Merge rev 37777 from 3.4 branch.

Part of Collector 1860 (the other part is in Zope).

There's no possiblity of rollback here, so no need to insist that the
data manager support rollbacks.

NEWS.txt

@@ -166,13 +166,14 @@ BTrees
   was removed from ZODB years ago.
 
 
-What's new in ZODB3 3.4.1b3?
+What's new in ZODB3 3.4.1b4?
 ============================
 Release date: DD-MMM-2005
 
 Following are dates of internal releases (to support ongoing Zope 2
 development) since ZODB 3.4's last public release:
 
+- 3.4.1b4 07-Aug-2005
 - 3.4.1b3 04-Aug-2005
 - 3.4.1b2 02-Aug-2005
 - 3.4.1b1 26-Jul-2005
@@ -200,6 +201,10 @@ Savepoints
   marked a savepoint as invalid after its first use.  The implementation has
   been repaired, to match the docs.
 
+- (3.4.1b4) Collector 1860:  use an optimistic savepoint in ExportImport
+  (there's no possiblity of rollback here, so no need to insist that the
+  data manager support rollbacks).
+
 ZEO client cache
 ----------------
 

src/ZODB/ExportImport.py

@@ -72,7 +72,7 @@ class ExportImport:
         return_oid_list = []
         self._import = f, return_oid_list
         self._register()
-        t.savepoint()
+        t.savepoint(optimistic=True)
         # Return the root imported object.
         if return_oid_list:
             return self.get(return_oid_list[0])