Can't install virtualenvwrapper on OSX 10.11 El Capitan
You can manually install the dependencies that don't exist on a stock 10.11 install, then install the other packages with --no-deps to ignore the dependencies. That way it will skip six (and argparse which is also already installed). This works on my 10.11 beta 6 install:
sudo pip install pbrsudo pip install --no-deps stevedoresudo pip install --no-deps virtualenvwrapperAnd no need to disable rootless.
sudo pip install virtualenvwrapper --ignore-installed sixAlso works