ryanb/cancan — pull request #955 by Peeja (2013-11-08 22:29:32+00:00)
Title: Don't load parent without id_param.

This appears to have been the intention. If so, it regressed in
d5123e0eb3017de67a9e6afa45c14a5ef096f2a8.

Without this, I'm not sure how shallow routes can work, so I'm assuming
this was a bug.