Comment 1 for bug 1057471

Similar issue, layout.yaml had no 'jobs' section despite it being marked as optional in the documentation.

Stack trace from zuul dev branch:

2012-09-27 11:17:22,859 ERROR zuul.Scheduler: Exception in run handler:
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/zuul-1.0-py2.7.egg/zuul/scheduler.py", line 330, in run
    self._doPauseEvent()
  File "/usr/local/lib/python2.7/dist-packages/zuul-1.0-py2.7.egg/zuul/scheduler.py", line 294, in _doPauseEvent
    self._parseConfig(self.config.get('zuul', 'layout_config'))
  File "/usr/local/lib/python2.7/dist-packages/zuul-1.0-py2.7.egg/zuul/scheduler.py", line 105, in _parseConfig
    for config_job in data['jobs']:
TypeError: 'NoneType' object is not iterable

Same happens when key was named 'project' instead of 'projects' (aka singular vs plural form).

At startup zuul should probably run scheduler._parseConfig() and abort whenever an exception is raised.