fail to set gateway for a ha router

I deployed devstack with ml2 core plugin and df-l3 service plugin. I set l3_ha=True in neutron.conf.
When I trying to set gateway for a ha router, error happened in q-svc:

2018-03-15 07:01:26.277 TRACE neutron.api.v2.resource File "/opt/stack/neutron/neutron/scheduler/l3_agent_scheduler.py", line 338, in _bind_ha_router
2018-03-15 07:01:26.277 TRACE neutron.api.v2.resource plugin, context, candidates)
2018-03-15 07:01:26.277 TRACE neutron.api.v2.resource File "/opt/stack/neutron/neutron/scheduler/l3_agent_scheduler.py", line 369, in _choose_router_agents_for_ha
2018-03-15 07:01:26.277 TRACE neutron.api.v2.resource ordered_agents = plugin.get_l3_agents_ordered_by_num_routers(
2018-03-15 07:01:26.277 TRACE neutron.api.v2.resource AttributeError: 'DFL3RouterPlugin' object has no attribute 'get_l3_agents_ordered_by_num_routers'

Does Dragonflow support l3_ha?