Move instantiation responsibilities from Inheritance to Persistence. Have Inheritance#discriminate_class_for_record handle STI lookup duties.

Added examples to current_page? method [ci skip]

augmented the Rails 4 guides with links back to Github

Allows you to do BaseClass.new(:type => "SubClass") as well as
parent.children.build(:type => "SubClass") or parent.build_child
to initialize an STI subclass. Ensures that the class name is a
valid class and that it is in the ancestors of the super class
that the association is expecting.

Add #seconds_until_end_of_day to DateTime and Time

[ci skip]

Fix typo in the Observers deprecation message.

Rather than just raising a NoMethodError when copying the config, this
commit adds a warning message until either the rails-observers gem is
installed or the relevant config options are removed.

They was extracted from a plugin.

See https://github.com/rails/rails-observers

[Rafael Mendonça França + Steve Klabnik]

Simplify String#mb_chars and fix documentation.

This behavior mattered under Ruby 1.8, but that doesn't matter now
that we don't support it.

In addition, we don't want to proxy the #class method. A test was added
to prevent against regressions.

This documentation has been out of date.

Ensure that associations have a symbol argument.

Fixes #7418.

Specify type of singular assication during serialization

When serialising a class, specify the type of any singular associations, if
necessary. Rails already correctly specifies the :type of any enumerable
association (e.g. a has_many association), but made no attempt to do so for
non-enumerables (e.g. a has_one association).
We must specify the :type of any STI association. A has_one
association to a class which uses single-table inheritance is an example of
this type of association.

Fixes #7471

Revert "rails gem has no lib directory to require"

This reverts commit 6bcbd604.

The default value for require_paths is ['lib'], and Rails does not
need to include any lib/ file to build the gem, so the previous
commit 'makes sense'. However, gems will not be built at all if
require_paths is empty (see https://gist.github.com/1065473), so
it's better to stick with the default, which does not have any
side-effects

This table is being used to verify if the :limit options is being
ignored for text and binary columns

Remove FIXME tag from abstract adapter test.

Use File.join to better integrate fixture_path in fixture_file_upload.

Cache digest opt out cleanup

Instead of deleting the skip_digest option flag, this changes the method to merely check the
key. This change is because of a discussion in this thread:

https://github.com/rails/rails/pull/8317

This commit also makes #fragment_name_with_digest private due to its
functionality being subsumed by #cache_fragment_name.

This reverts commit 33b29e01, reversing
changes made to ac8c7293.

Reason:

https://github.com/rails/rails/pull/4684#commitcomment-920313

default source in Gemfiles to :rubygems rather than hardcoding the URL

No sort Hash options in #grouped_options_for_select

* I guess this would be the preferrable default for Bundler
* current version of Bundler converts :rubygems into 'http://rubygems.org', not https://,
  and that will help those who are working on a very poor network environment that doesn't allow SSL