title: python 2.7 and 3.3 subprocess module difference
body: <p>I have the following code</p>
  
  <pre><code>from __future__ import print_function
  import subprocess
  
  p = subprocess.Popen(['cat'], stdin=subprocess.PIPE, stdout=subprocess.PIPE)
  p.kill()
  p.wait()
  print(p.stdin.write(b'some'))
  </code></pre>
  
  <p>and I ran it with python 2.7 and python 3.3. With python 2.7 an exception is thrown when I try to write to stdin. With python 3.3 this code prints 4. What is the difference between python 2.7 subprocess module and python 3.3?</p>