rather than exiting the process.

Extend date_select helper functionality.

Conflicts:
	actionpack/CHANGELOG.md

Setting the action_dispatch.rack_cache options to true or a hash should
be the way to enable it.

Credit for previous commit [ci skip]

active_model/validations requires necessary files to run

attributes

Only compile non-js/css under app/assets by default

Switch to new sprockets-rails plugin

Also remove references for RAILS_ASSET_ID from the guides

[ci skip]

Removed the asset_path configuration from the guides and added an entry
in the upgrading_ruby_on_rails guide

[ci skip]

Add a lock on the cache so that we don't have concurrency issues when
calculating the cache.

Fix bug with presence validation of associations.

Would incorrectly add duplicated errors when the association was blank. Bug introduced in 1fab518c.

Dup'ed ActiveRecord objects may not share the errors object 

Call super to nullify the reference to the original errors object in the dup'ed object (call ActiveModel::Validations#initialize_dup). Closes #7291

Add :platform to redcarpet gem, pointing to :ruby only.

This file is used at least by Active Merchant, its existence
is maybe not necessary but no big deal either.

This reverts commit ae9b3d7c.