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 <module>
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 <module>
working_set.require(__requires__)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources.py\n", line 673, in require
needed = self.resolve(parse_requirements(requirements))
File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources.py\n", line 576, in resolve
raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: pip==1.1
Updating my pip installation fixes the break:
$ sudo easy_install -U pip