Run develop on the buildout package too.

git-svn-id: http://svn.zope.org/repos/main/zc.buildout/trunk@70451 62d5b8a3-27da-0310-9561-8e5933582275

buildout.cfg

 [buildout]
-develop = zc.recipe.egg_ zc.recipe.testrunner
+develop = zc.recipe.egg_ zc.recipe.testrunner .
 parts = test py
 find-links = http://download.zope.org/distribution