When profiling a simple buildout with 10 parts with identical and
large working sets, this resulted in a decrease of run time from
93.411 to 15.068 seconds, about a 6 fold improvement.  To see the
benefit be sure to run without any increase in verbosity ("-v"
option).

git-svn-id: http://svn.zope.org/repos/main/zc.buildout/trunk@124059 62d5b8a3-27da-0310-9561-8e5933582275