set new id generator even if no migration script provided

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@16956 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/Core/Folder.py

@@ -436,10 +436,10 @@ class Folder(CopyContainer, CMFBTreeFolder, CMFHBTreeFolder, Base, FolderMixIn,
     """    
     BUNDLE_COUNT = 10
     # we may want to change all objects ids before migrating to new folder type
-    if migration_generate_id_method not in (None, ''):
     # set new id generator here so that object created while migration
     # got a right id
     self.setIdGenerator(new_generate_id_method)
+    if migration_generate_id_method not in (None, ''):
       tag = "%s/%s/migrate" %(self.getId(),migration_generate_id_method) 
       id_list  = list(self.objectIds())
       # set new id by bundle