Inclusion check failing

[lpw25]

A bug report from @jordwalke:

module type OneSig = sig
  type t
  val oneValue: t -> string
end

module type TwoSig = sig
  type t
  val twoValue: t -> int
end

let hasBothOneAndTwo (implicit OneImpl: OneSig) (implicit TwoImpl: TwoSig with type t = OneImpl.t) (o : OneImpl.t) =
  let twoValue = string_of_int (TwoImpl.twoValue o) in
  let oneValue = OneImpl.oneValue o in
    oneValue ^ twoValue

implicit module HasBothForAbstractFloat: sig
  type t
  val create: unit -> t
  val oneValue: t -> string
  val twoValue: t -> int
end = struct
  type t = float
  let create () = 4.4
  let oneValue = string_of_float
  let twoValue = int_of_float
end

let abstractFloat = HasBothForAbstractFloat.create ()

let _ = hasBothOneAndTwo abstractFloat

gives the error:

Error: Signature mismatch:
       ...
       Type declarations do not match:
         type t
       is not included in
         type t = HasBothForAbstractFloat.t
       File "[5]", line 7, characters 7-8: Expected declaration
       File "[5]", line 17, characters 7-8: Actual declaration
Characters 681-697:
  let _ = hasBothOneAndTwo abstractFloat
          ^^^^^^^^^^^^^^^^

It seems that, for some reason, the final inclusion check ends up checking the strengthened version of the module type (the one including "type t = HasBothForAbstractFloat.t") against the unstrengthed version (the one with just "type t").