Merged -r105475:105584 svn+ssh://reinout@svn.zope.org/repos/main/zc.buildout/branches/reinout_distribute_upgrade_check
This is the fix for an infinite recursion when updating Distribute.
Solved by using the available setuptools/distribute for easy_installing the Distribute tgz instead of searching for it, which tries to install, which searches...

git-svn-id: http://svn.zope.org/repos/main/zc.buildout/trunk@105585 62d5b8a3-27da-0310-9561-8e5933582275