Revert inappropriate checkin.

The new text wasn't more accurate than the text it
replaced.  I'll add more words, but on the 3.5 branch
(where it belongs), and then merge that to the trunk.

src/transaction/_transaction.py

@@ -362,7 +362,7 @@ class Transaction(object):
         elif deprecation_wng:
             from ZODB.utils import deprecated37
             deprecated37("subtransactions are deprecated; use "
-                         "transaction.savepoint(optimistic=True) instead of "
+                         "transaction.savepoint() instead of "
                          "transaction.commit(1)")
 
         if self._savepoint2index:
@@ -370,7 +370,7 @@ class Transaction(object):
 
         if subtransaction:
             # TODO deprecate subtransactions
-            self._subtransaction_savepoint = self.savepoint(optimistic=True)
+            self._subtransaction_savepoint = self.savepoint(1)
             return
 
         if self.status is Status.COMMITFAILED: