Merge pull request #10400 from frodsan/add_changelog_entry_for_a8ef0bbb

Add changelog entry for a8ef0bbb and update CHANGELOGs format

actionmailer/CHANGELOG.md

+## unreleased ##
+
+*   No changes.
+
+
 ## Rails 4.0.0.rc1 (April 29, 2013) ##
 
 * No changes.

actionpack/CHANGELOG.md

+## unreleased ##
+
+*   No changes.
+
+
 ## Rails 4.0.0.rc1 (April 29, 2013) ##
 
 *   Add support for passing custom url options other than `:host` and custom

activerecord/CHANGELOG.md

+## unreleased ##
+
 *   Mute `psql` output when running rake db:schema:load.
 
     *Godfrey Chan*
 
+
 ## Rails 4.0.0.rc1 (April 29, 2013) ##
 
 *   Trigger a save on `has_one association=(associate)` when the associate contents have changed.

activesupport/CHANGELOG.md

+## unreleased ##
+
+*  Remove multiple parameters support of `Object#in?`.
+
+   *Brian Morearty*
+
+
 ## Rails 4.0.0.rc1 (April 29, 2013) ##
 
 *   Fix skipping of filters defined by objects in `ActiveSupport::Callbacks::Callback`.

guides/CHANGELOG.md

+## unreleased ##
+
+*   No changes.
+
+
 ## Rails 4.0.0.rc1 (April 29, 2013) ##
 
 *   Change Service pages(404, etc). *Stanislav Sobolev*

railties/CHANGELOG.md

+## unreleased ##
+
+*  No changes.
+
+
 ## Rails 4.0.0.rc1 (April 29, 2013) ##
 
 *   Move rails.png into a data-uri. One less file to get generated into a new