The `recv_pkt_region` is set when processing a flood packet in `filterRecvFloodPacket`
but direct/non-flood packets would never pass through that function, so the pointer was
not cleared for them.
`sendFloodReply` would then later use it blindly, which meant that the response would
either inherit the region from the last flood packet, or refer to a non-initialised pointer
if no region floods had been received yet.
