use getUserName() explicitly instead of __str__().

product/ERP5Security/ERP5UserManager.py

@@ -288,8 +288,8 @@ class ERP5UserManager(BasePlugin):
       return []
     if isinstance(login, list):
       login = tuple(login)
-    elif not isinstance(login, tuple):
-      login = str(login)
+    elif not isinstance(login, (tuple, str)):
+      login = login.getUserName()
     try:
       return getUserByLogin(self.getPortalObject(), login, exact_match)
     except ConflictError:

product/ERP5Type/UnrestrictedMethod.py

@@ -105,9 +105,9 @@ def super_user():
         uf = getSite().acl_users
       role_list = uf.valid_roles()
       if anonymous:
-        # If the user is anonymous, use the id of the system user,
+        # If the user is anonymous, use the user name of the system user,
         # so that it would not be treated as an unauthorized user.
-        user_id = str(system)
+        user_id = system.getUserName()
       else:
         user_id = user.getId()
       super_user = PrivilegedUser(user_id, None,