i find a bug in using /etc/init.d/mysql script to start percona5.5.20

i recently upgrade my DB from mysql5.0.77-log to percona server 5.5.20-55,when i start percona server,it seems the script have some
problem

the mysql is running ,i open performance schema,when i restart it…

service mysql restart

MySQL (Percona Server) PID file could not be found! [FAILED]
Starting MySQL (Percona Server)…
.

ps -ef|grep mysql

root 24648 24626 0 08:35 pts/1 00:00:00 mysql
root 24836 24626 0 08:59 pts/1 00:00:00 vi mysqld-50
root 25743 1 0 10:23 pts/1 00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --pid-

file=/var/lib/mysql/mysqld.pid
mysql 26330 25743 0 10:23 pts/1 00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-

dir=/usr/lib64/mysql/plugin --user=mysql --log-error=/var/lib/mysql/err.log --pid-file=/var/lib/mysql/mysqld.pid –

socket=/var/lib/mysql/mysql.sock --port=3306
root 26471 1 0 10:39 pts/1 00:00:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --pid-

file=/var/lib/mysql/mysqld.pid
mysql 27058 26471 1 10:39 pts/1 00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-

dir=/usr/lib64/mysql/plugin --user=mysql --log-error=/var/lib/mysql/err.log --pid-file=/var/lib/mysql/mysqld.pid –

socket=/var/lib/mysql/mysql.sock --port=3306
root 27134 24626 0 10:40 pts/1 00:00:00 grep mysql