TrashTool: fail if backup object container already exist

This is not supposed to happen and can hide errors.

product/ERP5/Tool/TrashTool.py

@@ -80,9 +80,6 @@ class TrashTool(BaseTool):
       # backup the object
       # here we choose export/import to copy because cut/paste
       # do too many things and check for what we want to do
-      obj = None
-      if object_id not in backup_object_container.objectIds():
-        # export object
       object_path = container_path + [object_id]
       obj = self.unrestrictedTraverse(object_path, None)
       if obj is not None: