Oh, I think I see the problem:
8.0 pg_regress:
if [ "$unix_sockets" = no ]; then
postmaster_options="$postmaster_options -c listen_addresses=$hostname"
else
postmaster_options="$postmaster_options -c listen_addresses=''"
fi
8.1 pg_regress:
if [ "$unix_sockets" = no ]; then
postmaster_options="$postmaster_options -c listen_addresses=$hostname"
else
postmaster_options="$postmaster_options -c listen_addresses="
fi
regards, tom lane