Fixed a bug that caused savepoint rollback to not properly

set object state when objects implemented _p_invalidate methods
that reloaded ther state (unghostifiable objects).

https://bugs.launchpad.net/zodb/+bug/428039

src/ZODB/Connection.py

@@ -1143,8 +1143,9 @@ class Connection(ExportImport, object):
         self._abort()
         self._registered_objects = []
         src = self._storage
-        self._cache.invalidate(src.index)
+        index = src.index
         src.reset(*state)
+        self._cache.invalidate(index)
 
     def _commit_savepoint(self, transaction):
         """Commit all changes made in savepoints and begin 2-phase commit

src/ZODB/tests/testConnectionSavepoint.py

@@ -154,6 +154,34 @@ We simply rely on the underlying storage method.
     False
 """
 
+class SelfActivatingObject(persistent.Persistent):
+
+    def _p_invalidate(self):
+        super(SelfActivatingObject, self)._p_invalidate()
+        self._p_activate()
+
+def testInvalidateAfterRollback():
+    """\
+The rollback used to invalidate objects before resetting the TmpStore.
+This caused problems for custom _p_invalidate methods that would load
+the wrong state.
+
+    >>> import ZODB.tests.util
+    >>> db = ZODB.tests.util.DB()
+    >>> connection = db.open()
+    >>> root = connection.root()
+
+    >>> root['p'] = p = SelfActivatingObject()
+    >>> transaction.commit()
+    >>> p.foo = 1
+    >>> sp = transaction.savepoint()
+    >>> p.foo = 2
+    >>> sp2 = transaction.savepoint()
+    >>> sp.rollback()
+    >>> p.foo  # This used to wrongly return 2
+    1
+    """
+
 def tearDown(test):
     transaction.abort()