MySQL PID not found?

I have been trying to create a three-node percona cluster. The problem is, I am getting this MySQL PID not found in a freshly installed server.
root@debian-s-4vcpu-8gb-sgp1-01:~# sudo service mysql status
● mysql.service - Start and stop the mysql (Percona XtraDB Cluster) daemon
Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
Active: inactive (dead) since Tue 2018-01-23 12:46:30 UTC; 3min 33s ago
Process: 5451 ExecStop=/etc/init.d/mysql stop (code=exited, status=0/SUCCESS)
Process: 4969 ExecStart=/etc/init.d/mysql start (code=exited, status=0/SUCCESS)
Process: 4893 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
Main PID: 5007 (code=exited, status=0/SUCCESS)

Jan 23 12:46:07 debian-s-4vcpu-8gb-sgp1-01 systemd[1]: Starting Start and stop the mysql (Percona XtraDB Cluster) daemon…
Jan 23 12:46:12 debian-s-4vcpu-8gb-sgp1-01 systemd[1]: Started Start and stop the mysql (Percona XtraDB Cluster) daemon.
Jan 23 12:46:15 debian-s-4vcpu-8gb-sgp1-01 systemd[1]: Stopping Start and stop the mysql (Percona XtraDB Cluster) daemon…
Jan 23 12:46:30 debian-s-4vcpu-8gb-sgp1-01 /etc/init.d/mysql[5553]: MySQL PID not found, pid_file detected/guessed: /var/run/mysqld/mysqld.pid
Jan 23 12:46:30 debian-s-4vcpu-8gb-sgp1-01 systemd[1]: Stopped Start and stop the mysql (Percona XtraDB Cluster) daemon.

This is normal. When shutting down, the script looks for the PID file to get the PID of mysqld. However, if the server has shutdown, the server will have already removed the PID file. So the script can’t find it, thus the warning.

Maybe when checking the status during shutdown, the script shouldn’t log a message about the missing PID file.