Open3 : tcgetattr: Inappropriate ioctl for device

ruby-talk
1

I'm using Open3 to simulate a pseudo-terminal connection with ssh.
Everything seems to work well except i get the following warning/error
when connecting :

tcgetattr: Inappropriate ioctl for device

here is my ruby code :

···

------------------------------------------------------------------------
#! /usr/bin/env ruby

require 'open3'

ansi_red="\e[31m"
ansi_clear="\e[0m"

system "stty cbreak isig" # isig unusefull ?

# tcgetattr: Inappropriate ioctl for device
Open3.popen3("ssh -t -t TT") { |stdin, stdout, stderr|
  STDOUT.sync=true
  #stdin.puts "cd /mnt/fat/4tt;ls -Al"
  Thread.start do
    while c=STDIN.getc
      stdin.print c.chr
    end
  end
  Thread.start do
    while line=stderr.gets
      puts ansi_red+line.chomp+ansi_clear
    end
  end
  while c=stdout.getc
    print c.chr
  end
}

system "stty -cbreak -isig"
------------------------------------------------------------------------

what could be the right ioctl setup ?
I'm a complete newbie in using process, pipe, fork and tty...
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