install error thinks pythonpath is empty

Question

I am trying to install the scikits.nufft package here I download the zip file, unpack and cd to the directory. It contains a setup.py file so I run

python setup.py install

but it gives me the following error related to my PYTHONPATH

sudo python setup.py install
sudo: unable to resolve host Lenovo
/usr/local/lib/python2.7/dist-packages/distribute-0.6.31-py2.7.egg/setuptools/command/install_scripts.py:3: UserWarning: Module dap was already imported from None, but /usr/lib/python2.7/dist-packages is being added to sys.path
  from pkg_resources import Distribution, PathMetadata, ensure_directory
running install
Checking .pth file support in /usr/local/lib/python2.7/site-packages/
/usr/bin/python -E -c pass
TEST FAILED: /usr/local/lib/python2.7/site-packages/ does NOT support .pth files
error: bad install directory or PYTHONPATH

You are attempting to install a package to a directory that is not
on PYTHONPATH and which Python does not read ".pth" files from.  The
installation directory you specified (via --install-dir, --prefix, or
the distutils default setting) was:

    /usr/local/lib/python2.7/site-packages/

and your PYTHONPATH environment variable currently contains:

    ''

Here are some of your options for correcting the problem:

* You can choose a different installation directory, i.e., one that is
  on PYTHONPATH or supports .pth files

* You can add the installation directory to the PYTHONPATH environment
  variable.  (It must then also be on PYTHONPATH whenever you run
  Python and want to use the package(s) you are installing.)

* You can set up the installation directory to support ".pth" files by
  using one of the approaches described here:

  http://packages.python.org/distribute/easy_install.html#custom-installation-locations

Please make the appropriate changes for your system and try again.

It seems to think the path is empty but when I check my path I get,

echo $PYTHONPATH
/usr/local/lib/python2.7/site-packages:/home/david/PYTHON

Does anyone know why it might think the path is empty?? or have any other ideas as to what may be wrong here. Thanks, Dave

Answer 1

After Aya's comment above I found similar resolved problem here and got it to run by adding

Defaults    env_keep += "PYTHONPATH"

to the sudoers file. Ta, Dave