dhcp: always send parameter_request_list. Fixes #445.

src/dhcp/clientv4.rs

@@ -288,7 +288,7 @@ impl Client {
             requested_ip: None,
             client_identifier: Some(mac),
             server_identifier: None,
-            parameter_request_list: None,
+            parameter_request_list: Some(PARAMETER_REQUEST_LIST),
             max_size: Some(raw_socket.payload_recv_capacity() as u16),
             lease_duration: None,
             dns_servers: None,
@@ -321,7 +321,6 @@ impl Client {
                 dhcp_repr.broadcast = false;
                 dhcp_repr.requested_ip = Some(r_state.requested_ip);
                 dhcp_repr.server_identifier = Some(r_state.server_identifier);
-                dhcp_repr.parameter_request_list = Some(PARAMETER_REQUEST_LIST);
                 net_trace!("DHCP send request to {} = {:?}", endpoint, dhcp_repr);
                 send_packet(iface, endpoint, dhcp_repr)
             }