That flag is added by us because we're configuring Forever for improving the process lifecycle management (start/stop/restart).
That means everything in stdout is getting added to "parse.log". If you wanted to rotate that log you could always install Logrotate. A sample configuration file could look like this:
Unfortunately we don't include Logrotate in our Parse solution. I have created an internal task for adding this feature, but I cannot give an estimate for when it would be released.