row is by default an empty list, not a None value, so do the rigth comparison

git-svn-id: https://svn.erp5.org/repos/neo/branches/prototype3@249 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/pt.py

@@ -114,14 +114,13 @@ class PartitionTable(object):
     def setCell(self, offset, node, state):        
         if state == DISCARDED_STATE:
             return self.removeCell(offset, node)
-
         if node.getState() in (BROKEN_STATE, DOWN_STATE):
             return
 
         row = self.partition_list[offset]
-        if row is None:
+        if len(row) == 0:
             # Create a new row.
-            row = [Cell(node, state)]
+            row = [Cell(node, state),]
             if state != FEEDING_STATE:
                 self.count_dict[node] = self.count_dict.get(node, 0) + 1
             self.partition_list[offset] = row