machine:
    pre:
        - sudo rm /home/ubuntu/virtualenvs/venv-system/lib/python2.7/no-global-site-packages.txt

dependencies:
    pre:
        - sudo rm /home/ubuntu/virtualenvs/venv-system/lib/python2.7/no-global-site-packages.txt

Delete virtualenv configuration for no site packages
Delete virtualenv configuration for no site packages
