I wanted to let you know that I just released the latest version of catkin_pip.
After about a year working on it on and off, I ended up with a reliable way to use pip from catkin.
It will be in the next indigo & kinetic sync.
It is a set of cmake scripts to enable you to use usual python packages in ROS directly, without modification.
Python packages that follow Python Packaging User Guide only need a CMakeLists.txt and a package.xml, and you are ready to use them with catkin (build for devel, install, and as ROS packages) .
This makes depending on python packages much easier (no need to fork => less maintenance effort), and enables deploying existing python packages as ROS packages via a Third Party Release.
More details in the documentation : http://docs.ros.org/kinetic/api/catkin_pip/html/
I advise you try it out, if the basic catkin workflow doesn’t mix well with your python code.