FSNamesystem.appendFile() try to remove block from replication queue, but It may not work

the process appendFile() seems to remove block from replication queue, but It may not work , with the code:

FSNamesystem.appendFile()
{

...
// Remove block from replication queue.
updateNeededReplications(last, 0, 0); // last is the block appending
...
}

UnderReplicatedBlocks.updateNeededReplications(last, 0, 0)

{ NumberReplicas repl = countNodes(last); int curExpectedReplicas = getReplication(last); neededReplications.update(last, repl.liveReplicas(), repl.decommissionedReplicas(), curExpectedReplicas, 0, 0); }

UnderReplicatedBlocks.update(Block block, int curReplicas,
int decommissionedReplicas,
int curExpectedReplicas,
int curReplicasDelta, int expectedReplicasDelta)
{
//while the curReplicasDelta & expectedReplicasDelta are all be 0,
//the oldReplicas and oldExpectedReplicas while be the same
// then the curPri == oldPri

int oldReplicas = curReplicas-curReplicasDelta;
int oldExpectedReplicas = curExpectedReplicas-expectedReplicasDelta;
int curPri = getPriority(block, curReplicas, decommissionedReplicas, curExpectedReplicas);
int oldPri = getPriority(block, oldReplicas, decommissionedReplicas, oldExpectedReplicas);

// the if condition may get false , coz oldPri == curPri
// this will never remove(), and it may call the add()
if(oldPri != LEVEL && oldPri != curPri)

{ remove(block, oldPri); }

if(curPri != LEVEL && priorityQueues.get(curPri).add(block))

{ ... //log() }

}