Code review comment for lp:~ev/adt-cloud-worker/support-virtualenv

We certainly can add venv support, since it's simple, but bear in mind that we are still only depending on deb packages (python3-kombu was backported to trusty) and I think much easier and better security-wise to avoid deploying pip.

Maybe there is room for developing with pip, but the versions already diverge and I am resistant to cover it in documentation instead of simply `apt-get install [deps]`.

Not a blocker to this MP, though.