Arvados

I have not completely confirmed this yet, but I think crunch-job has a bug in which it can miss the last chunk of output from a job if the job writes the output between the time readfrompipes() finishes reading that job and when reapchildren() checks to see if it has exited (and it has).

The fix should probably be to have reapchildren flush the output of the job and handle it in the same manner as readfrompipes (it would probably be good to split that functionality out to facilitate doing that - perhaps into `readfrompipe`).