it is not a problem to cache None

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@42653 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/tests/ERP5TypeTestCase.py

@@ -1312,7 +1312,8 @@ def fortify():
   CacheEntry__init__ = CacheEntry.__init__
   def __init__(self, value, *args, **kw):
     # this will raise TypeError if you try to cache a persistent object
-    dumps(value)
+    if value is not None:
+      dumps(value)
     CacheEntry__init__(self, value, *args, **kw)
   CacheEntry.__init__ = __init__
   # randomize priorities of activities in a deterministic way