I guess you could work around that by having null in the version column for the active/latest row. Then your queries become 'where version is null' if you want to skip superseded rows. You could then use partial indexes (where version is null) to handle unique constraints etc.

EDIT I hadn't finished reading the article, so I didn't see that they were using triggers and the history table. Using the approach I outlined you could keep everything in the same table (if you were that way inclined).