initial_state_bug.rb

unless File.exist?('Gemfile')
  File.write('Gemfile', <<-GEMFILE)
    source 'https://rubygems.org'
    gem 'activerecord', '4.2.1'
    gem 'state_machines'
    gem 'sqlite3'
    gem 'minitest'
  GEMFILE

  system 'bundle'
end

require 'bundler'
Bundler.setup(:default)

# Activate the gem you are reporting the issue against.
require 'active_record'
require 'minitest/autorun'
require 'logger'
require 'state_machines'

# Ensure backward compatibility with Minitest 4
Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)

# 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 :lights, force: true do |t|
    t.string :state
  end
end

class Light < ActiveRecord::Base
  state_machine initial: :green do
    state :green
    state :yellow
    state :red
  end
end

class BugTest < Minitest::Test
  def test_initial_state
    light = Light.new
    assert_equal 'green', light.state

    light.save!
    light = Light.find(light.id)

    refute_equal nil, light.state
    assert_equal 'green', light.state
  end
end

Corrected version in my fork: https://gist.github.com/RaVbaker/5d076449247e5e0fc453