BUG #6676: checkpointer does not work by SIGINT.

The following bug has been logged on the website:

Bug reference: 6676
Logged by: Tomonari Katsumata
Email address: katsumata.tomonari@po.ntts.co.jp
PostgreSQL version: Unsupported/Unknown
Operating system: RHEL 5.7 x86_64
Description:

Hi,

Now I'm testing the behavior of checkpointer,
and I found a difference with PostgreSQL9.1 behavior.

When I send SIGINT signal to writer process on PostgreSQL9.1,
writer process starts checkpoint.
But, when I send SIGINT signal to checkpointer on PostgreSQL9.2beta2,
checkpointer doesn't start checkpoint.

<PostgreSQL 9.1.3>
change the config file(postgresql.conf) to log information about
checkpoint.
log_checkpoints = on
logging_collector = on

$ psql postgres -c "create table tbl(i int)"
CREATE TABLE

$ psql postgres -c "insert into tbl values(1);"
INSERT 0 1

$ ps faxww | grep postgres | grep "writer process"
19706 ? Ss 0:00 \_ postgres: writer process
19707 ? Ss 0:00 \_ postgres: wal writer process

$ kill -2 19706

<log messages>
LOG: checkpoint starting:
LOG: checkpoint complete: wrote 1 buffers (0.0%); 0 transaction log file(s)
added, 0 removed, 0 recycled; write=0.000 s, sync=0.001 s, total=0.004 s;
sync files=1, longest=0.001 s, average=0.001 s

============
<PostgreSQL 9.2beta2>
change the config file(postgresql.conf) to log information about
checkpoint.
log_checkpoints = on
logging_collector = on

$ psql postgres -c "create table tbl(i int);"
CREATE TABLE

$ psql postgres -c "insert into tbl values(1);"
INSERT 0 1
$ ps faxww | grep checkpointer
11526 pts/3 S+ 0:00 | \_ grep checkpointer
11482 ? Ss 0:00 \_ postgres: checkpointer process

$ kill -2 11482

<no log messages>
============

I know "latch" is introduced on PostgreSQL9.2,
but I'm not sure this is a bug or not.
Is this a desirable behavior of "latch" ?