New formula for Taxi. A timesheet tool

This works for me on a clean Mavericks VM with system Python (Python 2.7.5, setuptools 0.6c12) and with Homebrew Python (Python 2.7.8, setuptools 5.4.2). I'm interested in understanding why this error happens. Do you get more information about the error if you `brew install -vd taxi` with the `--single-version-externally-managed` option in place? Which directory is missing?