Format pass on 4.2 release notes [ci skip]

*   Leave two blank lines between sections/packages for readibility.

*   Always indent bullet points with four spaces. This allows multi-paragraph
    points to align properly (see #16103), and it is the same as the format we
    already use in CHANGELOGs. Doing this consistently sets an easy precedent
    for future contributors to follow.

*   Always put the PR/commit link on its own line in the source. If the bullet
    point spans multiple paragraphs, put it on its own paragraph at the end.

[Godfrey Chan & Juanito Fatas]

1 files changed, 163 insertions, 157 deletions

diff --git a/guides/source/4_2_release_notes.md b/guides/source/4_2_release_notes.md
index 2729ca6588..12db528b91 100644
--- a/guides/source/4_2_release_notes.md
+++ b/guides/source/4_2_release_notes.md
@@ -59,31 +59,32 @@ Please refer to the [Changelog][railties] for detailed changes.
 
 ### Removals
 
-* The `rails application` command has been removed without replacement.
-  ([Pull Request](https://github.com/rails/rails/pull/11616))
+*   The `rails application` command has been removed without replacement.
+    ([Pull Request](https://github.com/rails/rails/pull/11616))
 
 ### Deprecations
 
-* Deprecated `Rails::Rack::LogTailer` without replacement.
-  ([Commit](https://github.com/rails/rails/commit/84a13e019e93efaa8994b3f8303d635a7702dbce))
+*   Deprecated `Rails::Rack::LogTailer` without replacement.
+    ([Commit](https://github.com/rails/rails/commit/84a13e019e93efaa8994b3f8303d635a7702dbce))
 
 ### Notable changes
 
-* Introduced `--skip-gems` option in the app generator to skip gems such as
-  `turbolinks` and `coffee-rails` that does not have their own specific flags.
-  ([Commit](https://github.com/rails/rails/commit/10565895805887d4faf004a6f71219da177f78b7))
+*   Introduced `--skip-gems` option in the app generator to skip gems such as
+    `turbolinks` and `coffee-rails` that does not have their own specific flags.
+    ([Commit](https://github.com/rails/rails/commit/10565895805887d4faf004a6f71219da177f78b7))
 
-* Introduced `bin/setup` script to bootstrap an application.
-  ([Pull Request](https://github.com/rails/rails/pull/15189))
+*   Introduced `bin/setup` script to bootstrap an application.
+    ([Pull Request](https://github.com/rails/rails/pull/15189))
 
-* Changed default value for `config.assets.digest` to `true` in development.
-  ([Pull Request](https://github.com/rails/rails/pull/15155))
+*   Changed default value for `config.assets.digest` to `true` in development.
+    ([Pull Request](https://github.com/rails/rails/pull/15155))
 
-* Introduced an API to register new extensions for `rake notes`.
-  ([Pull Request](https://github.com/rails/rails/pull/14379))
+*   Introduced an API to register new extensions for `rake notes`.
+    ([Pull Request](https://github.com/rails/rails/pull/14379))
+
+*   Introduced `Rails.gem_version` as a convenience method to return `Gem::Version.new(Rails.version)`.
+    ([Pull Request](https://github.com/rails/rails/pull/14101))
 
-* Introduced `Rails.gem_version` as a convenience method to return `Gem::Version.new(Rails.version)`.
-  ([Pull Request](https://github.com/rails/rails/pull/14101))
 
 Action Pack
 -----------
@@ -92,8 +93,8 @@ Please refer to the [Changelog][action-pack] for detailed changes.
 
 ### Deprecations
 
-* Deprecated support for setting the `:to` option of a router to a symbol or a
-  string that does not contain a `#` character:
+*   Deprecated support for setting the `:to` option of a router to a symbol or a
+    string that does not contain a `#` character:
 
     ```ruby
     get '/posts', to: MyRackApp    => (No change necessary)
@@ -106,17 +107,17 @@ Please refer to the [Changelog][action-pack] for detailed changes.
 
 ### Notable changes
 
-* `render nothing: true` or rendering a `nil` body no longer add a single space
-  padding to the response body.
-  ([Pull Request](https://github.com/rails/rails/pull/14883))
+*   `render nothing: true` or rendering a `nil` body no longer add a single
+    space padding to the response body.
+    ([Pull Request](https://github.com/rails/rails/pull/14883))
 
-* Introduced the `always_permitted_parameters` option to configure which
-  parameters are permitted globally. The default value of this configuration is
-  `['controller', 'action']`.
-  ([Pull Request](https://github.com/rails/rails/pull/15933))
+*   Introduced the `always_permitted_parameters` option to configure which
+    parameters are permitted globally. The default value of this configuration
+    is `['controller', 'action']`.
+    ([Pull Request](https://github.com/rails/rails/pull/15933))
 
-* The `*_filter` family methods has been removed from the documentation. Their
-  usage are discouraged in favor of the `*_action` family methods:
+*   The `*_filter` family methods has been removed from the documentation. Their
+    usage are discouraged in favor of the `*_action` family methods:
 
     ```
     after_filter          => after_action
@@ -141,22 +142,21 @@ Please refer to the [Changelog][action-pack] for detailed changes.
     (Commit [1](https://github.com/rails/rails/commit/6c5f43bab8206747a8591435b2aa0ff7051ad3de),
     [2](https://github.com/rails/rails/commit/489a8f2a44dc9cea09154ee1ee2557d1f037c7d4))
 
+*   Added HTTP method `MKCALENDAR` from RFC-4791
+    ([Pull Request](https://github.com/rails/rails/pull/15121))
 
-* Added HTTP method `MKCALENDAR` from RFC-4791
-  ([Pull Request](https://github.com/rails/rails/pull/15121))
-
-* `*_fragment.action_controller` notifications now include the controller and action name
-  in the payload.
-  ([Pull Request](https://github.com/rails/rails/pull/14137))
+*   `*_fragment.action_controller` notifications now include the controller and action name
+    in the payload.
+    ([Pull Request](https://github.com/rails/rails/pull/14137))
 
-* Segments that are passed into URL helpers are now automatically escaped.
-  ([Commit](https://github.com/rails/rails/commit/5460591f0226a9d248b7b4f89186bd5553e7768f))
+*   Segments that are passed into URL helpers are now automatically escaped.
+    ([Commit](https://github.com/rails/rails/commit/5460591f0226a9d248b7b4f89186bd5553e7768f))
 
-* Improved Routing Error page with fuzzy matching for route search.
-  ([Pull Request](https://github.com/rails/rails/pull/14619))
+*   Improved Routing Error page with fuzzy matching for route search.
+    ([Pull Request](https://github.com/rails/rails/pull/14619))
 
-* Added option to disable logging of CSRF failures.
-  ([Pull Request](https://github.com/rails/rails/pull/14280))
+*   Added option to disable logging of CSRF failures.
+    ([Pull Request](https://github.com/rails/rails/pull/14280))
 
 
 Action View
@@ -166,20 +166,20 @@ Please refer to the [Changelog][action-view] for detailed changes.
 
 ### Deprecations
 
-* Deprecated `AbstractController::Base.parent_prefixes`.
-  Override `AbstractController::Base.local_prefixes` when you want to change
-  where to find views.
-  ([Pull Request](https://github.com/rails/rails/pull/15026))
+*   Deprecated `AbstractController::Base.parent_prefixes`.
+    Override `AbstractController::Base.local_prefixes` when you want to change
+    where to find views.
+    ([Pull Request](https://github.com/rails/rails/pull/15026))
 
-* Deprecated `ActionView::Digestor#digest(name, format, finder, options = {})`,
-  arguments should be passed as a hash instead.
-  ([Pull Request](https://github.com/rails/rails/pull/14243))
+*   Deprecated `ActionView::Digestor#digest(name, format, finder, options = {})`,
+    arguments should be passed as a hash instead.
+    ([Pull Request](https://github.com/rails/rails/pull/14243))
 
 ### Notable changes
 
-* The form helpers no longer generate a `<div>` element with inline CSS around
-  the hidden fields.
-  ([Pull Request](https://github.com/rails/rails/pull/14738))
+*   The form helpers no longer generate a `<div>` element with inline CSS around
+    the hidden fields.
+    ([Pull Request](https://github.com/rails/rails/pull/14738))
 
 
 Action Mailer
@@ -189,9 +189,9 @@ Please refer to the [Changelog][action-mailer] for detailed changes.
 
 ### Notable changes
 
-* Added the `show_previews` configuration option for enabling mailer previews
-  outside of the development environment.
-  ([Pull Request](https://github.com/rails/rails/pull/15970))
+*   Added the `show_previews` configuration option for enabling mailer previews
+    outside of the development environment.
+    ([Pull Request](https://github.com/rails/rails/pull/15970))
 
 
 Active Record
@@ -203,111 +203,113 @@ for detailed changes.
 
 ### Removals
 
-* Removed `cache_attributes` and friends. All attributes are cached.
-  ([Pull Request](https://github.com/rails/rails/pull/15429))
+*   Removed `cache_attributes` and friends. All attributes are cached.
+    ([Pull Request](https://github.com/rails/rails/pull/15429))
 
-* Removed deprecated method `ActiveRecord::Base.quoted_locking_column`.
-  ([Pull Request](https://github.com/rails/rails/pull/15612))
+*   Removed deprecated method `ActiveRecord::Base.quoted_locking_column`.
+    ([Pull Request](https://github.com/rails/rails/pull/15612))
 
-* Removed deprecated `ActiveRecord::Migrator.proper_table_name`. Use the
-  `proper_table_name` instance method on `ActiveRecord::Migration` instead.
-  ([Pull Request](https://github.com/rails/rails/pull/15512))
+*   Removed deprecated `ActiveRecord::Migrator.proper_table_name`. Use the
+    `proper_table_name` instance method on `ActiveRecord::Migration` instead.
+    ([Pull Request](https://github.com/rails/rails/pull/15512))
 
-* Removed unused `:timestamp` type. Transparently alias it to `:datetime`
-  in all cases. Fixes inconsistencies when column types are sent outside of
-  `ActiveRecord`, such as for XML Serialization.
-  ([Pull Request](https://github.com/rails/rails/pull/15184))
+*   Removed unused `:timestamp` type. Transparently alias it to `:datetime`
+    in all cases. Fixes inconsistencies when column types are sent outside of
+    `ActiveRecord`, such as for XML Serialization.
+    ([Pull Request](https://github.com/rails/rails/pull/15184))
 
 ### Deprecations
 
-* Deprecated broken support for automatic detection of counter caches on
-  `has_many :through` associations. You should instead manually specify the
-  counter cache on the `has_many` and `belongs_to` associations for the through
-  records.
-  ([Pull Request](https://github.com/rails/rails/pull/15754))
+*   Deprecated broken support for automatic detection of counter caches on
+    `has_many :through` associations. You should instead manually specify the
+    counter cache on the `has_many` and `belongs_to` associations for the
+    through records.
+    ([Pull Request](https://github.com/rails/rails/pull/15754))
 
-* Deprecated `serialized_attributes` without replacement.
-  ([Pull Request](https://github.com/rails/rails/pull/15704))
+*   Deprecated `serialized_attributes` without replacement.
+    ([Pull Request](https://github.com/rails/rails/pull/15704))
 
-* Deprecated returning `nil` from `column_for_attribute` when no column exists.
-  It will return a null object in Rails 5.0
-  ([Pull Request](https://github.com/rails/rails/pull/15878))
+*   Deprecated returning `nil` from `column_for_attribute` when no column
+    exists. It will return a null object in Rails 5.0
+    ([Pull Request](https://github.com/rails/rails/pull/15878))
 
-* Deprecated using `.joins`, `.preload` and `.eager_load` with associations that
-  depends on the instance state (i.e. those defined with a scope that takes an
-  argument) without replacement.
-  ([Commit](https://github.com/rails/rails/commit/ed56e596a0467390011bc9d56d462539776adac1))
+*   Deprecated using `.joins`, `.preload` and `.eager_load` with associations
+    that depends on the instance state (i.e. those defined with a scope that
+    takes an argument) without replacement.
+    ([Commit](https://github.com/rails/rails/commit/ed56e596a0467390011bc9d56d462539776adac1))
 
-* Deprecated passing Active Record objects to `.find` or `.exists?`. Call `#id`
-  on the objects first.
-  (Commit [1](https://github.com/rails/rails/commit/d92ae6ccca3bcfd73546d612efaea011270bd270),
-  [2](https://github.com/rails/rails/commit/d35f0033c7dec2b8d8b52058fb8db495d49596f7))
+*   Deprecated passing Active Record objects to `.find` or `.exists?`. Call
+    `#id` on the objects first.
+    (Commit [1](https://github.com/rails/rails/commit/d92ae6ccca3bcfd73546d612efaea011270bd270),
+    [2](https://github.com/rails/rails/commit/d35f0033c7dec2b8d8b52058fb8db495d49596f7))
 
-* Deprecated half-baked support for PostgreSQL range values with excluding
-  beginnings. We currently map PostgreSQL ranges to Ruby ranges. This conversion
-  is not fully possible because the Ruby range does not support excluded
-  beginnings.
+*   Deprecated half-baked support for PostgreSQL range values with excluding
+    beginnings. We currently map PostgreSQL ranges to Ruby ranges. This conversion
+    is not fully possible because the Ruby range does not support excluded
+    beginnings.
 
-  The current solution of incrementing the beginning is not correct
-  and is now deprecated. For subtypes where we don't know how to increment
-  (e.g. `#succ` is not defined) it will raise an `ArgumentError` for ranges with
-  excluding beginnings.
+    The current solution of incrementing the beginning is not correct
+    and is now deprecated. For subtypes where we don't know how to increment
+    (e.g. `#succ` is not defined) it will raise an `ArgumentError` for ranges
+    with excluding beginnings.
 
-  ([Commit](https://github.com/rails/rails/commit/91949e48cf41af9f3e4ffba3e5eecf9b0a08bfc3))
+    ([Commit](https://github.com/rails/rails/commit/91949e48cf41af9f3e4ffba3e5eecf9b0a08bfc3))
 
 ### Notable changes
 
-* Added a `:required` option to singular associations, which defines a
-  presence validation on the association.
-  ([Pull Request](https://github.com/rails/rails/pull/16056))
+*   Added a `:required` option to singular associations, which defines a
+    presence validation on the association.
+    ([Pull Request](https://github.com/rails/rails/pull/16056))
 
-* Introduced `ActiveRecord::Base#validate!` that raises `RecordInvalid` if the
-  record is invalid.
-  ([Pull Request](https://github.com/rails/rails/pull/8639))
+*   Introduced `ActiveRecord::Base#validate!` that raises `RecordInvalid` if the
+    record is invalid.
+    ([Pull Request](https://github.com/rails/rails/pull/8639))
 
-* `ActiveRecord::Base#reload` now behaves the same as `m = Model.find(m.id)`,
-  meaning that it no longer retains the extra attributes from custom `select`s.
-  ([Pull Request](https://github.com/rails/rails/pull/15866))
+*   `ActiveRecord::Base#reload` now behaves the same as `m = Model.find(m.id)`,
+    meaning that it no longer retains the extra attributes from custom
+    `select`s.
+    ([Pull Request](https://github.com/rails/rails/pull/15866))
 
-* Introduced the `bin/rake db:purge` task to empty the database for the current
-  environment.
-  ([Commit](https://github.com/rails/rails/commit/e2f232aba15937a4b9d14bd91e0392c6d55be58d))
+*   Introduced the `bin/rake db:purge` task to empty the database for the
+    current environment.
+    ([Commit](https://github.com/rails/rails/commit/e2f232aba15937a4b9d14bd91e0392c6d55be58d))
 
-* `ActiveRecord::Dirty` now detects in-place changes to mutable values.
-  Serialized attributes on ActiveRecord models will no longer save when
-  unchanged. This also works with other types such as string columns and
-  json columns on PostgreSQL.
-  (Pull Requests [1](https://github.com/rails/rails/pull/15674),
-  [2](https://github.com/rails/rails/pull/15786),
-  [3](https://github.com/rails/rails/pull/15788))
+*   `ActiveRecord::Dirty` now detects in-place changes to mutable values.
+    Serialized attributes on ActiveRecord models will no longer save when
+    unchanged. This also works with other types such as string columns and json
+    columns on PostgreSQL.
+    (Pull Requests [1](https://github.com/rails/rails/pull/15674),
+    [2](https://github.com/rails/rails/pull/15786),
+    [3](https://github.com/rails/rails/pull/15788))
 
-* Added support for `#pretty_print` in `ActiveRecord::Base` objects.
-  ([Pull Request](https://github.com/rails/rails/pull/15172))
+*   Added support for `#pretty_print` in `ActiveRecord::Base` objects.
+    ([Pull Request](https://github.com/rails/rails/pull/15172))
 
-* PostgreSQL and SQLite adapters no longer add a default limit of 255 characters
-  on string columns.
-  ([Pull Request](https://github.com/rails/rails/pull/14579))
+*   PostgreSQL and SQLite adapters no longer add a default limit of 255
+    characters on string columns.
+    ([Pull Request](https://github.com/rails/rails/pull/14579))
 
-* `sqlite3:///some/path` now resolves to the absolute system path `/some/path`.
-  For relative paths, use `sqlite3:some/path` instead. (Previously, `sqlite3:///some/path`
-  resolved to the relative path `some/path`. This behaviour was deprecated on
-  Rails 4.1.)
-  ([Pull Request](https://github.com/rails/rails/pull/14569))
+*   `sqlite3:///some/path` now resolves to the absolute system path
+    `/some/path`. For relative paths, use `sqlite3:some/path` instead.
+    (Previously, `sqlite3:///some/path` resolved to the relative path
+    `some/path`. This behaviour was deprecated on Rails 4.1.)
+    ([Pull Request](https://github.com/rails/rails/pull/14569))
 
-* Introduced `#validate` as an alias for `#valid?`.
-  ([Pull Request](https://github.com/rails/rails/pull/14456))
+*   Introduced `#validate` as an alias for `#valid?`.
+    ([Pull Request](https://github.com/rails/rails/pull/14456))
 
-* `#touch` now accepts multiple attributes to be touched at once.
-  ([Pull Request](https://github.com/rails/rails/pull/14423))
+*   `#touch` now accepts multiple attributes to be touched at once.
+    ([Pull Request](https://github.com/rails/rails/pull/14423))
 
-* Added support for fractional seconds for MySQL 5.6 and above.
-  (Pull Request [1](https://github.com/rails/rails/pull/8240), [2](https://github.com/rails/rails/pull/14359))
+*   Added support for fractional seconds for MySQL 5.6 and above.
+    (Pull Request [1](https://github.com/rails/rails/pull/8240),
+    [2](https://github.com/rails/rails/pull/14359))
 
-* Added support for the `citext` column type in PostgreSQL adapter.
-  ([Pull Request](https://github.com/rails/rails/pull/12523))
+*   Added support for the `citext` column type in PostgreSQL adapter.
+    ([Pull Request](https://github.com/rails/rails/pull/12523))
 
-* Added support for user-created range types in PostgreSQL adapter.
-  ([Commit](https://github.com/rails/rails/commit/4cb47167e747e8f9dc12b0ddaf82bdb68c03e032))
+*   Added support for user-created range types in PostgreSQL adapter.
+    ([Commit](https://github.com/rails/rails/commit/4cb47167e747e8f9dc12b0ddaf82bdb68c03e032))
 
 
 Active Model
@@ -317,21 +319,21 @@ Please refer to the [Changelog][active-model] for detailed changes.
 
 ### Removals
 
-* Removed deprecated `Validator#setup` without replacement.
-  ([Pull Request](https://github.com/rails/rails/pull/15617))
+*   Removed deprecated `Validator#setup` without replacement.
+    ([Pull Request](https://github.com/rails/rails/pull/15617))
 
 ### Notable changes
 
-* Introduced `undo_changes` method in `ActiveModel::Dirty` to restore the
-  changed (dirty) attributes to their previous values.
-  ([Pull Request](https://github.com/rails/rails/pull/14861))
+*   Introduced `undo_changes` method in `ActiveModel::Dirty` to restore the
+    changed (dirty) attributes to their previous values.
+    ([Pull Request](https://github.com/rails/rails/pull/14861))
 
-* `has_secure_password` now verifies that the given password is less than 72
-  characters if validations are enabled.
-  ([Pull Request](https://github.com/rails/rails/pull/15708))
+*   `has_secure_password` now verifies that the given password is less than 72
+    characters if validations are enabled.
+    ([Pull Request](https://github.com/rails/rails/pull/15708))
 
-* Introduced `#validate` as an alias for `#valid?`.
-  ([Pull Request](https://github.com/rails/rails/pull/14456))
+*   Introduced `#validate` as an alias for `#valid?`.
+    ([Pull Request](https://github.com/rails/rails/pull/14456))
 
 
 Active Support
@@ -341,33 +343,37 @@ Please refer to the [Changelog][active-support] for detailed changes.
 
 ### Removals
 
-* Removed deprecated `Numeric#ago`, `Numeric#until`, `Numeric#since`,
-  `Numeric#from_now`. ([Commit](https://github.com/rails/rails/commit/f1eddea1e3f6faf93581c43651348f48b2b7d8bb))
+*   Removed deprecated `Numeric#ago`, `Numeric#until`, `Numeric#since`,
+    `Numeric#from_now`.
+    ([Commit](https://github.com/rails/rails/commit/f1eddea1e3f6faf93581c43651348f48b2b7d8bb))
 
-* Removed deprecated string based terminators for `ActiveSupport::Callbacks`.
-  ([Pull Request](https://github.com/rails/rails/pull/15100))
+*   Removed deprecated string based terminators for `ActiveSupport::Callbacks`.
+    ([Pull Request](https://github.com/rails/rails/pull/15100))
 
 ### Deprecations
 
-* Deprecated `Class#superclass_delegating_accessor`, use `Class#class_attribute`
-  instead. ([Pull Request](https://github.com/rails/rails/pull/14271))
+*   Deprecated `Class#superclass_delegating_accessor`, use
+    `Class#class_attribute` instead.
+    ([Pull Request](https://github.com/rails/rails/pull/14271))
 
-* Deprecated `ActiveSupport::SafeBuffer#prepend!` as `ActiveSupport::SafeBuffer#prepend`
-  now performs the same function. ([Pull Request](https://github.com/rails/rails/pull/14529))
+*   Deprecated `ActiveSupport::SafeBuffer#prepend!` as
+    `ActiveSupport::SafeBuffer#prepend` now performs the same function.
+    ([Pull Request](https://github.com/rails/rails/pull/14529))
 
 ### Notable changes
 
-* Added `Hash#transform_values` and `Hash#transform_values!` to simplify a
-  common pattern where the values of a hash must change, but the keys are left
-  the same.
-  ([Pull Request](https://github.com/rails/rails/pull/15819))
+*   Added `Hash#transform_values` and `Hash#transform_values!` to simplify a
+    common pattern where the values of a hash must change, but the keys are left
+    the same.
+    ([Pull Request](https://github.com/rails/rails/pull/15819))
 
-* The `humanize` inflector helper now strips any leading underscores.
-  ([Commit](https://github.com/rails/rails/commit/daaa21bc7d20f2e4ff451637423a25ff2d5e75c7))
+*   The `humanize` inflector helper now strips any leading underscores.
+    ([Commit](https://github.com/rails/rails/commit/daaa21bc7d20f2e4ff451637423a25ff2d5e75c7))
 
-* Introduce `Concern#class_methods` as an alternative to `module ClassMethods`,
-  as well as `Kernel#concern` to avoid the `module Foo; extend ActiveSupport::Concern; end`
-  boilerplate. ([Commit](https://github.com/rails/rails/commit/b16c36e688970df2f96f793a759365b248b582ad))
+*   Introduce `Concern#class_methods` as an alternative to
+    `module ClassMethods`, as well as `Kernel#concern` to avoid the
+    `module Foo; extend ActiveSupport::Concern; end` boilerplate.
+    ([Commit](https://github.com/rails/rails/commit/b16c36e688970df2f96f793a759365b248b582ad))
 
 
 Credits
@@ -375,8 +381,8 @@ Credits
 
 See the
 [full list of contributors to Rails](http://contributors.rubyonrails.org/) for
-the many people who spent many hours making Rails, the stable and robust
-framework it is. Kudos to all of them.
+the many people who spent many hours making Rails the stable and robust
+framework it is today. Kudos to all of them.
 
 [railties]:       https://github.com/rails/rails/blob/4-2-stable/railties/CHANGELOG.md
 [action-pack]:    https://github.com/rails/rails/blob/4-2-stable/actionpack/CHANGELOG.md