Merge pull request #546 from dachary/wip-stop-worker

add stop_worker: as a mean to shutdown the worker

diff --cc teuthology/worker.py
index cc6eb7b1d7691fb6a00bcfeb76daf16995a0c735,200f34395a803c3755b7ff864fb96f53485c42c3..843df9a3ef4205b82c8459db4df4f3fc64f7b97b
--- 1/teuthology/worker.py
--- 2/teuthology/worker.py
+++ b/teuthology/worker.py
@@@ -79,11 -79,11 +79,12 @@@ def main(ctx)
      beanstalk.watch_tube(connection, ctx.tube)
      result_proc = None
  
 -    fetch_teuthology('master')
 +    if teuth_config.teuthology_path is None:
 +        fetch_teuthology('master')
      fetch_qa_suite('master')
  
-     while True:
+     keep_running = True
+     while keep_running:
          # Check to see if we have a teuthology-results process hanging around
          # and if so, read its return code so that it can exit.
          if result_proc is not None and result_proc.poll() is not None: