Fix version parsing bug.
Fix version parsing bug.

psrthegreat/heroku-buildpack-python-sklearn,psrthegreat/heroku-buildpack-python-sklearn,psrthegreat/heroku-buildpack-python-sklearn,rajpurkar/heroku-buildpack-python-sklearn,rajpurkar/heroku-buildpack-python-sklearn,rajpurkar/heroku-buildpack-python-sklearn