Hmm, yeah, maybe we should, on the other hand <https://github.com/okfn/ckan/pull/651> just nukes half of the IDatasetForm interface without bothering to deprecate stuff. So we could say fuck it and just not even call `check_data_dict()` at all anymore, or we could change #651 and make it deprecate things nicely (but given how broken and random the behaviour that #651 replaces is, that might be a pain)