Datamapper DataMapper → 1.0.0

The following code:

require 'rubygems'
require 'dm-core'

include DataMapper::Types

class Root
  include DataMapper::Resource

  property :id, Serial
  property :name, String
  property :type, Discriminator
end

class Branch < Root
  property :value, Integer
end

DataMapper.setup(:default, {:adapter => 'sqlite3', :database => 'test.db'})
DataMapper.auto_migrate!

branch_one = Branch.new
branch_one.name = "branch one"
branch_one.value = 42

branch_one.save

entities = Root.all

p entities[0].value

raises an ArgumentError, coming from an assert in Query. The cause is that entities[0] is recognized as a Root while it is a Branch instead in the Query constructor (line 590 in query.rb), which determines @property to be Root.properties and not Branch.properties and then causes the assert fail in assert_valid_fields