What's the zonefile inventory vector for this peer?
    Return None if not defined

def atlas_peer_get_zonefile_inventory( peer_hostport, peer_table=None ):
    """
    What's the zonefile inventory vector for this peer?
    Return None if not defined
    """
    inv = None

    with AtlasPeerTableLocked(peer_table) as ptbl:
        if peer_hostport not in ptbl.keys():
            return None

        inv = ptbl[peer_hostport]['zonefile_inv']

    return inv