cfn.getTemplate may return YAML instead of JSON

[rreusser]

It appears that cfn.getTemplate may return JSON or YAML, but L126 in lookup.js presumes that it is necessarily JSON. I am trying to deploy a particular stack, but the content is YAML and so it throws an error when parsed as JSON. I'm not sure what dictates which the content is, or if there's a way to determine which it is, except to try one and then try the other if that fails.

https://github.com/mapbox/cfn-config/blob/2c6b4b09768e3d85bfe8689eb136d1dbd0c9865b/lib/lookup.js#L126

See: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/template-anatomy.html

[rreusser]

Oh, this is addressed by #184. Perhaps the real issue is that even though YAML should correctly be forbidden, somehow YAML made its way into a template in the first place and now cannot directly be updated.