[Zope] Python Path?

Hi all After installing more than one Zope on my machine I noticed the following: The one installation's Python path also appears in the other installation's. Is there an easy way to make sure that a Zope installation acts as if it was installed on a clean machine without Python? I would like to have an installation like that since I have been surprised previously by import errors etc. when installing Zope on a client's machine and (wrongly) thinking that I had all the modules at hand, only to find out the installation only worked on my machine due to another Zope having a specific module on the sys.path. I know I can hard-code sys.path in the z2.py file, but it doesn't feel that elegant to me. Any suggestions? Thanks Etienne