golang.org/dl/gotip: needs to add its go binary to PATH

[dmitshur]

The fix for #28103 was applied to the golang.org/dl/internal/version package, which fixed the problem for all golang.org/dl/go... packages other than golang.org/dl/gotip.

I tested with a small program:

main.go source

package main

import (
	"fmt"
	"log"
	"os/exec"
)

func main() {
	goBin, err := exec.LookPath("go")
	if err != nil {
		log.Fatalln(err)
	}
	fmt.Println(goBin)
	out, err := exec.Command(goBin, "version").Output()
	if err != nil {
		log.Fatalln(err)
	}
	fmt.Printf("%s version: %s", goBin, out)
}

$ go run ./main.go
/usr/local/go/bin/go
/usr/local/go/bin/go version: go version go1.13.4 darwin/amd64
$ go1.12.9 run ./main.go
/Users/dmitshur/sdk/go1.12.9/bin/go
/Users/dmitshur/sdk/go1.12.9/bin/go version: go version go1.12.9 darwin/amd64
$ gotip run ./main.go
/usr/local/go/bin/go
/usr/local/go/bin/go version: go version go1.13.4 darwin/amd64

gotip run ./main.go should be printing:

/Users/dmitshur/sdk/gotip/bin/go
/Users/dmitshur/sdk/gotip/bin/go version: go version devel +ad7ce391 Mon Nov 11 18:00:18 2019 +0000 darwin/amd64

[gopherbot]

Change https://golang.org/cl/206537 mentions this issue: gotip: add $GOROOT/bin to $PATH before starting go binary