Looks like version 4.0.0 has been out for a few weeks: https://pypi.python.org/pypi/Pillow/4.0.0
We're at version 4.1.1, now: https://pypi.python.org/pypi/Pillow/4.1.1
i think this report is obsolete as pillow-4.2.1 is in portage tree.