Something is fairly whacko about shutdown in CVS HEAD

I'm seeing two sets of shutdown messages, and apparently a second
shutdown checkpoint being forced, during a normal database stop:

2007-06-30 14:21:00 EDT 9644 LOG: received smart shutdown request
2007-06-30 14:21:00 EDT 9647 LOG: shutting down
2007-06-30 14:21:00 EDT 9647 LOG: checkpoint starting: shutdown immediate
2007-06-30 14:21:00 EDT 9647 LOG: checkpoint complete: wrote 23 buffers (0.6%); 0 transaction log file(s) added, 0 removed, 0 recycled; write=0.003 s, sync=0.178 s, total=0.237 s
2007-06-30 14:21:00 EDT 9647 LOG: database system is shut down
2007-06-30 14:21:00 EDT 9644 LOG: background writer process (PID 9647) exited with exit code 0
2007-06-30 14:21:00 EDT 9644 LOG: terminating any other active server processes
2007-06-30 14:21:00 EDT 9644 LOG: all server processes terminated; reinitializing
2007-06-30 14:21:00 EDT 9654 LOG: database system was shut down at 2007-06-30 14:21:00 EDT
2007-06-30 14:21:01 EDT 9655 LOG: shutting down
2007-06-30 14:21:01 EDT 9655 LOG: checkpoint starting: shutdown immediate
2007-06-30 14:21:01 EDT 9655 LOG: checkpoint complete: wrote 0 buffers (0.0%); 0 transaction log file(s) added, 0 removed, 0 recycled; write=0.000 s, sync=0.000 s, total=0.041 s
2007-06-30 14:21:01 EDT 9655 LOG: database system is shut down

I haven't looked for the cause yet but I suspect it's got something to
do with this patch:
http://archives.postgresql.org/pgsql-committers/2007-06/msg00285.php
Either that or somebody else broke it recently.

regards, tom lane