gearman responds back with a `NO_JOB`:
```
  DEBUG 2014-05-13 01:20:53.349603 [  proc ] PACKET COMMAND: GEARMAN_GRAB_JOB -> libgearman-server/server.cc:119
  DEBUG 2014-05-13 01:20:53.349640 [     1 ] Received RUN wakeup event -> libgearman-server/gearmand_thread.cc:624
  DEBUG 2014-05-13 01:20:53.349653 [     1 ] GEAR NO_JOB -> libgearman-server/plugins/protocol/gear/protocol.cc:316
  DEBUG 2014-05-13 01:20:53.349677 [     1 ] send() 12 bytes to peer -> libgearman-server/io.cc:387
  DEBUG 2014-05-13 01:20:53.349689 [     1 ] Sent NO_JOB -> libgearman-server/thread.cc:356
```