*   Mute `psql` output when running rake db:schema:load.

    *Godfrey Chan*

*   Trigger a save on `has_one association=(associate)` when the associate contents have changed.

    Fix #8856.

    *Chris Thompson*

*   Abort a rake task when missing db/structure.sql like `db:schema:load` task.

    *kennyj*

Please check [4-0-stable](https://github.com/rails/rails/blob/4-0-stable/activerecord/CHANGELOG.md) for previous changes.
