ALTER TABLE IF EXISTS non_exists results in warning with Level "Error"

MariaDB [test]>  ALTER TABLE IF EXISTS non_exists FORCE;

Query OK, 0 rows affected, 1 warning (7.918 sec)

MariaDB [test]> show warnings;

+-------+------+---------------------------------------+

| Level | Code | Message                               |

+-------+------+---------------------------------------+

| Error | 1146 | Table 'test.non_exists' doesn't exist |

+-------+------+---------------------------------------+

1 row in set (0.000 sec)

MariaDB [test]> show tables;

+----------------+

| Tables_in_test |

+----------------+

| v2             |

+----------------+

1 row in set (0.001 sec)

MariaDB [test]> create table if not exists v2 (yo int);

Query OK, 0 rows affected, 1 warning (0.000 sec)

MariaDB [test]> show warnings;

+-------+------+---------------------------+

| Level | Code | Message                   |

+-------+------+---------------------------+

| Note  | 1050 | Table 'v2' already exists |

+-------+------+--------------------------

9645	  error= open_tables(thd, &table_list, &tables_opened, 0,

9646	                     &alter_prelocking_strategy);

9647	  thd->open_options&= ~HA_OPEN_FOR_ALTER;

9648	

9649	  if (unlikely(error))

9650	  {

9651	    if (if_exists)

(gdb) list

9652	    {

9653	      int tmp_errno= thd->get_stmt_da()->sql_errno();

9654	      if (tmp_errno == ER_NO_SUCH_TABLE)

9655	      {

9656	        /*

9657	          ALTER TABLE IF EXISTS was used on not existing table

9658	          We have to log the query on a slave as the table may be a shared one

9659	          from the master and we need to ensure that the next slave can see

9660	          the statement as this slave may not have the table shared

9661	        */

(gdb) list

9662	        thd->clear_error();

9663	        DBUG_RETURN(log_and_ok(thd));

9664	      }

    if (if_exists())

      thd->push_internal_handler(&no_such_table_handler);

    error= open_and_lock_tables(thd, first_table, FALSE, 0);

    if (if_exists())

    {

      trapped_errors= no_such_table_handler.safely_trapped_errors();

      thd->pop_internal_handler();

    }