型拡張でオーバーロードすると式木が取れない

gistfile1.fs

// fsiで

type Hoge() =
  member this.Piyo(i: int) = "piyo1"
  member this.Piyo(s: string) = "piyo2"

let f () =
  <@ (fun (h: Hoge) -> h.Piyo(42)) @>;; // <- ここと、

type Hoge with
  member this.Foo(i: int) = "foo1"
  member this.Foo(s: string) = "foo2"

let g () =
  <@ (fun (h: Hoge) -> h.Foo(42)) @>;; // <- ここのダブルセミコロンを取ると動く

f () // OK
g () // NG
;;