The current ansible bootstrap process tried to
pin the versions of pip, setuptools and wheel
on the host and also uses inherited python
packages from the host. This causes problems
when the host has a version of setuptools which
is cannot be changed (perhaps due to some bug)
or when the host has otherwise undesirable
python packages.
The ansible bootstrap process only needs to
be concerned with whether pip is installed
and understands how to use constraints.
From there we can bootstrap the venv using
get-pip and completely avoid package conflicts
with the host. Once Ansible is bootstrapped,
the pip_install role will ensure that pip,
setuptools and wheel are correctly bootstrapped
and pinned across all hosts.
The pip_install role now uses constraints for
the initial get-pip [1], so we can also remove
the list of pip pins from group_vars.
We remove pip, setuptools and wheel from the
requirements.txt to allow the packages on the
host to be installed in the bootstrap without
forcing a change of pip/setuptools/wheel at the
same time (which causes failures in some
circumstances).
[1] https://review.openstack.org/483905
Change-Id: Ida84fb6bb726e1332f0e29ade51b67a5721f0785
5f7000e185