Don't set tasks to done/failed twice
Don't set tasks to done/failed twice

Setting a task to done again after the process stopped will reset its
"time_finished" value on the master.

pyfarm/pyfarm-agent,guidow/pyfarm-agent,pyfarm/pyfarm-agent,guidow/pyfarm-agent,pyfarm/pyfarm-agent,guidow/pyfarm-agent