Client.Do will not uncompress response body

clientDoGzip.go

package main

// run this file with `go run clientDoGzip.go, and then file tmp.out to verify body is gzipped

import "compress/gzip"
import "net/http"
import "fmt"
import "io"
import "log"
import "os"

func main() {
    url := "http://bash.cyberciti.biz/wp-content/themes/bashshell/custom/images/headerbg.gif"
    req, err := http.NewRequest("GET", url, nil)
    if err != nil {
        log.Fatal(err)
    }
    req.Header.Set("Accept-Encoding", "gzip")
    if err != nil {
        log.Fatal(err)
    }
    client := &http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        log.Fatal(err)
    }
    defer resp.Body.Close()
    for k, v := range resp.Header {
        fmt.Println(k+":", v)
    }

    var r io.Reader

    switch req.Header.Get("Accept-Encoding") {
    case "gzip":
        r, err = gzip.NewReader(resp.Body)
        if err != nil {
            log.Fatal(err)
        }
    default:
        r = resp.Body
    }

    fd, err := os.Create("tmp.out")
    if err != nil {
        log.Fatal(err)
    }
    _, err = io.Copy(fd, r)
    if err != nil {
        log.Fatal(err)
    }
}