Fixes #2181: Raise validation error on invalid prefix_length when allocating next-available prefix
Fixes #2181: Raise validation error on invalid prefix_length when allocating next-available prefix

lampwins/netbox,digitalocean/netbox,lampwins/netbox,digitalocean/netbox,lampwins/netbox,digitalocean/netbox,digitalocean/netbox,lampwins/netbox