rails/rails — pull request #11952 by lmarcetic (2013-08-21 03:01:16+00:00)
Title: Remove set_primary_key, replace with primary_key=

First deprecated, now removed: https://github.com/rails/rails/commit/9add7608f1acaa68b025470e7a38901d7e6161ca#activerecord/lib/active_record/attribute_methods/primary_key.rb