You may need to add a symbolic link for your installation. If you've installed Python3.4, for example, on a Debian-based OS, you may need to run the following command before running the setup script:
sudo ln -s /usr/bin/python3.4 /usr/bin/python
If that doesn't work and you continue to receive the same error message as before, there may be an issue with your Python installation and it might be worth uninstalling and later reinstalling it.
Jess @ Tyk