Fix 'workflow.info' command broken on workflows using signals
Fix 'workflow.info' command broken on workflows using signals

The last 'task' in the history may be a 'signal task', where contrary to
'activity tasks', the timestamp is unique. The task looks like that:

  {
    'state': u'signaled',
    'name': u'a.signal.name',
    'external_run_id': u'22YWOjwR889N6foobar',
    'timestamp': datetime.datetime(2018, 1, 22, 13, 33, 44, 732000, tzinfo=<UTC>),
    'event_id': 30,
    'input': {u'args': [], u'__propagate': True, u'kwargs': {}},
    'type': 'signal',
    'external_initiated_event_id': 29,
    'external_workflow_id': u'a_workflow_id'
  }

botify-labs/simpleflow,botify-labs/simpleflow