unit.conc_connection fails in test_conc748

unit.conc_connection fails in buildbot for amd64-rhel-7
https://buildbot.mariadb.org/#/builders/222/builds/36856/steps/6/logs/stdio

1. Connection parameters
2. Schema: test
3. Host: (null)
4. Port: 19210
5. TLS Port: 19210
6. Socket: /home/buildbot/amd64-rhel-7/build/mysql-test/var/tmp/8/mysqld.1.sock
7. Plugindir: /home/buildbot/amd64-rhel-7/build/mysql-test/var/plugins
   1..47
8. TLS server variables
9. --------------------
10. have_openssl: YES
11. have_ssl: YES
12. ssl_ca: /home/buildbot/amd64-rhel-7/build/mysql-test/std_data/cacert.pem
13. ssl_capath:
14. ssl_cert: /home/buildbot/amd64-rhel-7/build/mysql-test/std_data/server-cert.pem
15. ssl_cipher:
16. ssl_crl:
17. ssl_crlpath:
18. ssl_key: /home/buildbot/amd64-rhel-7/build/mysql-test/std_data/server-key.pem
19. version_ssl_library: OpenSSL 1.0.2k-fips 26 Jan 2017
20. Cipher in use: DHE-RSA-AES256-GCM-SHA384
21. --------------------
22. Testing against MySQL Server 10.11.14-MariaDB-log
23. Host: Localhost via UNIX socket
24. Client library: 3.3.17
    ok 1 - test_conc589
25. error: TLS/SSL error: no cipher match
26. error: TLS/SSL error: no cipher match
    not ok 2 - test_conc748

Could be a configuration error on the buildbot but should be fixed so that we can keep buildbot green.