Thanks! It is probably worth to apply the same patch at least for the oacs-5-9 branch and the released tar files, since people trying fresh installs of the current OpenACS 5.9 release with PostgreSQL 11 will run into the same problem.
Background: PostgreSQL 11 dropped the "WITH" clause for "CREATE FUNCTION", which was deprecated since PG 7.2. The mentioned problem does not exist for upgrades to PG 11 (except probably for dumps before PG 7.2) but for new installs.
