Additions based on /usr/lib/python2.7/distutils/archive_util.py
from the Ubuntu 12.04 package python2.7 (2.7.3-0ubuntu3.8). I have not
looked into the compatibility of the software licenses of Paramiko vs
distutils however the original setup_helper.py code in Paramiko was
clearly also copied from distutils so to be honest it's not like I'm
changing the status quo.