title: Example DAG gets stuck in "running" state indefinitely
body: <p>In my first foray into airflow, I am trying to run one of the example DAGS that comes with the installation.  This is v.1.8.0.  Here are my steps:</p>
  
  <pre><code>$ airflow trigger_dag example_bash_operator
  [2017-04-19 15:32:38,391] {__init__.py:57} INFO - Using executor SequentialExecutor
  [2017-04-19 15:32:38,676] {models.py:167} INFO - Filling up the DagBag from /Users/gbenison/software/kludge/airflow/dags
  [2017-04-19 15:32:38,947] {cli.py:185} INFO - Created &lt;DagRun example_bash_operator @ 2017-04-19 15:32:38: manual__2017-04-19T15:32:38, externally triggered: True&gt;
  $ airflow dag_state example_bash_operator '2017-04-19 15:32:38'
  [2017-04-19 15:33:12,918] {__init__.py:57} INFO - Using executor SequentialExecutor
  [2017-04-19 15:33:13,229] {models.py:167} INFO - Filling up the DagBag from /Users/gbenison/software/kludge/airflow/dags
  running
  </code></pre>
  
  <p>The dag state remains "running" for a long time (at least 20 minutes by now), although from a quick inspection of this task it should take a matter of seconds.  How can I troubleshoot this?  How can I see which step it is stuck on?</p>