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.

Solution: Add a GH workflow

Solution: monkeypatch `setuptools.packageIndex`
with code from `pip._internal`.

Because it depends on `pip._internal`, it is fragile.
As a first defense against breakage, imports are protected.
In case they would fail, buildout still works.

Solution: Use `pip install`

The meat of the change is in src/zc/buildout/easy_install.py

Some tests had to be refactored a bit to make them more robust.

`tox` is removed to avoid issues due to sharing the same directory
between different virtual environments; `Makefile` enriched to make
per python virtual envs depend on source files.

No need to be afraid of default Python install as we depend on `pip`.
`bootstrap.py` is gone as not needed anymore.

by patching `pkg_resources.Distribution`.

Run Travis tests in CentOS container.

Tests under Python 2.7 are temporarily disabled.

Centos container on Github Actions

register combine and report with atexit

[ci skip]

[ci skip]

[actions] fix scripts and setuptools-master workflows

build for 2.7 was broken by new release of more-itertools

Use Github Actions for smoke tests

to generate scripts

run buildout and check which files are downloaded
and which eggs are installed

Fix simple typo: expecially -> especially

Fixes #484.

Fix typo.

[ci skip]

[ci skip]

Avoid DeprecationWarning: 'U' mode is deprecated (Version 2)

Now the deprecation warning itself is fixed, we no longer need to
suppress it to have the tests pass.

Add a RENormalizer so the easy_install.txt will be happy with scripts
generated on Python 2 (using open(..., 'U')) and on Python 3 (using just
open(...)).

This was suggested by @sallner.

Python 3.7 began warning about open's 'U' mode. Universal newline mode (newline=None) is default in Python 3 so avoid specifying it on Python 3.