Comment 2 for bug 1867577

The detail about sriov is actually not particularly relevant, the important bit is that this bug is triggered when neutron-openvswitch is redeployed a second time to the same machine.

To reproduce:
1. juju deploy nova-compute app1 # let's assume this yields app1/0 on machine 0
2. juju relate neutron-openvswitch app1
3. juju deploy ubuntu --to 0
4. juju remove-unit app1/0 # machine 0 won't be released due to step 3
5. juju deploy nova-compute app2 --to 0
6. juju relate neutron-openvswitch app2