Fixes #1208: Improved exception message of pkg_resources.ResolutionError

Add another test demonstrating that if requirements are declared in a non-deterministic order, they may appear in the metadata in non-deterministic order. Ref #458.

use ssl.create_default_context and SNI if available

Build meta: fixes and cleanups

Fix test command

support `setup_requires` in setup.cfg

python 3 bdist_egg --exclude-source-files __pycache__ issue