Exception raised during compilation

[jonludlam]

The following causes an exception

module type Creators_base = sig
  type ('a, _, _) t
  type (_, _, _) concat

  include sig
      type ('a, 'b, 'c) t

      val concat : (('a, 'p1, 'p2) t, 'p1, 'p2) concat -> ('a, 'p1, 'p2) t
    end
    with type ('a, 'b, 'c) t := ('a, 'b, 'c) t
end

module type S0_with_creators_base = sig
  type t

  include Creators_base with type ('a, _, _) t := t and type ('a, _, _) concat := t
end

The exception and backtrace are the same here as for #930 - maybe related?