utf-8 broken in jruby 1.7.2 windows

gistfile1.rb

# encoding: utf-8 

require 'tempfile'

def valid_utf8(str)
  str.encoding == Encoding::UTF_8 && str.valid_encoding?	
end

str = <<-EOF
My UTF-8 String: ✓ ®
EOF

puts str

puts "Original valid utf-8? #{valid_utf8(str)}"

file = Tempfile.new('temp')
path = file.path

file.write(str)
file.rewind

read = file.read
puts "Read #1 valid? #{valid_utf8(read)}"
file.close

read = File.read(path)
puts "Read #2 valid? #{valid_utf8(read)}"

read = File.read(path, :encoding => 'utf-8')
puts "Read #3 valid? #{valid_utf8(read)}"

read = File.open(path, 'r:utf-8') {|f| f.read}
puts "Read #4 valid? #{valid_utf8(read)}"

File.unlink path

File.open(path, 'w:utf-8'){|f| f.write str }

read = File.read(path)
puts "Read #5 valid? #{valid_utf8(read)}"

read = File.read(path, :encoding => 'utf-8')
puts "Read #6 valid? #{valid_utf8(read)}"

read = File.open(path, 'r:utf-8'){|f| f.read }
puts "Read #7 valid? #{valid_utf8(read)}"