Submitted custom data values not reloaded on form when validation fails

A regression due to CRM-16676 (I think) for some components other than contacts – activities and events are what I've tested but as I read the this patch, others might be affected as well – where custom data sets include a required field or some other form of validation, e.g. integer, custom validation rules, etc. If a user fails the validation, when the page reloads with the validation failure message, none of the submitted values for any custom data are reloaded on the page.