Comment 11 for bug 1052535

The patch I provided does not address the base IP netns.
It addresses 2 issues:
1. openstack ensuring it is cleaning up the created resources it has created: it ensures cleanup of subnets upon deletion of networks.
2. it results in subnet deletion notifications being sent out for agents like dhcp agent which will make them cleanup their resources (for dhcpagent its dnsmasq) more promptly instead of waiting for a manual cleanup