DistributionNotFound error after upgrading pip
Question: In reading about virtualenv
[here](http://www.virtualenv.org/en/latest/index.html) I realized I didn't
have pip 1.3+, so I ran `pip install --upgrade pip` and now when I run `pip
--version` i get the following:

    
    
    Traceback (most recent call last):
      File "/usr/local/bin/pip", line 5, in <module>
        from pkg_resources import load_entry_point
      File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/distribute-0.6.34-py2.7.egg/pkg_resources.py", line 2807, in <module>
        parse_requirements(__requires__), Environment()
      File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/distribute-0.6.34-py2.7.egg/pkg_resources.py", line 594, in resolve
        raise DistributionNotFound(req)
    pkg_resources.DistributionNotFound: pip==1.2.1
    

If it helps, or is at all relevant, my `$PATH` looks like this:

    
    
    /usr/local/bin:/usr/local/share/python:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/local/git/bin
    

Also, `which pip` gives me `/usr/local/bin/pip`.

Not sure what to do about the error. Thanks.


Answer: ### The brutal way:

Assuming you are using homebrew for Mac (because I see /usr/local/Cellar), I
suggest to

  * remove (or backup) `/usr/local/lib/python2.7`, and 
  * `brew rm python && brew install python`. 

This will definitely install pip 1.3.3 alongside of python. Your distribute
will also be 0.6.35.

### The soft way:

From `/usr/local/lib/python2.7/site-packages` just remove:

  * `easy-install.pth`
  * `pip-1.2.1-py2.7.egg` _or other versions of pip you have._
  * `distribute-0.6.34-py2.7.egg` _or other versions_

Then, `brew rm python && brew install python`. This will leave all your other
bindings from brew and installed stuff intact. Python, pip and distribute will
be replaced with up-to-date versions.

### additionally:

Please check that you don't have a distribute or setuptools or pip located in
`/Library/Python/2.7/site-packages`. That dir is re-used by all python 2.7
versions (brewed or from OS X) and will interferre with the pip/distribute
already installed by Homebrew.

