ERP5VCS: fix SVN BT export when a top-level folder is removed

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@44038 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5VCS/Subversion.py

@@ -357,6 +357,7 @@ class BusinessTemplateWorkingCopy(BusinessTemplateFolder):
     self.versioned_dict = dict((x.getPath(), x) for x in self.client.status('.')
       if str(x.getTextStatus()) not in ('ignored', 'unversioned'))
     del self.versioned_dict['.']
+    self.versioned_dict[''] = None
     self.added_set = set()
 
     # Walk current tree