Avoid creating a PersistentMapping instance to just overwrite it at function end.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@18544 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/XMLMatrix.py

@@ -191,12 +191,6 @@ class XMLMatrix(Folder):
       if current_range == list(kw): # kw is a tuple
         return
 
-      # We must make sure the base_id exists
-      # in the event of a matrix creation for example
-      if not self.index.has_key(base_id):
-        # Create an index for this base_id
-        self.index[base_id] = PersistentMapping()
-
       # Recreate a new index for the new range defined in *kw
       i = 0
       for index_ids in kw:
@@ -207,6 +201,7 @@ class XMLMatrix(Folder):
           j += 1
         i += 1
 
+      if self.index.has_key(base_id):
         # Look at each dimension i of the previous index
         for i in self.index[base_id].keys():
           movement[i] = {}