irb(main):008:0> a = File.new 'a', 'w'
=> #<File:a>
irb(main):009:0> a.write_nonblock 'abc'
Errno::EBADF: Bad file descriptor - a
        from (irb):9:in `write_nonblock'
        from (irb):9
        from :0

Is this a bug? [mingw32]
Thanks for your help.
-=R