Fix random failure in testRecycledClientUUID

Traceback (most recent call last):
  File "neo/tests/threaded/test.py", line 838, in testRecycledClientUUID
    x = client.load(ZERO_TID)
  [...]
  File "neo/tests/threaded/test.py", line 822, in notReady
    m2s.remove(delayNotifyInformation)
  File "neo/tests/threaded/__init__.py", line 482, in remove
    del self.filter_dict[filter]
KeyError: <function delayNotifyInformation at 0x7f511063a578>

neo/tests/threaded/__init__.py

@@ -482,6 +482,12 @@ class ConnectionFilter(object):
                 del self.filter_dict[filter]
             self._retry()
 
+    def discard(self, *filters):
+        try:
+            self.remove(*filters)
+        except KeyError:
+            pass
+
     def __contains__(self, filter):
         return filter in self.filter_dict
 

neo/tests/threaded/test.py

@@ -819,7 +819,7 @@ class Test(NEOThreadedTest):
         def delayNotifyInformation(conn, packet):
             return isinstance(packet, Packets.NotifyNodeInformation)
         def notReady(orig, *args):
-            m2s.remove(delayNotifyInformation)
+            m2s.discard(delayNotifyInformation)
             return orig(*args)
         cluster = NEOCluster()
         try: