[m^O [[ test-config == \i\n\s\t\a\l\l ]]
2017-06-11 08:43:33.346 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:583 ^[[m^O [[ stack == \s\t\a\c\k ]]
2017-06-11 08:43:33.354 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:583 ^[[m^O [[ test-config == \p\o\s\t\-\c\o\n\f\i\g ]]
2017-06-11 08:43:33.362 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:588 ^[[m^O [[ stack == \s\t\a\c\k ]]
2017-06-11 08:43:33.339 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:577 ^[[m^O [[ test-config == \i\n\s\t\a\l\l ]]
2017-06-11 08:43:33.346 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:583 ^[[m^O [[ stack == \s\t\a\c\k ]]
2017-06-11 08:43:33.354 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:583 ^[[m^O [[ test-config == \p\o\s\t\-\c\o\n\f\i\g ]]
2017-06-11 08:43:33.362 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:588 ^[[m^O [[ stack == \s\t\a\c\k ]]
2017-06-11 08:43:33.369 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:588 ^[[m^O [[ test-config == \e\x\t\r\a ]]
2017-06-11 08:43:33.376 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:646 ^[[m^O [[ stack == \s\t\a\c\k ]]
2017-06-11 08:43:33.383 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:646 ^[[m^O [[ test-config == \t\e\s\t\-\c\o\n\f\i\g ]]
2017-06-11 08:43:33.397 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:source:647 ^[[m^O create_k8s_router_fake_service
2017-06-11 08:43:33.407 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:113 ^[[m^O local service_cidr
2017-06-11 08:43:33.413 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:114 ^[[m^O local router_ip
2017-06-11 08:43:33.429 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:115 ^[[m^O local existing_svc_ip
2017-06-11 08:43:33.437 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:116 ^[[m^O local fake_svc_name
2017-06-11 08:43:33.446 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:118 ^[[m^O fake_svc_name=kuryr-svc-router
2017-06-11 08:43:33.453 | +++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:122 ^[[m^O openstack --os-cloud devstack-admin --os-region RegionOne subnet show k8s-service-subnet -c cidr -f value
2017-06-11 08:43:36.224 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:122 ^[[m^O service_cidr=10.0.8.0/24
2017-06-11 08:43:36.242 | +++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:123 ^[[m^O _cidr_range 10.0.8.0/24
2017-06-11 08:43:36.247 | +++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:123 ^[[m^O cut -f2
2017-06-11 08:43:36.256 | +++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:_cidr_range:104 ^[[m^O python - 10.0.8.0/24
2017-06-11 08:43:36.319 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:123 ^[[m^O router_ip=10.0.8.254
2017-06-11 08:43:36.329 | +++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:124 ^[[m^O /usr/local/bin/kubectl get svc --namespace kube-system -o 'jsonpath={.items[?(@.metadata.name=="kuryr-svc-router")].spec.clusterIP}'
2017-06-11 08:43:36.651 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:124 ^[[m^O existing_svc_ip=
2017-06-11 08:43:36.661 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:126 ^[[m^O [[ '' == '' ]]
2017-06-11 08:43:36.675 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:128 ^[[m^O /usr/local/bin/kubectl create -f -
2017-06-11 08:43:36.678 | ++^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:128 ^[[m^O cat
2017-06-11 08:43:36.979 | The Service "kuryr-svc-router" is invalid: spec.clusterIP: Invalid value: "10.0.8.254": provided IP is not in the valid range
2017-06-11 08:43:36.994 | +^[[3242m/opt/stack/kuryr-kubernetes/devstack/plugin.sh:create_k8s_router_fake_service:1 ^[[m^O exit_trap

=======================================================================================================
The k8s-service-subnet is generated in undercloud OpenStack.
$ openstack network create net2
$ openstack subnet create --network net2 --subnet-range 10.0.8.0/24 k8s-service-subnet
$ openstack router add subnet router1 k8s-service-subnet
$ openstack subnet set k8s-service-subnet --dns-nameserver=8.8.8.8
$ openstack subnet show 9906e9cb-c719-4262-abd3-1152b90df4e0
+-------------------------+--------------------------------------+
| Field | Value |
+-------------------------+--------------------------------------+
| allocation_pools | 10.0.8.2-10.0.8.254 |
| cidr | 10.0.8.0/24 |
| created_at | 2017-06-11T08:39:42Z |
| description | |
| dns_nameservers | 10.170.4.29, 8.8.8.8 |
| enable_dhcp | True |
| gateway_ip | 10.0.8.1 |
| host_routes | |
| id | 9906e9cb-c719-4262-abd3-1152b90df4e0 |
| ip_version | 4 |
| ipv6_address_mode | None |
| ipv6_ra_mode | None |
| name | k8s-service-subnet |
| network_id | 68ca7df1-a160-4bcd-a579-8df29a6f8061 |
| project_id | 866aeac4c87c43eeb560aad877546230 |
| revision_number | 4 |
| segment_id | None |
| service_types | |
| subnetpool_id | None |
| updated_at | 2017-06-11T14:20:03Z |
| use_default_subnet_pool | None |
+-------------------------+--------------------------------------+