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* 553: egg_info section is now generated in a
deterministic order, matching the order generated
by earlier versions of Python. Except on Python 2.6,
order is preserved when existing settings are present.
* 556: Update to Packaging 16.7, restoring support
for deprecated ``python_implmentation`` marker.
* 555: Upload command now prompts for a password
when uploading to PyPI (or other repository) if no
password is present in .pypirc or in the keyring.