Network removal for service seems not working

Issue type:bugs?

OS Version/build: ubuntu 18

App version: 18.06.0-ce-rc2

Steps to reproduce:

docker network create -d overlay test_network
docker service create --name test_service -p 10:80 nginx:latest
docker service update --network-add test_network test_service
docker service update --network-rm ingress test_service

I don’t know what am I missing or actually a bug, it did’t show any error bug ingress never removed