galera_sr.mysql-wsrep-features#165 test test fails sporadically in Codership jenkins testing.
The failure is due to debug sync point wait timeout. The test itself has two sequential SQL statements being asynchronously sent for execution (--send), without later checking the progress of the execution, and this is likely the cause for the failures, The failing test case output looks like the following:

CURRENT_TEST: galera_sr.mysql-wsrep-features#165
— /home/jenkins/workspace/mtr-galera-4.x-mariadb-10.4-master/mysql-wsrep/mysql-test/suite/galera_sr/r/mysql-wsrep-features#165.result 2022-06-14 00:02:36.743397840 +0200
+++ /home/jenkins/workspace/mtr-galera-4.x-mariadb-10.4-master/mysql-wsrep/mysql-test/suite/galera_sr/r/mysql-wsrep-features#165.reject 2022-06-14 00:39:22.078665000 +0200
@@ -366,6 +366,8 @@
UPDATE t1 SET f2 = 'b' WHERE f1 = 1;
connection node_1;
SET DEBUG_SYNC = 'now WAIT_FOR wait';
+Warnings:
+Warning 1639 debug sync point wait timed out
connection node_1;
SET DEBUG_SYNC = 'now SIGNAL continue';
connection node_1c;

mysqltest: Result length mismatch

The problem persists in 10.4 and later versions