Unit tests: do not open Data.fs in write mode if not needed

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@36454 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/tests/custom_zodb.py

@@ -108,7 +108,7 @@ while not zeo_client:
   if save:
     Storage = FileStorage(data_fs_path)
   elif load:
-    Storage = DemoStorage(base=FileStorage(data_fs_path))
+    Storage = DemoStorage(base=FileStorage(data_fs_path, read_only=True))
   else:
     Storage = DemoStorage()
   break