Add a warning comment about default method parameter.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@8366 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/RoleProviderBase.py

@@ -90,6 +90,7 @@ class RoleProviderBase:
                  , condition
                  , category
                  , base_category_script
+                 # XXX Default value is a tuple, but a string is required
                  , base_category=()
                  , REQUEST=None
                  ):