make undo method not fail if a SN get disconnected

git-svn-id: https://svn.erp5.org/repos/neo/branches/prototype3@585 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/client/app.py

@@ -684,7 +684,10 @@ class Application(object):
                 continue
 
             self.local_var.txn_info = 0
-            self._askStorage(conn, protocol.askTransactionInformation(transaction_id))
+            try:
+                self._askStorage(conn, protocol.askTransactionInformation(transaction_id))
+            except NEOStorageConnectionFailure:
+                continue
 
             if self.local_var.txn_info == -1:
                 # Tid not found, try with next node
@@ -694,7 +697,7 @@ class Application(object):
             else:
                 raise NEOStorageError('undo failed')
 
-        if self.local_var.txn_info == -1:
+        if self.local_var.txn_info in (-1, 0):
             raise NEOStorageError('undo failed')
 
         oid_list = self.local_var.txn_info['oids']