Do not try to write timestamps if they are missing #8813
[ci skip] Mention the change in nil handling for serialized attributes
in "Upgrading from Rails 3.2 to Rails 4.0"
[ci skip] Clarify the "Serialized Attributes" section

Mention that the change in nil handling for serialized attributes
affects custom coders.
Avoid relying on error messages when rescuing

When we are rescuing from an error, it's a brittle approach to do checks
with regular expressions on the raised message because it may change in
in the future and error messages are different across implementations.

The NameError API could be improved at the MRI level but for now we need
to rely on its #name. A #== check will only pass for top level constants
or only when the last constant of the path is missing so we need to rely
on #include? instead. For instance:

    begin
      Namespace::Foo
    rescue NameError => e
      e.name # => :Namespace
    end

However, if the name-space already exists, only the name of the first
missing constant in the path is returned (e.g. for Math::PHI, the name
would be :PHI). JRuby will return a fully qualified name (:"Math::PHI").

We need to keep the == check for 1.9 compatibility since const_get will
raise a NameError with a name attribute set to the given string if it's
one of "::" or "".

See http://git.io/jnSN7g for further information.
Merge pull request #16300 from vast/mention-changes-to-nil-serialization-in-upgrading-from-3.2

Mention changes to `nil` handling in serialized attributes
Fixed issue w/custom accessors + reserved name + inheritance

Fixed an issue where custom accessor methods (such as those generated by
`enum`) with the same name as a global method are incorrectly overridden
when subclassing.

This was partially fixed in 4155431 then broken again by e5f15a8.

Fixes #16288.
update error message to reflect that the record could have been destroyed
Merge pull request #16456 from lsylvester/improve-active-record-error-message-on-update_columns-for-destroyed-records

Change error message in update_columns for destroyed objects
[ci skip] Fix broken url in plugins guide
Merge pull request #16472 from y-yagi/patch-1

[ci skip] Fix broken url in plugins guide
users_dont_suck_but_only_we_suck_and_only_our_tests_are_order_dependent!

Calling ActiveSupport::TestCase.i_suck_and_my_tests_are_order_dependent! in AS::TestCase makes
everyone's tests order dependent, which should never be done by the framework.
Remove old setup from AS test case

This was added back in Rails 3 on
c4a6109286909c394e8c5bfc471a1eb9de245d2b, and is not being used anymore.
CHANGELOG entry for TestCase.i_suck_and_my_tests_are_order_dependent! fix
use 'based on' instead of 'based off' [ci skip]
Nobody sucks so nobody should call this awful method name
Merge pull request #16476 from akshay-vishnoi/doc-changes

[ci skip] use "based on" or "based off of"
:bomb:
Add config option for cookies digest

You can now configure custom digest for cookies in the same way as `serializer`:

  config.action_dispatch.cookies_digest = 'SHA256'
add I18n support for `:placeholder` HTML option is passed to form fields
[ci skip] Updated where scope to conform to new style