dhruvaray/backbone-associations — pull request #50 by monokrome (2013-07-09 04:42:23+00:00)
Title: Provide the relation itself to relatedModel function handlers.

For one example of where this is useful, please see:

https://gist.github.com/monokrome/5954751

This happens in any case where a function is abstracted out and the relation data can not be assumed, so I would think that it would be a fairly common issue.