main.auth_named_pipe failed in buildbot with system error: 2 "No such file or directory"

main.auth_named_pipe                     w4 [ fail ]

        Test ended at 2017-12-09 13:20:41

CURRENT_TEST: main.auth_named_pipe

mysqltest: At line 20: query 'connect pipe_con,localhost,nosuchuser,,,,,PIPE' failed with wrong errno 2013: 'Lost connection to MySQL server at 'reading authorization packet', system error: 2 "No such file or directory"', instead of 1698...

The result from queries just before the failure was:

INSTALL SONAME 'auth_named_pipe';

CREATE USER 'USERNAME' IDENTIFIED WITH named_pipe;

SELECT USER(),CURRENT_USER();

USER()	CURRENT_USER()

USERNAME@localhost	USERNAME@%

DROP USER 'USERNAME';

CREATE USER nosuchuser IDENTIFIED WITH named_pipe;