The docker image that we build the zuul executor from is a Debian
image, but it does not follow the same python3 policies as Debian
itself. While we would not necessarily expect all roles to work
on the executor, it is reasonable to want to use the ensure-pip
role (which logically should be a no-op on the executor) for the
side effect of finding and returning the appropriate pip command.
Currently, the role fails on the executor because it mistakenly
concludes that it must install python3-venv to get a working
venv module. By increasing the precision of the check for what
is missing (the actual error is a missing "ensurepip" python module
(oh irony!), we can avoid attempting an installation of
python3-venv on python docker images (including the Zuul executor
images).
This also adds the ensure-pip-localhost job
This tests that the ensure-pip role works on the Zuul executor.
The executor is a debian host with a working python environment,
so it should be a no-op (and no packages should need to be installed).
Change-Id: Id7f13f2f73d45e680f79c00a83751b185212a63d
82d3910b17