Bug 1473636: raise errors in cancel-all action; r=tomprince

This changes

  File "/builds/worker/checkouts/gecko/taskcluster/taskgraph/actions/cancel_all.py", line 30, in list_group
    for task in [t['status'] for t in response['tasks']]:
KeyError: u'tasks'

Into a more understandable error (404, in this case).

MozReview-Commit-ID: 5XnFyxIdRfo

--HG--
extra : rebase_source : 797a3117d3246c962f30980c1658fde3bd366135

taskcluster/taskgraph/actions/cancel_all.py

@@ -26,6 +26,7 @@ def list_group(task_group_id, session):
     while True:
         url = base_url.format('task-group/{}/list'.format(task_group_id))
         response = session.get(url, stream=True, params=params)
+        response.raise_for_status()
         response = response.json()
         for task in [t['status'] for t in response['tasks']]:
             if task['state'] in ['running', 'pending', 'unscheduled']: