Do not try to remove '_v_catalog_schema_dict' if it does not exist (e.g. when creating a new site).

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@2838 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ZSQLCatalog/SQLCatalog.py

@@ -465,6 +465,7 @@ class Catalog(Folder, Persistent, Acquisition.Implicit, ExtensionClass.Base):
         pass
 
     # Remove the cache of catalog schema.
+    if hasattr(self, '_v_catalog_schema_dict') :
       del self._v_catalog_schema_dict
     
     self._clearSecurityCache()