Added enable_extension! to helper
Do not mark object as persisted after an association is saved

Callback order in Active Record objects are important. Users should not
define callbacks before the association definition or surprising
behaviours like the described at #3798 will happen. This callback order
dependency is documented at https://github.com/rails/rails/blob/31bfcdc77ca0d8cec9b5fe513bdc6f05814dd4f1/activerecord/lib/active_record/associations.rb#L1222-1227.

This reverts #15728.

Fixes #16620.
Remove CHANGELOG entry [ci skip]
Merge pull request #16114 from seuros/test_clean

[Postgresql tests] Added enable_extension! to helper
Add TODO to release the gems before the next Rails release
Use the released jquery-rails gem
Dependencies: bump to jquery-rails 4.0.0.beta2
fix the undefined method content_tag #15245
not required include ActionView::Helpers::TagHelper in test as well
Deprecate implicit AD::Response splatting and Array conversion
Merge pull request #16822 from jeremy/deprecate-problematic-implicit-response-splatting

Deprecate implicit AD::Response splatting and Array conversion
Merge pull request #16824 from rajcybage/action_view_content_tag

fix the undefined method content_tag #15245
Dynamically modified schema and association would not be correctly reset

This fixes <"SQLite3::SQLException: no such column: legacy_things.person_id: SELECT \"legacy_things\".* FROM \"legacy_things\" WHERE \"legacy_things\".\"person_id\" = ?">
in OptimisticLockingTest#test_lock_destroy
disable migrations logging while running test cases for AR schema tests
Add support for Rack::ContentLength middelware
Fix query with nested array in Active Record

`User.where(id: [[1,2],3])` was equal to `User.where(id:[1, 2, 3])`
in Rails 4.1.x but because of some refactoring in Arel this stopped
working in 4.2.0. This fixes it in Rails.

[Dan Olson & Cristian Bica]
Merge pull request #16793 from javan/comply_with_rack_content_length_middleware

Add support for Rack::ContentLength middelware
Ignore segfault build errors with 2.0.0 + mysql-ruby

Continuation of c9a43126c5e2c608ab3ff1be994bce69e815a144

:cry:
[guides] Use `match ..., via: :all` in the custom exceptions app [ci skip]

Using `get` results in an unexpected error page(returning empty body) for requests of other HTTP mehtods other than GET. Use `match ..., via:
:all` so the exceptions app can be more stable.
Merge pull request #16832 from yuki24/use-match-via-all-in-custom-exceptions-app

[guides] Use `match ..., via: :all` in the custom exceptions app [ci skip]
[ci skip] Fix some typos, normalize sentence.

Follow up of #16722.

https://github.com/rails/rails/pull/16722

also normalize all instance gained methods’ sentence.