Ok, I think I found it: the query being executed is package_object_attribute_list.attributes_select which lives in acs-subsite/tcl/package-procs-oracle.xql and this query was modified by Ben as follows:
Index: package-procs-oracle.xql
===================================================================
RCS file: /cvsroot/openacs-4/packages/acs-subsite/tcl/package-procs-oracle.xql,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -r1.3 -r1.4
--- package-procs-oracle.xql 2001/08/03 21:09:20 1.3
+++ package-procs-oracle.xql 2001/11/21 05:20:31 1.4
@@ -128,7 +128,7 @@
start with t.object_type=:start_with
connect by prior t.object_type = t.supertype) t
where a.object_type = :object_type
- and t.object_type = a.ancestor_type $storage_clause
+ and t.object_type = a.object_type $storage_clause
order by type_level
If you put back the ancestor_type then it works, just like the PG one. Looks like a mistake to me. Ben, can you shed any light on this?