It looks like the problem has been introduced by recent changes to dump more stuff as "constraints". pg_dump is careful to dump indexes before constraints --- but the latter category now includes not only foreign key constraints, but unique/primary constraints, and those will all end up sorted by pg_constraint OID, it looks like. I think that should work anyway, most of the time, but clearly after an OID wraparound it's possible for the OID-order heuristic to fail. So we need to tweak pg_dump to categorize the different kinds of constraints separately.
regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend