Add rake test description

No behavior change
Typppo
Fix ActiveRecord `subclass_from_attrs` when eager_load is false.
It cannot find subclass because all classes are loaded automatically
when it needs.
Update capture_helper.rb

if there's content for the right column, then we need the two-column class, if not the one-column
Use the instrumentation framework to instrument Strong Params
fixes active_record_querying #pluck example
remove the new metadata note in Rails 4 upgrade guide

this was pulled out of Rails 4, see rails/rails#8399 for the discussion
Some copy edit and formatting for upgrading guide.
Explained how merging of scope works
fixing typo in the merging scopes section
Merge pull request #9497 from route/subclass_from_attrs

Fix ActiveRecord `subclass_from_attrs` when eager_load is false.

Conflicts:
	activerecord/CHANGELOG.md
Avoid short-circuit return
Make sure options is a hash
The console --sandbox transaction should not be joinable

Thanks @neerajdotname for noticing this bug.
Fix changelog indent, remove self from method call in changelog/doc examples

[ci skip]
Refactored nested associations so they are more readable. Added comments
which make it clearer about what's going on.
Merge pull request #9614 from wangjohn/refactoring_nested_associations_for_readability

Refactored nested associations so they are more readable.
Fix incorrectly appended square brackets to a multiple select box

If an explicit name has been given and it already ends with "[]"

Before:

    select(:category, [], {}, multiple: true, name: "post[category][]")
    # => <select name="post[category][][]" ...>

After:

    select(:category, [], {}, multiple: true, name: "post[category][]")
    # => <select name="post[category][]" ...>
Merge pull request #8670 from sanemat/fix/rake-desc

Add rake test description
Adding a note for :body option in `mail` method.