Setting a MachineSet's replicas to "0" does not remove all workers.

Scale a machineset to zero replicas:

```
oc -n openshift-machine-api patch "$(oc -n openshift-machine-api get machineset -o NAME | head -n1)" \
    --type='json' \
    --patch='[ {"op": "replace", "path": "/spec/replicas", "value": 0} ]'
```

watch worker nodes decrease to one:

```
oc get nodes
```

and worker instances decrease to one:

```
openstack server list
```

Worker nodes scale to zero, OpenStack machines named "worker" scale to zero.

https://issues.redhat.com/browse/OSASINFRA-1803