Add header back

src/neo/Network/P2P/TaskManager.cs

@@ -109,7 +109,7 @@ private void OnNewTasks(InvPayload payload)
         private void OnPersistCompleted(Block block)
         {
             foreach (var (actor, session) in sessions)
-                if (session.ReceivedBlock.Remove(block.Index))
+                if (session.ReceivedBlock.Remove(block.Index, out Block receivedBlock) && block.Hash == receivedBlock.Hash)
                     RequestTasks(actor, session);
         }