Revert "Merge branch 'master' of github.com:rails/docrails"

This reverts commit 70d6e16fbad75b89dd1798ed697e7732b8606fa3, reversing
changes made to ea4db3bc078fb3093ecdddffdf4f2f4ff3e1e8f9.

Seems to be a code merge done by mistake.

8 files changed, 62 insertions, 52 deletions

diff --git a/guides/source/_welcome.html.erb b/guides/source/_welcome.html.erb
index 0a0a958e30..9210c40c17 100644
--- a/guides/source/_welcome.html.erb
+++ b/guides/source/_welcome.html.erb
@@ -15,7 +15,7 @@
 </p>
 <% end %>
 <p>
-  The guides for Rails 3.2.x are available at <a href="http://guides.rubyonrails.org/v3.2.14/">http://guides.rubyonrails.org/v3.2.14/</a>.
+  The guides for Rails 3.2.x are available at <a href="http://guides.rubyonrails.org/v3.2.13/">http://guides.rubyonrails.org/v3.2.13/</a>.
 </p>
 <p>
   The guides for Rails 2.3.x are available at <a href="http://guides.rubyonrails.org/v2.3.11/">http://guides.rubyonrails.org/v2.3.11/</a>.
diff --git a/guides/source/action_mailer_basics.md b/guides/source/action_mailer_basics.md
index d5a8ce4bf9..bf34799eb3 100644
--- a/guides/source/action_mailer_basics.md
+++ b/guides/source/action_mailer_basics.md
@@ -105,7 +105,7 @@ will be the template used for the email, formatted in HTML:
     <h1>Welcome to example.com, <%= @user.name %></h1>
     <p>
       You have successfully signed up to example.com,
-      your username is: <%= @user.login %>.<br>
+      your username is: <%= @user.login %>.<br/>
     </p>
     <p>
       To login to the site, just follow this link: <%= @url %>.
diff --git a/guides/source/action_view_overview.md b/guides/source/action_view_overview.md
index f4218994ae..3542844f33 100644
--- a/guides/source/action_view_overview.md
+++ b/guides/source/action_view_overview.md
@@ -68,7 +68,7 @@ Consider the following loop for names:
 ```html+erb
 <h1>Names of all the people</h1>
 <% @people.each do |person| %>
-  Name: <%= person.name %><br>
+  Name: <%= person.name %><br/>
 <% end %>
 ```
 
diff --git a/guides/source/active_record_querying.md b/guides/source/active_record_querying.md
index 9252a248b2..0592821a14 100644
--- a/guides/source/active_record_querying.md
+++ b/guides/source/active_record_querying.md
@@ -514,13 +514,7 @@ SELECT * FROM clients WHERE (clients.orders_count IN (1,3,5))
 Post.where.not(author: author)
 ```
 
-In other words, this query can be generated by calling `where` with no argument,
-then immediately chain with `not` passing `where` conditions. This will generate
-SQL code like this:
-
-```sql
-SELECT * FROM posts WHERE (author_id != 1)
-```
+In other words, this query can be generated by calling `where` with no argument, then immediately chain with `not` passing `where` conditions.
 
 Ordering
 --------
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md
index be5e47584e..ca023f7f66 100644
--- a/guides/source/active_support_core_extensions.md
+++ b/guides/source/active_support_core_extensions.md
@@ -96,13 +96,12 @@ INFO: The predicate for strings uses the Unicode-aware character class `[:space:
 
 WARNING: Note that numbers are not mentioned. In particular, 0 and 0.0 are **not** blank.
 
-For example, this method from `ActionController::HttpAuthentication::Token::ControllerMethods` uses `blank?` for checking whether a token is present:
+For example, this method from `ActionDispatch::Session::AbstractStore` uses `blank?` for checking whether a session key is present:
 
 ```ruby
-def authenticate(controller, &login_procedure)
-  token, options = token_and_options(controller.request)
-  unless token.blank?
-    login_procedure.call(token, options)
+def ensure_session_key!
+  if @key.blank?
+    raise ArgumentError, 'A key is required...'
   end
 end
 ```
@@ -421,9 +420,9 @@ NOTE: Defined in `active_support/core_ext/object/with_options.rb`.
 
 ### JSON support
 
-Active Support provides a better implemention of `to_json` than the `json` gem ordinarily provides for Ruby objects. This is because some classes, like `Hash` and `OrderedHash` needs special handling in order to provide a proper JSON representation.
+Active Support provides a better implemention of `to_json` than the +json+ gem ordinarily provides for Ruby objects. This is because some classes, like +Hash+ and +OrderedHash+ needs special handling in order to provide a proper JSON representation.
 
-Active Support also provides an implementation of `as_json` for the `Process::Status` class.
+Active Support also provides an implementation of `as_json` for the <tt>Process::Status</tt> class.
 
 NOTE: Defined in `active_support/core_ext/object/to_json.rb`.
 
@@ -2000,7 +1999,7 @@ Produce a string representation of a number in human-readable words:
 1234567890123456.to_s(:human)  # => "1.23 Quadrillion"
 ```
 
-NOTE: Defined in `active_support/core_ext/numeric/conversions.rb`.
+NOTE: Defined in `active_support/core_ext/numeric/formatting.rb`.
 
 Extensions to `Integer`
 -----------------------
@@ -2058,7 +2057,7 @@ BigDecimal.new(5.00, 6).to_s  # => "5.0"
 
 ### `to_formatted_s`
 
-The method `to_formatted_s` provides a default specifier of "F".  This means that a simple call to `to_formatted_s` or `to_s` will result in floating point representation instead of engineering notation:
+Te method `to_formatted_s` provides a default specifier of "F".  This means that a simple call to `to_formatted_s` or `to_s` will result in floating point representation instead of engineering notation:
 
 ```ruby
 BigDecimal.new(5.00, 6).to_formatted_s  # => "5.0"
@@ -2445,7 +2444,7 @@ dup[1][2] = 4
 array[1][2] == nil   # => true
 ```
 
-NOTE: Defined in `active_support/core_ext/object/deep_dup.rb`.
+NOTE: Defined in `active_support/core_ext/array/deep_dup.rb`.
 
 ### Grouping
 
@@ -2671,7 +2670,45 @@ hash[:b][:e] == nil      # => true
 hash[:b][:d] == [3, 4]   # => true
 ```
 
-NOTE: Defined in `active_support/core_ext/object/deep_dup.rb`.
+NOTE: Defined in `active_support/core_ext/hash/deep_dup.rb`.
+
+### Diffing
+
+The method `diff` returns a hash that represents a diff of the receiver and the argument with the following logic:
+
+* Pairs `key`, `value` that exist in both hashes do not belong to the diff hash.
+
+* If both hashes have `key`, but with different values, the pair in the receiver wins.
+
+* The rest is just merged.
+
+```ruby
+{a: 1}.diff(a: 1)
+# => {}, first rule
+
+{a: 1}.diff(a: 2)
+# => {:a=>1}, second rule
+
+{a: 1}.diff(b: 2)
+# => {:a=>1, :b=>2}, third rule
+
+{a: 1, b: 2, c: 3}.diff(b: 1, c: 3, d: 4)
+# => {:a=>1, :b=>2, :d=>4}, all rules
+
+{}.diff({})        # => {}
+{a: 1}.diff({})    # => {:a=>1}
+{}.diff(a: 1)      # => {:a=>1}
+```
+
+An important property of this diff hash is that you can retrieve the original hash by applying `diff` twice:
+
+```ruby
+hash.diff(hash2).diff(hash2) == hash
+```
+
+Diffing hashes may be useful for error messages related to expected option hashes for example.
+
+NOTE: Defined in `active_support/core_ext/hash/diff.rb`.
 
 ### Working with Keys
 
@@ -3806,13 +3843,13 @@ def default_helper_module!
   module_path = module_name.underscore
   helper module_path
 rescue MissingSourceFile => e
-  raise e unless e.is_missing? "helpers/#{module_path}_helper"
+  raise e unless e.is_missing? "#{module_path}_helper"
 rescue NameError => e
   raise e unless e.missing_name? "#{module_name}Helper"
 end
 ```
 
-NOTE: Defined in `actionpack/lib/abstract_controller/helpers.rb`.
+NOTE: Defined in `active_support/core_ext/name_error.rb`.
 
 Extensions to `LoadError`
 -------------------------
@@ -3835,4 +3872,4 @@ rescue NameError => e
 end
 ```
 
-NOTE: Defined in `actionpack/lib/abstract_controller/helpers.rb`.
+NOTE: Defined in `active_support/core_ext/load_error.rb`.
diff --git a/guides/source/command_line.md b/guides/source/command_line.md
index 18c4b1f366..5f98326c57 100644
--- a/guides/source/command_line.md
+++ b/guides/source/command_line.md
@@ -381,13 +381,12 @@ About your application's environment
 Ruby version              1.9.3 (x86_64-linux)
 RubyGems version          1.3.6
 Rack version              1.3
-Rails version             4.1.0
+Rails version             4.0.0
 JavaScript Runtime        Node.js (V8)
-Active Record version     4.1.0
-Action Pack version       4.1.0
-Action View version       4.1.0
-Action Mailer version     4.1.0
-Active Support version    4.1.0
+Active Record version     4.0.0
+Action Pack version       4.0.0
+Action Mailer version     4.0.0
+Active Support version    4.0.0
 Middleware                Rack::Sendfile, ActionDispatch::Static, Rack::Lock, #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x007ffd131a7c88>, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::DebugExceptions, ActionDispatch::RemoteIp, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::Migration::CheckPending, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::EncryptedCookieStore, ActionDispatch::Flash, ActionDispatch::ParamsParser, Rack::Head, Rack::ConditionalGet, Rack::ETag
 Application root          /home/foobar/commandsapp
 Environment               development
diff --git a/guides/source/development_dependencies_install.md b/guides/source/development_dependencies_install.md
index 415cedc4d6..5647a4c1b7 100644
--- a/guides/source/development_dependencies_install.md
+++ b/guides/source/development_dependencies_install.md
@@ -57,15 +57,9 @@ If you are on Fedora or CentOS, you can run
 $ sudo yum install libxml2 libxml2-devel libxslt libxslt-devel
 ```
 
-If you are running Arch Linux, you're done with:
-
-```bash
-$ sudo pacman -S libxml2 libxslt
-```
-
 If you have any problems with these libraries, you can install them manually by compiling the source code. Just follow the instructions at the [Red Hat/CentOS section of the Nokogiri tutorials](http://nokogiri.org/tutorials/installing_nokogiri.html#red_hat__centos) .
 
-Also, SQLite3 and its development files for the `sqlite3` gem — in Ubuntu you're done with just
+Also, SQLite3 and its development files for the `sqlite3-ruby` gem — in Ubuntu you're done with just
 
 ```bash
 $ sudo apt-get install sqlite3 libsqlite3-dev
@@ -77,12 +71,6 @@ And if you are on Fedora or CentOS, you're done with
 $ sudo yum install sqlite3 sqlite3-devel
 ```
 
-If you are on Arch Linux, you will need to run:
-
-```bash
-$ sudo pacman -S sqlite
-```
-
 Get a recent version of [Bundler](http://gembundler.com/)
 
 ```bash
@@ -149,14 +137,6 @@ $ sudo yum install mysql-server mysql-devel
 $ sudo yum install postgresql-server postgresql-devel
 ```
 
-If you are running Arch Linux, MySQL isn't supported anymore so you will need to
-use MariaDB instead (see [this announcement](https://www.archlinux.org/news/mariadb-replaces-mysql-in-repositories/)):
-
-```bash
-$ sudo pacman -S mariadb libmariadbclient mariadb-clients
-$ sudo pacman -S postgresql postgresql-libs
-```
-
 After that, run:
 
 ```bash
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 656e6d9956..b7ec747a77 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -322,7 +322,7 @@ config.assets.js_compressor = :uglifier
 
 ### sass-rails
 
-* `asset-url` with two arguments is deprecated. For example: `asset-url("rails.png", image)` becomes `asset-url("rails.png")`
+* `asset_url` with two arguments is deprecated. For example: `asset-url("rails.png", image)` becomes `asset-url("rails.png")`
 
 Upgrading from Rails 3.1 to Rails 3.2
 -------------------------------------