Comment 1 for bug 837867

In nova/network/manager.py:

NetworkManager's add_fixed_ip_to_instance calls _allocate_fixed_ips without vpn or requested_networks parameters.

FlatManager's _allocate_fixed_ips will fail if throw an exception if requested_networks is not provided

RPCAllocateFixedIP's _allocate_fixed_ips will throw an exception if vpn or requested_networks is not provided (this bug report)

Either add_fixed_ip_to_instance needs to be fixed to pass the required parameters, or (more likely) _allocate_fixed_ips needs to be a little more flexible in what they accept.