Fix participation lease removal for wrong network

When manifest changes, depending on the timing it is possible for newly
generated valid leases to get removed if the sign message loop attempts
to sign messages that are as a result of progressing previous network.

Here is an example scenario in a specific order that was causing itests
to fail:
 * participants get a lease for network A up to instance 5
 * network A progresses to instance 6
 * manifest changes the network name to B
 * participants get a new lease for network B up to instance 5
 * sign loop receives a message from network A, instance 6
 * `getParticipantsByInstance` lazily removes leases since it only
   checks the instance.
 * the node ends up with no participants, and stuck.

To fix this:
 1) check if participants asked for are within the current network, and
    if not refuse to participate.
 2) check network name, as well as instance, to lazily remove expired
    leases.

Author: masih

chain/lf3/f3.go

@@ -155,7 +155,7 @@ func (fff *F3) runSigningLoop(ctx context.Context) {
 			clear(alreadyParticipated)
 		}
 
-		participants := fff.leaser.getParticipantsByInstance(mb.Payload.Instance)
+		participants := fff.leaser.getParticipantsByInstance(mb.NetworkName, mb.Payload.Instance)
 		for _, id := range participants {
 			if _, ok := alreadyParticipated[id]; ok {
 				continue

chain/lf3/participation_lease.go

@@ -112,15 +112,26 @@ func (l *leaser) participate(ticket api.F3ParticipationTicket) (api.F3Participat
 	return newLease, nil
 }
 
-func (l *leaser) getParticipantsByInstance(instance uint64) []uint64 {
+func (l *leaser) getParticipantsByInstance(network gpbft.NetworkName, instance uint64) []uint64 {
 	l.mutex.Lock()
 	defer l.mutex.Unlock()
+	currentManifest, _ := l.status()
+	currentNetwork := currentManifest.NetworkName
+	if currentNetwork != network {
+		log.Warnf("no participants for network: current network (%s) does not match requested network (%s) at instance %d", currentNetwork, network, instance)
+		return nil
+	}
 	var participants []uint64
 	for id, lease := range l.leases {
-		if instance > lease.ToInstance() {
+		if currentNetwork != lease.Network {
+			// Lazily delete any lease that does not belong to network, likely acquired from
+			// prior manifests.
+			delete(l.leases, id)
+			log.Warnf("lost F3 participation lease for miner %d at instance %d due to network mismatch: %s != %s", id, instance, currentNetwork, lease.Network)
+		} else if instance > lease.ToInstance() {
 			// Lazily delete the expired leases.
 			delete(l.leases, id)
-			log.Warnf("lost F3 participation lease for miner %d", id)
+			log.Warnf("lost F3 participation lease for miner %d due to instance (%d) > lease to instance (%d)", id, instance, lease.ToInstance())
 		} else {
 			participants = append(participants, id)
 		}