Log Message:
The package uses the "python" executable for building the python bits. \ 
 If it
isn't present in the package build sandpit it may reach out and use a possibly
unmanaged version of python.  On Linux that might be some base system copy of
python, which would only be the same version by chance.

If it happens to be, say, python 2.6 - but Pkgsrc is defaulting to python 2.7,
then the installed files will have the wrong filenames, the PLIST won't match,
and the build will fail (not to mention that the built files may well be
incompatible with the intended python anyway).

Having the "python" tool in the sandpit solves this problem.