For the record, I also tested this on Ubuntu Yakkety with the version 10.0.28-0ubuntu0.16.10.1 and I get the same warning in syslog:
mysqld: 170119 9:47:47 [Warning] Failed to setup SSL mysqld: 170119 9:47:47 [Warning] SSL error: Failed to set ciphers to use It seems something with how we do " -DWITH_SSL=bundled" and YaSSL is (and maybe always was) broken.