Ensure buildpack writes version in all cases
Ensure buildpack writes version in all cases

[#139017911]

Signed-off-by: Anna Thornton <0e9b4a17e1cf85a71a11118ecdbc866e5f8ffc65@pivotal.io>

cloudfoundry/python-buildpack,cloudfoundry/python-buildpack,cloudfoundry/python-buildpack