pt-show-grants does not support IDENTIFIED WITH for authentication plugins

mysql> CREATE USER test_user IDENTIFIED WITH auth_pam AS 'mysql';
Query OK, 0 rows affected (0.00 sec)

mysql> GRANT ALL ON test.* TO test_user;
Query OK, 0 rows affected (0.02 sec)

The information about the authentication plugin is missing from the output.

$ pt-show-grants -uroot --ask | grep test_user
-- Grants for 'test_user'@'%'
GRANT ALL PRIVILEGES ON `test`.* TO 'test_user'@'%';
GRANT USAGE ON *.* TO 'test_user'@'%';

mysql> SELECT * FROM mysql.user WHERE User='test_user'\G
*************************** 1. row ***************************
                  Host: %
                  User: test_user
              Password:
           Select_priv: N
           Insert_priv: N
           Update_priv: N
           Delete_priv: N
           Create_priv: N
             Drop_priv: N
           Reload_priv: N
         Shutdown_priv: N
          Process_priv: N
             File_priv: N
            Grant_priv: N
       References_priv: N
            Index_priv: N
            Alter_priv: N
          Show_db_priv: N
            Super_priv: N
 Create_tmp_table_priv: N
      Lock_tables_priv: N
          Execute_priv: N
       Repl_slave_priv: N
      Repl_client_priv: N
      Create_view_priv: N
        Show_view_priv: N
   Create_routine_priv: N
    Alter_routine_priv: N
      Create_user_priv: N
            Event_priv: N
          Trigger_priv: N
Create_tablespace_priv: N
              ssl_type:
            ssl_cipher:
           x509_issuer:
          x509_subject:
         max_questions: 0
           max_updates: 0
       max_connections: 0
  max_user_connections: 0
                plugin: auth_pam
 authentication_string: mysql
1 row in set (0.00 sec)