edx/edx-platform — pull request #4118 by jimabramson (2014-06-16 20:19:50+00:00)
Title: bugfix: avoid side-effects when overriding User.default_retrieve_params

Since c2ebfde, cc.User was prone to intermittent KeyErrors on 'upvoted_ids' due to a class default being modified.

@gwprice