Fix boolean condition is NodeManager.clear()

git-svn-id: https://svn.erp5.org/repos/neo/branches/prototype3@1187 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/node.py

@@ -209,7 +209,7 @@ class NodeManager(object):
     
     def clear(self, filter=None):
         for node in self.getNodeList():
-            if filter is not None and filter(node):
+            if filter is None or filter(node):
                 self.remove(node)
 
     def update(self, node_list):