Sync pip with Mac OS updates

from blog lmno.lol @alvaro, | ↗ original
My pip installation recently broke after a Mac OS update. $ pip Traceback (most recent call last): File "/usr/local/bin/pip\n", line 5, in from pkg_resources import load_entry_point File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources.py\n", line 2793, in working_set.require(__requires__) ...