test ignore_empty_string as a boolean, not an int

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@22236 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ZSQLCatalog/Query/SimpleQuery.py

@@ -211,7 +211,9 @@ class SimpleQuery(QueryMixin):
       # do not further generate sql expressions because
       # we ignore empty strings by default
       return sql_expressions
-    elif ignore_empty_string==0 and isinstance(value, basestring) and value.strip() == '':
+    elif (not ignore_empty_string) \
+        and isinstance(value, basestring) \
+        and value.strip() == '':
       # explicitly requested not to ignore empty strings
       sql_expressions = {'where_expression': "%s = ''" %key, 
                          'select_expression_list': []}