[Python] pip installing in global site-packages instead of virtualenv

Using pip3 to install a package in a virtualenv causes the package to be installed in the global site-packages folder instead of the one in the virtualenv folder. Here's how I set up Python3 and virtualenv on OS X Mavericks (10.9.1):

I installed Python3 using Homebrew:

ruby -e "$(curl -fsSL https://raw.github.com/Homebrew/homebrew/go/install)"
brew install python3 --with-brewed-openssl


Changed the $PATH variable in .bash_profile; added the following line:

export PATH=/usr/local/bin:$PATH


Running which python3 returns /usr/local/bin/python3 (after restarting the shell).

Note: which python3 still returns /usr/bin/python though.

Installed virtualenv using pip3:

pip3 install virtualenv


Next, create a new virtualenv and activate it:

virtualenv testpy3 -p python3
cd testpy3
source bin/activate


Note: if I don't specify -p python3, pip will be missing from the bin folder in the virtualenv.

Running which pip and which pip3 both return the virtualenv folder:

/Users/kristof/VirtualEnvs/testpy3/bin/pip3


Now, when I try to install e.g. Markdown using pip in the activated virtualenv, pip will install in the global site-packages folder instead of the site-packages folder of the virtualenv.

pip install markdown


Running pip list returns:

Markdown (2.3.1)
pip (1.4.1)
setuptools (2.0.1)
virtualenv (1.11)


Contents of /Users/kristof/VirtualEnvs/testpy3/lib/python3.3/site-packages:

__pycache__/
_markerlib/
easy_install.py
pip/
pip-1.5.dist-info/
pkg_resources.py
setuptools/
setuptools-2.0.2.dist-info/


Contents of /usr/local/lib/python3.3/site-packages:

Markdown-2.3.1-py3.3.egg-info/
__pycache__/
easy-install.pth
markdown/
pip-1.4.1-py3.3.egg/
setuptools-2.0.1-py3.3.egg
setuptools.pth
virtualenv-1.11-py3.3.egg-info/
virtualenv.py
virtualenv_support/


As you can see, the global site-packages folder contains Markdown, the virtualenv folder doesn't.

Note: I had Python2 and Python3 installed before on a different VM (followed these instructions) and had the same issue with Python3; installing packages in a Python2 based virtualenv worked flawlessly though.

Any tips, hints, … would be very much appreciated.

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