Self executable gist to show the error of issue https://github.com/rails/rails/issues/13923 on Rails

active_record_master.rb

unless File.exist?('Gemfile')
  File.write('Gemfile', <<-GEMFILE)
    source 'https://rubygems.org'
    gem 'rails', github: 'rails/rails'
    gem 'arel', github: 'rails/arel'
    gem 'sqlite3'
  GEMFILE

  system 'bundle'
end

require 'bundler'
Bundler.setup(:default)

require 'active_record'
require 'minitest/autorun'
require 'logger'

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :people do |t|
    t.string :name
  end

  create_table :relatives do |t|
    t.boolean :adopted
  end

  create_table :people_relatives do |t|
    t.integer :person_id
    t.integer :relative_id
  end
end

class Person < ActiveRecord::Base
  has_and_belongs_to_many :relatives, :autosave => true
end

class Relative < ActiveRecord::Base
end

class PeopleRelative < ActiveRecord::Base
end

class BugTest < Minitest::Test
  def test_association_stuff
    person = Person.create!
    relative = Relative.create!
    person.relatives << relative
    person.name = 'John Doe'
    relative.adopted = false
    person.save!
    person.reload
    relative.reload

    assert_equal 'John Doe', person.name
    assert_equal false, relative.adopted
  end
end