struct fields are not indirected correctly for SetYAML

The following program illustrates the problem. The encoding/json package does the right thing here.
I would expect to see the "set yaml called correctly" panic.

package main
import (
 "fmt"
 "launchpad.net/goyaml"
 "encoding/json"
)

type Foo struct {
 S Bar
}

type Bar int

func (b *Bar) SetYAML(tag string, value interface{}) bool {
 panic("set yaml called correctly")
}

func (b *Bar) UnmarshalJSON([]byte) error {
 panic("unmarshal json called correctly")
}

func main() {
 var foo Foo
 err := goyaml.Unmarshal([]byte("S: 345"), &foo)
 fmt.Printf("yaml err: %v\n", err)

 err = json.Unmarshal([]byte(`{"S": 345}`), &foo)
 fmt.Printf("json err: %v\n", err)
}