[Distutils] Ignoring site-packages when running zc.buildout tests

[Ross Patterson]

I have python-setuptools installed through my OS and zc.buildout
installed with easy_install.  I'd like to be able to ignore these when
running the zc.buildout tests (or tests for other projects that handle
distributions) so that the system packages don't interfere with the
testing environment.

Any ideas?  Should the zc.buildout tests be modified or should my
system?

Ross