Bump version: 40.7.2 → 40.7.3

Revert to using a copy of splituser from Python 3.8.

Revert to using a copy of splituser from Python 3.8. Using urllib.parse.urlparse is clumsy and causes problems as reported in #1663 and #1668. Alternative to #1499 and fixes #1668.

Bugfix/1663 restore port

Ensure port is included in package-index

Ensure a specified port in package_index isn't lost in the parse/unparse of the URL when auth is present. Fixes #1663.

Prefer native strings on Python 2 when reading config files.

tests: minor cleanup

Disallow parent path traversal in resource paths, part 1 (deprecation)

Setuptools will install licenses if included in setup.cfg

improve encoding handling for `setup.cfg`

tests: temporary pin pip to fix the Python 2.7 job

Given that the config file parsing functionality is unlikely to change upstream, just incorporate the functionality directly.