Comment 8 for bug 1597596

In response to Dr. Rosenboom's comments:
1. "the intention of not deleting the port when rescheduling is that it could be reused on the second compute node."
In our use case, we are using bridged network mode, the network_info allocated initially on first compute is useless and cause adverse side effect. We need to clean up the network_resource associated with the first compute.
2. "Also note that cleanup if the rescheduling fails three times seems to have been implemented in https://bugs.launchpad.net/nova/+bug/1510979."
This is a different issue than what we encounter, in our case, the VM was retried and spawn up on a second compute, there is no "failure" to nova code and there is no chance for the network to get cleaned up.
3. "the self.driver.spawn() call below this code being executed before _allocate_network_async logs the assigned network info."
This is also a separate issue. We like to address the issue that network info was not cleaned up on some code path.