confusing error message for SET ROLE INVALID

MariaDB [(none)]> select version();

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

| version()       |

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

| 10.2.34-MariaDB |

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

1 row in set (0.00 sec)

MariaDB [(none)]> drop role mariadb_dump_import_role;

Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> Bye

[dan@linux build-mariadb-server-10.2]$ mc -u superbob -p < /dev/shm/var_auto_Ptio/tmp/dump1.sql

Enter password: 

ERROR 1193 (HY000) at line 5: Unknown system variable 'ROLE'

[dan@linux build-mariadb-server-10.2]$ cat /dev/shm/var_auto_Ptio/tmp/dump1.sql

SELECT COALESCE(QUOTE(CURRENT_ROLE()),'NONE') into @current_role;

CREATE ROLE mariadb_dump_import_role;

SET ROLE mariadb_dump_import_role;

SET ROLE NONE;

EXECUTE IMMEDIATE CONCAT('SET ROLE ', @current_role);

[dan@linux build-mariadb-server-10.2]$ mc -u superbob

Welcome to the MariaDB monitor.  Commands end with ; or \g.

Your MariaDB connection id is 19

Server version: 10.2.34-MariaDB Source distribution

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> 

MariaDB [(none)]> set @current_role='mariadb_dump_import_role';

Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> EXECUTE IMMEDIATE CONCAT('SET ROLE ', @current_role);

Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> select current_role();

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

| current_role()           |

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

| mariadb_dump_import_role |

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

1 row in set (0.00 sec)