Sanity check for 'family' arg
Sanity check for 'family' arg

We require 'family', ie the wanted address family of the new prefix, in
case of from-pool (since a pool can contain both IPv4 and IPv6), but
disallow it in case of 'from-prefix' as it is obvious from the passed
prefixes which address family is appropriate.

garberg/NIPAP,SoundGoof/NIPAP,fredsod/NIPAP,bbaja42/NIPAP,SpriteLink/NIPAP,ettrig/NIPAP,garberg/NIPAP,garberg/NIPAP,plajjan/NIPAP,garberg/NIPAP,fredsod/NIPAP,fredsod/NIPAP,bbaja42/NIPAP,SpriteLink/NIPAP,ettrig/NIPAP,plajjan/NIPAP,fredsod/NIPAP,bbaja42/NIPAP,garberg/NIPAP,bbaja42/NIPAP,bbaja42/NIPAP,fredsod/NIPAP,fredsod/NIPAP,SoundGoof/NIPAP,SpriteLink/NIPAP,plajjan/NIPAP,SpriteLink/NIPAP,garberg/NIPAP,plajjan/NIPAP,ettrig/NIPAP,ettrig/NIPAP,SpriteLink/NIPAP,SpriteLink/NIPAP,ettrig/NIPAP,plajjan/NIPAP,ettrig/NIPAP,SoundGoof/NIPAP,plajjan/NIPAP,SoundGoof/NIPAP,SoundGoof/NIPAP,bbaja42/NIPAP,SoundGoof/NIPAP