Comment 3 for bug 1593653

I think we can partially apply https://review.openstack.org/#/c/317949/ to fix this bug. That is removing code at [1].

But before that, we need to remove the deprecated option router_id, so that get_router_ids will always be called in a full sync, and the auto_schedule_routers can be handled there. Removing router_id is reported at bug 1594711

[1] https://github.com/openstack/neutron/blob/b59bb0fcfa41963c0e2f7bcbf34b7e4f4ff5cd08/neutron/api/rpc/handlers/l3_rpc.py#L96-L97