Keepalive-related socket options under FreeBSD 9, 10

Since upgrading FreeBSD from 8 to 9, I've noticed the following messages
showing up in logs when a connection with pgAdmin3 is made:

LOG:  getsockopt(TCP_KEEPCNT) failed: Protocol not available
STATEMENT:  SELECT setting FROM pg_settings WHERE name IN ('autovacuum',
'track_counts')
LOG:  getsockopt(TCP_KEEPIDLE) failed: Protocol not available
STATEMENT:  SELECT setting FROM pg_settings WHERE name IN ('autovacuum',
'track_counts')
LOG:  getsockopt(TCP_KEEPINTVL) failed: Protocol not available
STATEMENT:  SELECT setting FROM pg_settings WHERE name IN ('autovacuum',
'track_counts')

tcp_keepalives_idle, tcp_keepalives_interval, and tcp_keepalives_count
are all set to the default (0), which means "system default".

My guess as to what causes this:

src/backend/libpq/pqcomm.c apparently assumes that if TCP_KEEPIDLE &
friends are defined, then the respective options are readable, but
according to man tcp, that is not the case for FreeBSD 9 (and 10):

TCP_KEEPINIT
This write-only setsockopt(2) option accepts a per-socket
timeout argument of u_int in seconds, for new, non-estab-
lished TCP connections.  For the global default in mil-
liseconds see keepinit in the MIB Variables section fur-
ther down.

As a work-around, I've set the keepalive options to the system defaults
provided by man tcp.