Program: 45812
Project: 45812
Buggy source:
private boolean checkIfJoinRequestFromAnExistingMember(JoinMessage joinMessage,Connection connection){
  Address target=joinMessage.getAddress();
  MemberImpl member=clusterService.getMember(target);
  if (member == null) {
    return checkIfUsingAnExistingMemberUuid(joinMessage);
  }
  if (joinMessage.getUuid().equals(member.getUuid())) {
    sendMasterAnswer(target);
    if (clusterService.isMaster() && !isMastershipClaimInProgress()) {
      if (logger.isFineEnabled()) {
        logger.fine(format("String_Node_Str",joinMessage));
      }
      OnJoinOp preJoinOp=preparePreJoinOps();
      OnJoinOp postJoinOp=preparePostJoinOp();
      PartitionRuntimeState partitionRuntimeState=node.getPartitionService().createPartitionState();
      Operation op=new FinalizeJoinOp(member.getUuid(),clusterService.getMembershipManager().getMembersView(),preJoinOp,postJoinOp,clusterClock.getClusterTime(),clusterService.getClusterId(),clusterClock.getClusterStartTime(),clusterStateManager.getState(),clusterService.getClusterVersion(),partitionRuntimeState,false);
      op.setCallerUuid(clusterService.getThisUuid());
      nodeEngine.getOperationService().send(op,target);
    }
    return true;
  }
  if (clusterService.isMaster() || target.equals(clusterService.getMasterAddress())) {
    String msg=format("String_Node_Str" + "String_Node_Str",member);
    logger.warning(msg);
    clusterService.suspectMember(member,msg,false);
    Connection existing=node.connectionManager.getConnection(target);
    if (existing != connection) {
      if (existing != null) {
        existing.close(msg,null);
      }
      node.connectionManager.registerConnection(target,connection);
    }
  }
  return true;
}

Fixed version (ground truth):
private boolean checkIfJoinRequestFromAnExistingMember(JoinMessage joinMessage,Connection connection){
  Address target=joinMessage.getAddress();
  MemberImpl member=clusterService.getMember(target);
  if (member == null) {
    return checkIfUsingAnExistingMemberUuid(joinMessage);
  }
  if (joinMessage.getUuid().equals(member.getUuid())) {
    sendMasterAnswer(target);
    if (clusterService.isMaster() && !isMastershipClaimInProgress()) {
      if (logger.isFineEnabled()) {
        logger.fine(format("String_Node_Str",joinMessage));
      }
      OnJoinOp preJoinOp=preparePreJoinOps();
      OnJoinOp postJoinOp=preparePostJoinOp();
      PartitionRuntimeState partitionRuntimeState=node.getPartitionService().createPartitionState();
      Operation op=new FinalizeJoinOp(member.getUuid(),clusterService.getMembershipManager().getMembersView(),preJoinOp,postJoinOp,clusterClock.getClusterTime(),clusterService.getClusterId(),clusterClock.getClusterStartTime(),clusterStateManager.getState(),clusterService.getClusterVersion(),partitionRuntimeState,false);
      op.setCallerUuid(clusterService.getThisUuid());
      invokeClusterOp(op,target);
    }
    return true;
  }
  if (clusterService.isMaster() || target.equals(clusterService.getMasterAddress())) {
    String msg=format("String_Node_Str" + "String_Node_Str",member);
    logger.warning(msg);
    clusterService.suspectMember(member,msg,false);
    Connection existing=node.connectionManager.getConnection(target);
    if (existing != connection) {
      if (existing != null) {
        existing.close(msg,null);
      }
      node.connectionManager.registerConnection(target,connection);
    }
  }
  return true;
}