Forward port from 2.7 branch.

UndoSearch._readnext():  Add the transaction size to the return value.

NEWS.txt

+What's new in ZODB3 3.4a1?
+==========================
+Release date: DD-MMM-2005
+
+-3.4.1a1 DD-MMM-2005
+
+FileStorage.UndoSearch
+----------------------
+
+- (3.4.1a1) The ``_readnext()`` method now returns the transaction size as
+  the value of the "size" key.  Thanks to Dieter Maurer for the patch, from
+  http://mail.zope.org/pipermail/zodb-dev/2003-October/006157.html. "This is
+  very valuable when you want to spot strange transaction sizes via Zope's
+  'Undo' tab".
+
+
 What's new in ZODB3 3.4?
 ========================
 Release date: 09-Jun-2005

src/ZODB/FileStorage/FileStorage.py

@@ -2088,6 +2088,7 @@ class UndoSearch:
         d = {'id': base64.encodestring(tid).rstrip(),
              'time': TimeStamp(tid).timeTime(),
              'user_name': u,
+             'size': tl,
              'description': d}
         d.update(e)
         return d