script for cloning a non-relocatable virtualenv

 Virtualenv provides a way to make virtualenv's relocatable which could then be
 copied as wanted. However making a virtualenv relocatable this way breaks
 the no-site-packages isolation of the virtualenv as well as other aspects that
 come with relative paths and '/usr/bin/env' shebangs that may be undesirable.
 .
 Also, the .pth and .egg-link rewriting doesn't seem to work as intended. This
 attempts to overcome these issues and provide a way to easily clone an
 existing virtualenv.