Comment 2 for bug 1557929

I can't reproduce it:
[vagrant@t-centos7-64 ~]$ sudo systemctl start mysql

[vagrant@t-centos7-64 ~]$ sudo cat /var/log/mysqld.log |grep pass
2016-03-16T10:39:22.840738Z 1 [Note] A temporary password is generated for root@localhost: K=,+TuSId7ti

Can you check that you have "log-error=/var/log/mysqld.log" in your my.cnf [mysqld] section and then start the service. Temp password is generated on the first run after server installation.