hydra-queue-runner: Don't unlock builds we just started

This happens if the previous iteration took more than 60 seconds. Then the queue runner may think that builds failed to start properly and unlock them, e.g.

build 5264936 pid 19248 died, unlocking build 5264951 pid 19248 died, unlocking build 5257073 pid 19248 died, unlocking …

Created by  Eelco Dolstra  on June 7, 2013
I7UELKBVDQOL47ZCBLDOLP3KUEFDNCWUPL4K4IG6FDRVVHOBWQ4QC
Change contents