maxscale doesn't cleanup pid file on startup error

$ ls -la | grep pid

$ maxscale

* Error: Failed to start all MaxScale services. Exiting.

$ cat s1-2.1.6/log/maxscale.log | grep -i error 

2017-08-24 08:17:29   error  : [mysqlmon] No Master can be determined

2017-08-24 08:17:30   error  : [MySQLAuth] [Read-Service] Failed to connect to server 'm1' ([127.0.0.1]:3307) when checking authentication user credentials and permissions: 1045 Access denied for user 'galera'@'localhost' (using password: YES)

2017-08-24 08:17:30   error  : [MySQLAuth] [Read-Service] Failed to connect to server 'm2' ([127.0.0.1]:3308) when checking authentication user credentials and permissions: 1045 Access denied for user 'galera'@'localhost' (using password: YES)

2017-08-24 08:17:30   error  : [Read-Service] Fatal error when loading users for listener 'Read Listener', service is not started.

2017-08-24 08:17:30   error  : [MySQLAuth] [Read-Service] Failed to connect to server 'm1' ([127.0.0.1]:3307) when checking authentication user credentials and permissions: 1045 Access denied for user 'galera'@'localhost' (using password: YES)

2017-08-24 08:17:30   error  : [MySQLAuth] [Read-Service] Failed to connect to server 'm2' ([127.0.0.1]:3308) when checking authentication user credentials and permissions: 1045 Access denied for user 'galera'@'localhost' (using password: YES)

2017-08-24 08:17:30   error  : [Read-Service] Fatal error when loading users for listener 'Read Listener', service is not started.

2017-08-24 08:17:30   error  : Failed to start service 'Read-Service'.

2017-08-24 08:17:30   error  : Failed to start all MaxScale services. Exiting.

$ ls -la | grep pid

-rwxr-xr-x  1 buildbot buildbot    5 Aug 24 08:17 maxscale.pid

$ ps auxwww | grep $(cat maxscale.pid)

buildbot 21579  0.0  0.0  12728  2180 pts/0    R+   08:21   0:00 grep 21540

$ pidof maxscale

$ echo $?

1