mkvirtualenvのよく分かんエラー

mkvirtualenv --python=/usr/bin/python2.7 --no-site-package example

OSError: Command E:\Documents\proj\venv\Scripts\python.exe -c "import sys, pip;
pip...ll\"] + sys.argv[1:])" setuptools pip failed with error code 1

参考URL:http://stackoverflow.com/questions/20925329/trouble-with-creating-a-virtual-environment-in-windows-8-python-3-3

sudo easy_install virtualenv==1.10.1

これで解決した