Comment 4 for bug 1442771

The one works: neutron subnet-create network1 10.10.1.0/24 --name subnet1

In the old way, both name and CIDR is positional arguments, you can separate them, argparse can still parse it.
With subnetpool, CIDR is optional positional arguments, when you have another parameter in between, it cannot parse it right.
Looking to see if we have better solution.