haha, golang compress/gzip wat?

package main

import (
	"bytes"
	"compress/gzip"
	"fmt"
)

func main() {
	data := bytes.Repeat([]byte{0x00}, 64<<18+1)
	for lvl := -2; lvl <= 9; lvl++ {
		var b bytes.Buffer
		w, err := gzip.NewWriterLevel(&b, lvl)
		if err != nil {
			continue
		}
		w.Write(data)
		w.Close()
		fmt.Printf("level %2d: %d bytes\n", lvl, b.Len())
	}
}

Results in

level -2: 2097189 bytes
level -1: 32884 bytes
level  0: 16778522 bytes
level  1: 16628 bytes
level  2: 16628 bytes
level  3: 16627 bytes
level  4: 16627 bytes
level  5: 16627 bytes
level  6: 32884 bytes
level  7: 16304 bytes
level  8: 16304 bytes
level  9: 16304 bytes

Magical level 6 compression I guess