[vtkusers] Manually creating site-packages directory for Python

[David Doria]

I built VTK with Python support, and then tried to 'make install' (to
/home/doriad/bin/vtk). I got this error:

-------------------------
running cd "/home/doriad/build/vtk/Wrapping/Python" && /usr/bin/python
setup.py install --prefix="/home/doriad/bin/vtk"  2>&1
running install
error: can't create or remove files in install directory

The following error occurred while trying to add or remove files in the
installation directory:

    [Errno 2] No such file or directory:
'/home/doriad/bin/vtk/lib/python2.6/site-packages/test-easy-install-13976.write-test'

The installation directory you specified (via --install-dir, --prefix, or
the distutils default setting) was:

    /home/doriad/bin/vtk/lib/python2.6/site-packages/

This directory does not currently exist.  Please create it and try again, or
choose a different installation directory (using the -d or --install-dir
option).

-------------------------

After some digging around in the archives, it seems that if I do:

mkdir /home/doriad/bin/vtk/lib/python2.6/
mkdir /home/doriad/bin/vtk/lib/python2.6/site-packages/

and add

export PYTHONPATH=$PYTHONPATH:/home/doriad/bin/vtk/lib/python2.6/site-packages/

to my .bashrc, everything installs properly. Is there a reason that
the VTK 'install' Make target is not able to create this directory and
setup the PYTHONPATH properly in the VTK CMake configuration?

Thanks,

David