title: Error in Popen when using subprocess.py in windows
body: <pre><code>Traceback (most recent call last):
   File "script/oic_flow_tests.py", line 232, in &lt;module&gt;
     p1 =Popen(["./%s.py" % args.server], stdout=PIPE)
   File "C:\python27\lib\subprocess.py", line 709, in __init__
     errread, errwrite)
   File "C:\python27\lib\subprocess.py", line 957, in _execute_child
     startupinfo)
  WindowsError: [Error 2] Le fichier spÚcifiÚ est introuvable
  </code></pre>
  
  <p>(The French error means "file not found")</p>
  
  <p>I've tried to fix it by adding <code>shell=True</code> in <code>Popen</code>, but then another error appears:</p>
  
  <pre><code>ValueError: No JSON object could be decoded"
  </code></pre>