image/gif: LoopCount changes on round trip #11287

package main

import (
    "bytes"
    "fmt"
    "image/gif"
)

func main() {
    data := []byte("GIF89a000\x00000,0\x00\x00\x00\n\x00" +
        "\n\x00\x80000000\x02\b\xf01u\xb9\xfdal\x05\x00;")
    img, err := gif.DecodeAll(bytes.NewReader(data))
    if err != nil {
        return
    }
    w := new(bytes.Buffer)
    err = gif.EncodeAll(w, img)
    if err != nil {
        panic(err)
    }
    img1, err := gif.DecodeAll(w)
    if err != nil {
        panic(err)
    }
    fmt.Printf("LoopCount: %v -> %v\n", img.LoopCount, img1.LoopCount)
}