div for group(s) in profile block doesn't have id for class

When a profile appears within another page (like a contribution page) and has a group checkbox item, the class for the div holding the group checkbox is "-section". All the other fields have "[field id]-section". The templates/CRM/UF/Form/Block.tpl template forms that class by using "{$form.$n.id}-section", but the $form.group array doesn't have id as a key.

Profiles in create mode do just fine (in templates/CRM/Profile/Form/Dynamic.tpl): they simply use {$n}, and that works fine. (In both cases, $n is the "name" attribute of each item in the $fields array as well as the key to the corresponding item in the $form array.)

I've attached a patch with changes to templates/CRM/UF/Form/Block.tpl so it works the same way.