Delete whole object when its last revision is deleted.

Also, call prune() when deleting object, to reuse its btree instance.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@2461 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/storage/database/btree.py

@@ -422,13 +422,14 @@ class BTreeDatabaseManager(DatabaseManager):
         except KeyError:
             pass
         else:
-            if serial is None:
-                del obj[oid]
-            else:
+            if serial is not None:
                 try:
                     del tserial[serial]
                 except KeyError:
                     pass
+            if serial is None or not tserial:
+                prune(obj[oid])
+                del obj[oid]
 
     def getTransaction(self, tid, all=False):
         tid = util.u64(tid)