applied patch for forked process status

Hi Diego,

as promised earlier today, here is the pull request for the changes I did in order to monitor the child process status and make a non-zero exit status fail. Would be great to see this change in your repository.

In the meantime, I have switched my perl to 5.18.0 and observed 4 Tests in 02-queue.t failing approximately every 3rd run, while 5.16.3 still succeeds. Nothing serious, I hope.

Best,

Wolfgang