Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

$ go version
go version go1.8 linux/amd64

What operating system and processor architecture are you using (go env)?

$ go env
GOARCH="amd64"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build871485140=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"

What did you do?

Use the Debug function in encoding/gob to try to view a gob. A simplified gob that has the error is here:

package main

import (
	"bytes"
	"encoding/gob"
)

var gobBytes = []byte{0x3, 0x6, 0x0, 0xa}


func main() {
	gob.Debug(bytes.NewReader(gobBytes))
}

(Sorry I can't put this in the playground as you need to build the gob package without the build guard for Debug)

What did you expect to see?

Output of Debug should have been

Start of debugging
10

What did you see instead?

Start of debugging
5

Basically this was being treated as an integer and not an unsigned integer and so decoded with the

y := (x >> 1)
if x&1 != 0 {
   y = ^y
}

integer decoding method.