virtualenv 20.0.24 creates ~/.local/share/virtualenv with the
seed packages needed for making virtualenvs per-python version.
Creating empty virtualenvs is quick, so run those in sequence
to avoid race possibilities. Then, we can still run the
installs into the virtualenvs in parallel.
We also fix a bug in the console stream functional jobs and install pip
with the use of ensure-pip. This is necessary because the virtualenv
fix runs the stream functional jobs and the update to the stream
functional jobs relies on working docker images.