Setuptools now uses the 'packaging' package from pkg_resources, unifying the behavior around resolution of that package.

Move vendored packaging module into pkg_resources._vendor, restoring independence of pkg_resources from setuptools. Fixes #311.

Add test making explicit the expectation that pkg_resources shouldn't import setuptools (or be dependent on it in any way). Ref #311.

Silence PEP440Warning by default unless invoking easy_install

Upgrade packaging to 14.5

Add a PEP440Warning to make it easier to silence these warnings

Don't warn on empty non PEP 440 versions