Diff doesn't return difference b/w nil of slice and empty slice

[motomux]

package main

import (
	"fmt"
	"reflect"

	"github.com/kr/pretty"
)

func main() {
	var s1 []int
	s2 := []int{}
	fmt.Println(pretty.Diff(s1, s2))
	fmt.Printf("Is %#v deep equal to %#v ? %v\n", s1, s2, reflect.DeepEqual(s1, s2))
}

output

[]
Is []int(nil) deep equal to []int{} ? false