Validation problem in term_translation_update_many

If no data is given then num is not defined here:
https://github.com/okfn/ckan/blob/master/ckan/logic/action/update.py#L776

This should be caught here, but for some reason we are also checking to see if data_dict is a list:
https://github.com/okfn/ckan/blob/master/ckan/logic/action/update.py#L768