rails/rails — pull request #4783 by gregolsen (2012-01-31 10:01:03+00:00)
Title: ids_reader method fixed, test added to has_many association (for PostgreSQL)

See this issue #4758, and this PR #4738 to follow the discussion.
`uniq` was added to `ids_reader` in 109db5a, but, due to SELECT DISTINCT limitation on PostgreSQL, this cause an error.
I've added a test that was failing on PostgreSQL and fixed `ids_reader` by removing `uniq`.