Use released version of persistent.

buildout.cfg

 [buildout]
 develop = .
-parts = test scripts
-
+parts =
+    test
+    scripts
 versions = versions
-# Temporary, until 'persistent' is released to PyPI.
-find-links = .
 
 [versions]
 zc.recipe.testrunner = 1.3.0
+persistent = 4.0.0
 
 [test]
 recipe = zc.recipe.testrunner
-eggs = ZODB3 [test]
+eggs =
+    persistent
+    ZODB3 [test]
 initialization = 
   import os, tempfile
   try: os.mkdir('tmp')
@@ -21,5 +23,7 @@ defaults = ['--all']
 
 [scripts]
 recipe = zc.recipe.egg
-eggs = ZODB3 [test]
+eggs =
+    persistent
+    ZODB3 [test]
 interpreter = py