Adjusted the test so that it also works when you're testing with an older setuptools version and there's a new one on pypi.
In that case, the _call_easy_install call will really try to install setuptools first and execute other code paths than the test cares for.
A cleaner way does not seem possible as the easy_install code is really intertwined.

git-svn-id: http://svn.zope.org/repos/main/zc.buildout/trunk@106059 62d5b8a3-27da-0310-9561-8e5933582275