Fix a issue that BusinessTemplate wrongly removes the sub directory skins of another business template when upgrading. To fix the issue, it is stopped to remove the sub directory when the parent is removing.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@36804 20353a03-c40f-0410-a6d1-a30d3c3de9de