The same thing happened to me. I also thought that the new version requiring PostgreSQL8.X (from HEAD and oacs-5-2) didn't need the changes to the postgres.conf file, but it does.
I did what the howto says and it worked fine. (I didn't create the bitfromint4 function, though)
https://openacs.org/xowiki/en/How_to_install_in_Postgres_8%2e1%2ex