The query was correct before, MySQL seems to be a bit weird with deletes and joins.
The original problem here looks to be something different. The trace shows he is using hsqldb which should have caused it to use the hsqldb specific query. Instead it appears to be trying to use the general query with the weird MySQL specific syntax.
OF-789 doesn't seem to fix the underlying problem, it just replaces the general query with one which works in hsqldb.
Now it's broken under MySQL.