This was a very nasty problem that took me quite a while to find. Apparently, the problem exists only on sites updating since many versions, but not on fresh installs of oacs-5-2 from the repository. The same problem exist(ed) on openacs.org, where i first updated openacs to the latest fixes of openacs 5.2. But this did not help either.
Apparently the long running sites have "only" 4 versions of content_revision__new (do a \df content_revision__new), while new installs have 7.
To fix the problem, source from psql packages/acs-content-repository/sql/postgresql/content-revision.sql
and ignore the errors at the end. Do one more ::xowiki::fix_all_package_ids, and you are set.
It looks as if there is somewhere a missing update script.