python: force pyenv rehash after installing dependencies with pipenv
python: force pyenv rehash after installing dependencies with pipenv

While testing sometimes pyenv would not create shims for dependencies
with bins. This is hard to reproduce but forcing a pyenv rehash seems to
work as it'll create all missing shims.

lucasts/platforms,tsuru/platforms,tsuru/platforms,lucasts/platforms,tsuru/platforms,tsuru/platforms,lucasts/platforms