title: Popen.poll() is returning 1
body: <p>I am using the python <a href="https://docs.python.org/2/library/subprocess.html" rel="nofollow noreferrer">subprocess</a> module to create subprocesses. I check the status of subprocess by using the Popen.poll() method. </p>
  
  <p>The documentation of subprocess module mention about negative value and none value return codes. But not about positive return codes.Popen.poll() is returning 1 in my case. What does that mean?</p>
  
  <blockquote>
    <p>The child return code, set by poll() and wait() (and indirectly by communicate()). A None value indicates that the process hasn’t terminated yet.
    A negative value -N indicates that the child was terminated by signal N (Unix only).</p>
  </blockquote>