I patched the files:
sql/postgresql/workflow-case-package-body.sql:2
tcl/workflow-procs-postgresql.xql:2
and uploaded the bug/patch:
https://openacs.org/bugtracker/openacs/bug?bug_number=188
I only changed the plpgsql function names, and a grep over the whole packages directory showed that no other packages used the plpgsql functions directly.