Rails bug

bug.rb

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

ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :seeds do |t|
    t.string :seed_type
  end

  create_table :plants do |t|
    t.string :seed_type
  end

  create_table :flowers do |t|
    t.integer :plant_id
    t.string :color
  end
end

class Seed < ActiveRecord::Base
  has_many :plants, -> seed { where :seed_type, seed.seed_type }
  has_many :flowers, through: :plants
end

class Plant < ActiveRecord::Base
  has_many :flowers
end

class Flower < ActiveRecord::Base
end

class BugTest < Minitest::Test
  def test_hmt_with_conditions
    poppy_seed = Seed.create!(seed_type: 'Poppy')
    poppy_plant = Plant.create!(seed_type: 'Poppy')
    poppy_plant.flowers.create!(color: 'red')
    poppy_seed.reload
    poppy_seed.flowers
  end
end