When updating to 2.3.4 I noticed that touch is
no longer a simple ‘update :updated_at’, but a save!,
which caused some code to break
(e.g. touch`ing in after_save == loop)

Usage

User.first.touch_without_callbacks
User.touch_without_callbacks([User.first.id, User.last.id])

Install
Paste somewhere…

# Provide .touch as it was in 2.3.2, simply update the :updated_at field.
class ActiveRecord::Base
  def touch_without_callbacks
    now = Time.now.utc
    self.class.touch_without_callbacks(id, now)
    self.updated_at = now
  end

  def self.touch_without_callbacks(ids, time=Time.now.utc)
    update_all({:updated_at=>time}, :id=>ids)
  end
end