Non-blocking subprocess call

[Kevin Walzer]

I'm currently using os.popen in an application of mine, which calls for 
non-blocking data, in this fashion:

  self.file = os.popen('echo %s | sudo -S /sw/bin/fink -y install %s' % 
(self.passtext, self.packagename), 'r', os.O_NONBLOCK)

What is the equivalent/comparable call in the new subprocess module? I 
can't find any reference in the Python docs to non-blocking streams.

-- 
Kevin Walzer
Code by Kevin
http://www.codebykevin.com