rails/rails — pull request #7925 by ernie (2012-10-12 20:23:42+00:00)
Title: Fix has_many assocation w/select load after create

Backported from master, per #7859

If you create a new record via a collection association proxy that has
not loaded its target, and which selects additional attributes through
the association, then when the proxy loads its target, it will
inadvertently trigger a deprecation notice during attribute writing when
CollectionAssociation#merge_target_lists attempts to do its thing, since
the newly loaded records will possess attributes the created record does
not.