Hot standby v5 patch assertion failure

Trying out a few different scenarios I ran across this:

1/ Setup master and replica with replica using pg_standby
2/ Create a new database ("bench" in my case)
3/ Initialize pgbench schema size 100
4/ Run with 2 clients and 10000 transactions
5/ Replica gets assertion failure

This is Postgres head from 2nd Nov (NZST) with v5 patch applied on
Freebsd 7.1 Prerelease.
Here is the last few log entries:

DEBUG: executing restore command "pg_standby -l -d -s 2 -t
/tmp/pgsql.trigger.5439 /data0/pgarchive/8.4 00000001000000000000006F
pg_xlog/RECOVERYXLOG 000000010000000000000069 2>>standby.log"
LOG: restored log file "00000001000000000000006F" from archive
DEBUG: RecordKnown xid 6999 parent 0 slot 99 latestObsvXid 6998
firstXid t firstSubXid f markSubtrans f
CONTEXT: xlog redo update: rel 1663/16384/16397; tid 141396/12; new
158829/8
DEBUG: start recovery xid = 6999 lsn = 0/6F001708
CONTEXT: xlog redo update: rel 1663/16384/16397; tid 141396/12; new
158829/8
DEBUG: removing recovery locks: slot 99
CONTEXT: xlog redo commit: 2008-11-03 11:57:18.958241+13
DEBUG: RecordKnown xid 7000 parent 0 slot 98 latestObsvXid 6999
firstXid t firstSubXid f markSubtrans f
CONTEXT: xlog redo update: rel 1663/16384/16397; tid 32133/24; new
158828/58
DEBUG: start recovery xid = 7000 lsn = 0/6F0055C8
CONTEXT: xlog redo update: rel 1663/16384/16397; tid 32133/24; new
158828/58
DEBUG: removing recovery locks: slot 98
CONTEXT: xlog redo commit: 2008-11-03 11:57:18.963507+13
DEBUG: removing recovery locks: slot 99
CONTEXT: xlog redo commit: 2008-11-03 11:57:18.967145+13
DEBUG: RecordKnown xid 7002 parent 0 slot 98 latestObsvXid 7000
firstXid t firstSubXid f markSubtrans f
CONTEXT: xlog redo update: rel 1663/16384/16397; tid 9614/62; new 158828/59
DEBUG: start recovery xid = 7002 lsn = 0/6F012EE4
CONTEXT: xlog redo update: rel 1663/16384/16397; tid 9614/62; new 158828/59
TRAP: FailedAssertion("!(!((UnobservedXids[index]) != ((TransactionId)
0)))", File: "procarray.c", Line: 2037)
DEBUG: reaping dead processes
LOG: startup process (PID 12600) was terminated by signal 6: Abort trap
LOG: aborting startup due to startup process failure
DEBUG: proc_exit(1)
DEBUG: shmem_exit(1)
DEBUG: exit(1)

regards

Mark