do not test obj directly

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@16806 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ZSQLCatalog/ZSQLCatalog.py

@@ -875,7 +875,7 @@ class ZCatalog(Folder, Persistent, Implicit):
     catalog = self.getSQLCatalog(sql_catalog_id)
     if catalog is not None:
       object = catalog[uid]
-      if object:
+      if object is not None:
         return object.path
       else:
         return None