rpl.password_expiration fails: unexpected Note 4227 "Dropped users 'repl_user'@'%' have active connections" after DROP USER

rpl.password_expiration fails on 12.3 with a result mismatch: DROP USER 'repl_user' returns an unexpected Note 4227 (ER_ACTIVE_CONNECTIONS_FOR_USER_TO_DROP).

Build Run Info

Failure text

rpl.password_expiration 'mix'            w12 [ fail ]

        Test ended at 2026-10-08 17:00:55

CURRENT_TEST: rpl.password_expiration

--- /home/buildbot/s390x-sles-1507/build/mysql-test/suite/rpl/r/password_expiration.result	2026-10-08 10:18:27.000000000 +0000

+++ /home/buildbot/s390x-sles-1507/build/mysql-test/suite/rpl/r/password_expiration.reject	2026-10-08 17:00:54.973273144 +0000

@@ -20,6 +20,8 @@

 include/wait_for_slave_io_error.inc [errno=1820]

 connection master;

 DROP USER 'repl_user';

+Warnings:

+Note	4227	Dropped users 'repl_user'@'%' have active connections. Use KILL CONNECTION if they should not be used anymore.

 set global disconnect_on_expired_password=default;

 connection slave;

 include/stop_slave_sql.inc

Result length mismatch

 - saving '/home/buildbot/s390x-sles-1507/build/mysql-test/var/12/log/rpl.password_expiration-mix/' to '/home/buildbot/s390x-sles-1507/build/mysql-test/var/log/rpl.password_expiration-mix/'

Retrying test rpl.password_expiration, attempt(2/3)...

The diff is the same in the other matching run between 2026-10-02 and 2026-10-09: bb-13.2-MDEV-41202 on s390x-ubuntu-2604, 2026-10-08T01:24:54Z.

Analysis

Two distinct builders are affected, both s390x (s390x-sles-1507 and s390x-ubuntu-2604), and no other builder reported this failure between 2026-10-02 and 2026-10-09, which points at a timing dependency in the test rather than at a single builder. DROP USER raises this note when the dropped user still has a session (MDEV-35617). In the test, DROP USER 'repl_user' runs directly after include/wait_for_slave_io_error.inc (errno=1820), so the master-side session of the replication IO connection is most likely still being cleaned up when the statement executes, and the result file expects no warning. The same note failed other tests that were fixed in the test files: MDEV-39777 (--ping before DROP USER), MDEV-40275 and MDEV-40909 (--disable_warnings around DROP USER).

Created via the mtr-failure-bug skill.