Issue with Rails 4.1 has_many uniq through and order

app.rb

require 'rubygems'
require 'active_record'
require 'logger'

ActiveRecord::Base.establish_connection(adapter: 'postgresql', host: 'localhost', database: 'test_database')
ActiveRecord::Base.logger = Logger.new(STDOUT)
logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table "authors", force: true do |t|
    t.string   "name"
    t.timestamps
  end

  create_table "authorships", id: false, force: true do |t|
    t.integer "author_id", null: false
    t.integer "zine_id", null: false
  end

  add_index "authorships", ["author_id", "zine_id"], name: "index_authorships_on_author_id_and_zine_id", unique: true, using: :btree

  create_table "zines", force: true do |t|
    t.string   "title", null: false
    t.boolean  "published", default: true
    t.timestamps
  end
end

class Author < ActiveRecord::Base
  has_many :authorships
  has_many :zines, through: :authorships

  scope :published, -> {
    joins(:zines)
      .merge(Zine.published)
      .except(:order)
      .distinct(Author.arel_table[:id])
      .order(name: :desc)
  }
end

class Zine < ActiveRecord::Base
  has_many :authorships
  has_many(:authors,
           -> { distinct },
           through: :authorships)

  scope :published, -> {
    where(published: true)
    .order(updated_at: :desc)
  }
end

class Authorship < ActiveRecord::Base
  belongs_to :author,
             validate: true,
             dependent: :destroy

  belongs_to :zine, validate: true
end

zine = Zine.create!(title: "A Guide to Becoming a Superhero", published: true)
author_1 = Author.create!(name: 'Alfred')
Authorship.create(zine_id: zine.id, author_id: author_1.id)

author_2 = Author.create!(name: 'Batman')
Authorship.create(zine_id: zine.id, author_id: author_2.id)

Author.create!(name: 'Robin') # Unpublished author
logger.debug Author.published

Gemfile

source 'https://rubygems.org'

# gem 'activerecord', '4.0.5'
gem 'activerecord', '4.1.1'
gem 'pg'

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    activemodel (4.1.1)
      activesupport (= 4.1.1)
      builder (~> 3.1)
    activerecord (4.1.1)
      activemodel (= 4.1.1)
      activesupport (= 4.1.1)
      arel (~> 5.0.0)
    activesupport (4.1.1)
      i18n (~> 0.6, >= 0.6.9)
      json (~> 1.7, >= 1.7.7)
      minitest (~> 5.1)
      thread_safe (~> 0.1)
      tzinfo (~> 1.1)
    arel (5.0.1.20140414130214)
    builder (3.2.2)
    i18n (0.6.9)
    json (1.8.1)
    minitest (5.3.3)
    pg (0.17.1)
    thread_safe (0.3.3)
    tzinfo (1.1.0)
      thread_safe (~> 0.1)

PLATFORMS
  ruby

DEPENDENCIES
  activerecord (= 4.1.1)
  pg