ministryofjustice/sensu-formula — pull request #30 by mikepea (2014-08-27 14:37:36+00:00)
Title: Handle the 'no roles defined' case.

This prevents a failure when a server has no defined roles grain.

Previously, failed with:

```
Comment: Unable to manage file: Jinja error: 'NoneType' object is not iterable
Traceback (most recent call last):
File "/usr/lib/pymodules/python2.7/salt/utils/templates.py", line 263, in render_jinja_tmpl
output = jinja_env.from_string(tmplstr).render(**unicode_context)
File "/usr/lib/python2.7/dist-packages/jinja2/environment.py", line 894, in render
return self.environment.handle_exception(exc_info, True)
File "