Assertion failure at standby promotion

Hi,

I got the following assertion failure when I promoted the standby.

2013-05-04 00:12:31 JST sby1 LOG: received promote request
2013-05-04 00:12:31 JST sby1 FATAL: terminating walreceiver process
due to administrator command
2013-05-04 00:12:31 JST sby1 LOG: redo done at 0/6FFE038
2013-05-04 00:12:31 JST sby1 LOG: last completed transaction was at
log time 2013-05-04 00:12:25.878909+09
2013-05-04 00:12:31 JST sby1 LOG: selected new timeline ID: 2
2013-05-04 00:12:31 JST sby1 LOG: archive recovery complete
2013-05-04 00:12:31 JST sby1 LOG: checkpoint starting:
TRAP: FailedAssertion("!(sentPtr <= sendTimeLineValidUpto)", File:
"walsender.c", Line: 1465)
2013-05-04 00:12:31 JST sby1 LOG: autovacuum launcher started

The way to reproduce this is:

1. Create one master A, one standby B, and one cascade standby C.
2. Run pgbench -i -s 10
3. Promote the standby B before pgbench -i finishes

Regards,

--
Fujii Masao