Pip and Python disagree on module location

Question

OK, this is just strange. I am helping a colleague on a Mac (Yosemite), running the shipped Python executable in /usr/bin/python (2.7.10). I used the shipped easy_install to install pip (9.0.1), which was deposited in /usr/local/bin with a shebang line of #!/usr/bin/python. I then used pip to install some modules, including six, only to find out that pip and python somehow disagree about that module's version:

Tail of pip install -vvv -U six:

Installed version (1.10.0) is most up-to-date (past versions: 0.9.0, 0.9.1, 0.9.2, 1.0.0, 1.1.0, 1.2.0, 1.3.0, 1.4.0, 1.4.1, 1.5.0, 1.5.1, 1.5.2, 1.6.0, 1.6.1, 1.7.0, 1.7.1, 1.7.2, 1.7.3, 1.8.0, 1.9.0, 1.10.0)
Requirement already up-to-date: six in /Library/Python/2.7/site-packages

Output of python -c 'import six; print six.__version__':

1.4.1

Relevant locations:

$ type pip
pip is /usr/local/bin/pip
$ type python
python is /usr/bin/python
$ head -n 1 $(type -p pip)
#!/usr/bin/python

$PYTHONPATH is not set in the environment. But they are still looking in different places. As you can see from the pip output, it's looking/storing in /Library/Python/2.7/site-packages/. But if I loop over sys.path, the first place I find six is in /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/.

So where's the disconnect?

Answer 1

The issue turned out to be the order of the load path. On my Sierra machine (where I verified that I was able to install a new six for the default /usr/bin/python), /Library/Python/2.7/site-packages comes before /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python in sys.path. But on the coworker's machine, /Library/Python/2.7/site-packages is the very last entry, coming after the Extras folder, so the pip-installed version is masked by the system install.

I suspect this is a problem with the Yosemite Python installation that was fixed by Sierra, but in any case I can see no easy fix. So the options are to install a separate Python instance (my preference; I usually use pyenv anyway) or manually set PYTHONPATH to put site-packages out front. Or upgrade to a newer macOS, I suppose.

Thanks to everyone for the help figuring this out.