nova.network.manager should improve exception handling

[Nachi Ueno]

Following api call do not handle exceptions well.

(See bad exception handling example in blueprint
 https://blueprints.launchpad.net/openstack-qa/+spec/nova-exception-policy)

NetworkManager.init_host()
FloatingIP.init_host_floating_ips()
FloatingIP.deallocate_for_instance()
NetworkManager.init_host()
NetworkManager.deallocate_for_instance()
NetworkManager.get_instance_nw_info()
NetworkManager._allocate_mac_addresses()
NetworkManager.remove_fixed_ip_from_instance()
NetworkManager.create_networks()
NetworkManager._create_fixed_ips()

[Nachi Ueno (nati-ueno)]

https://github.com/ntt-pf-lab/nova/tree/openstack-qa-nova-872513

[Mark McLoughlin (markmc)]

Moving from FixCommitted to Confirmed since nobody is assigned

[Sean Dague (sdague)]

moving to opinion, as it's so old, it's probably out of date