This change is a small simplification that simply creates the
egg_info directory in the egg_base location; it's a minor
cleanup that results in some read and it helps with
read-only directories (the egg_info directory is uncontrollable).

In some cases (specifically when pip imports this module in a virtualenv),
pkg_resources can already be imported, causing setuptools to load
entry_points from an older version. Here, we re-initialize the master
working set to fix the case where the entry points from an older
setuptools are loaded.

commands: dist_info: say something!

The dist_info command did not say anything like other
commands did. This gives some more helpful information.

Expect failure on macOS 10.13 and other operating systems where writing latin-1 encoded filenames is prohibited. Fixes #1169.

Tests: Run `python -m pip` instead of plain `pip`

Clean up resource warnings during tests

tests: make sure some essential tests are run

See https://bugs.python.org/issue2751