Merged oacs-5-6 to HEAD. HEAD now installs and passes all core tests. There may still be some lingering problems due to my screwing up the oacs-5-6 branch earlier, I'll be looking into this later.
Changed db_flush to use the ns_cache names pattern construct to only return the matching names, rather than return all names then flush those that match the pattern (I was unaware that names took a pattern arg, how embarrasing!)