just revert the r27722 because that commit breaks backword compatibility.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@27767 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ZSQLCatalog/SQLCatalog.py

@@ -2023,7 +2023,6 @@ class Catalog(Folder,
         value = dict(value)
       if ignore_empty_string and (
           value == ''
-          or value is None
           or (isinstance(value, (list, tuple)) and len(value) == 0)
           or (isinstance(value, dict) and (
             'query' not in value

product/ZSQLCatalog/tests/testSQLCatalog.py

@@ -277,8 +277,6 @@ class TestSQLCatalog(unittest.TestCase):
                    ReferenceQuery(operator='<', date=DateTime('2008/02/02 10:10:11 UTC'))
                  , operator='and'), operator='and'),
                  {column: '2008/02/02 10:10:10 UTC'})
-    self.catalog(ReferenceQuery(operator='and', date=None),
-                 {column: None})
         
   def test_DateTimeKey(self):
     self._testDateTimeKey('date')