consensus: take payload hash based on data

Fix 857ced82.

pkg/consensus/consensus.go

@@ -167,6 +167,7 @@ var (
 func NewPayload(m netmode.Magic) *Payload {
 	return &Payload{
 		network: m,
+		message: new(message),
 	}
 }
 

pkg/consensus/payload.go

@@ -171,7 +171,7 @@ func (p *Payload) EncodeBinaryUnsigned(w *io.BinWriter) {
 	w.WriteU32LE(p.height)
 	w.WriteU16LE(p.validatorIndex)
 
-	if p.message != nil {
+	if p.data == nil {
 		ww := io.NewBufBinWriter()
 		p.message.EncodeBinary(ww.BinWriter)
 		p.data = ww.Bytes()