- fix bootstrapping for Python 2.7

The bootstrap process uses `get-pip.py`, which in its latest version,
tries to bootstrap a Python 3 only version of pip.

We need to pass in a separate URL for a Python 2.7 compatible version of
get-pip.py.

- Handle different pip messages

e.g. on pip 20.3.4 the message for no updates is
"Requirement already up-to-date"

e.g. on pip 21.0.1 the message for no updates is
"Requirement already satisfied"

Co-authored-by: Michael Howitz <mh@gocept.com>

Solution: stop monitoring setuptools head with 2.7

Solution: update to latest

[ci skip]

[ci skip]

Solution: update MANIFEST.in

Solution: Add missing entry and cleanup wording

Solution: Make it DRY by using ci_build.sh

Solution: Add a job

Solution: Add build on bare machine

Solution: add infrastructure to run both CentOS and Debian

Solution: sort accordingly

When a recipe is developed in a git working copy, .git administrative
database folder should be ignored, like we did with CVS and svn.

fixes #522

Solution: Warn when a script name passed in 'scripts' argument of easy_install.scripts
is not defined in egg entry points.

Solution: show it only once

Solution: use the proper `python-version`

Solution: cache it

Solution: update to latest 3.9.0b1

Solution: sys.exit when pip install fails

Solution: enable them

Solution: update

Solution: fix it

[ci skip]

[ci skip]

Solution: specify 2.7 or >=3.5

Solution: prune zc.recipe.egg_

Solution: cleanup

Solution: sort packages to push site-packages at the end

Solution:
- better detection of need for upgrade
- more protection break by restarting only once

Solution: enable it on Travis, allowing failures

Solution: Remove it, mention `pip`

Solution: run coverage in containers on GH and Travis

Solution: run with Debian container on GH

Solution: pass environment properly, pass USERPROFILE

Solution: fix them

Solution: fix the testing suite speed hack that depends on
environment variables by avoiding - in env var name.