Rails issue: missing require

missing_require.rb

begin
  require 'bundler/inline'
rescue LoadError => e
  $stderr.puts 'Bundler version 1.10 or later is required. Please update your Bundler'
  raise e
end

gemfile(true) do
  source 'https://rubygems.org'
  gem 'rails', github: 'rails/rails'
end

require 'active_support'
require 'active_support/hash_with_indifferent_access'
require 'minitest/autorun'

class BugTest < Minitest::Test
  def test_nested_hash
    hwia = HashWithIndifferentAccess.new
    hwia[:nested_hash] = {a: 1}
    # the line above raises 
    #   NoMethodError: undefined method `nested_under_indifferent_access' for {:a=>1}:Hash
    #   ../bundler/gems/rails-125ecfbbff33/activesupport/lib/active_support/hash_with_indifferent_access.rb:291:in `convert_value'
    #   ../bundler/gems/rails-125ecfbbff33/activesupport/lib/active_support/hash_with_indifferent_access.rb:104:in `[]='
  end
end