Manually adding a doctype is ignored

[ser]

  def test_ticket_x_default
    doc = REXML::Document.new
    doc << REXML::XMLDecl.default
    doc << REXML::Element.new("a")

    str = ""
    doc.write(str)

    assert_equal("<?xml version='1.0'?><a/>", str)
  end

  def test_ticket_x_new
    doc = REXML::Document.new
    doc << REXML::XMLDecl.new("1.0", "UTF-8")
    doc << REXML::Element.new("a")

    str = ""
    doc.write(str)

    assert_equal("<?xml version='1.0' encoding='UTF-8'?><a/>", str)
  end