I tried to repeat the test in http://bugs.python.org/msg60749 and found
that the descriptors will close if you read from the file before closing.

so this leads to open descriptors::

  import urllib2
  f = urllib2.urlopen('http://www.google.com')
  f.close()

while this does not::

  import urllib2
  f = urllib2.urlopen('http://www.google.com')
  f.read(1)
  f.close()