If my play server crashes, the pid file is not removed when I execute "play stop" ("Play was not running (Process id 5642 not found)").
When I then go and try a "play start", I get the error message "Oops. /mnt/app/yosoft/thor/server is already started! (or delete /path/to/server.pid)".
At least the stop script should remove the pid file if the process doesn't exist; ideally both commands would.