Launch: Help us enforce maker/checker process

Currently, the following roles are available:

• develop
• approve
• publish

I want to be able to stop people approving code that they have developed themselves.  However, our team is not big enough that we can afford to have mutually exclusive groups of developers and testers.  Therefore, I have to give 'develop' and 'approve' rights to everyone, which mean users can effectively mark their own homework.

What I would like is an additional 'approve' permission which only allows a user to 'approve' libraries submitted for approval by other users  i.e. they can 'approve' other peoples code for publishing, but not their own.