ER_UNKNOWN_ERROR "Commands out of sync" on INFORMATION_SCHEMA.TABLES when running MTR with --cursor-protocol

SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA='mysql';

$ ./mtr mytest --cursor-protocol

Logging: ./mtr  mytest --cursor-protocol

VS config:

vardir: /test/mtest/MDEV-31342/MD160926-mariadb-13.1.0-linux-x86_64-opt/mariadb-test/var

Checking leftover processes...

Removing old var directory...

Creating var directory '/test/mtest/MDEV-31342/MD160926-mariadb-13.1.0-linux-x86_64-opt/mariadb-test/var'...

Checking supported features...

MariaDB Version 13.1.0-MariaDB

 - SSL connections supported

 - binaries built with wsrep patch

Collecting tests...

Installing system database...

==============================================================================

TEST                                      RESULT   TIME (ms) or COMMENT

--------------------------------------------------------------------------

worker[01] Using MTR_BUILD_THREAD 300, with reserved ports 19000..19029

SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA='mysql';

main.mytest                              [ fail ]

        Test ended at 2026-09-18 10:28:38

CURRENT_TEST: main.mytest

mysqltest: At line 1: query 'SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA='mysql'' failed: <Unknown> (2014): Commands out of sync; you can't run this command now