if getPortalType() is missing, that can happen at for example <Folder at xxx used for /erp5/web_site_module/yyy>, return None instead of raising an exception.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@29877 20353a03-c40f-0410-a6d1-a30d3c3de9de