Changing the directory in a subshell is not working

[Maks1mS]

Example:

package main

import (
	"context"
	"os"
	"strings"

	"mvdan.cc/sh/v3/interp"
	"mvdan.cc/sh/v3/syntax"
)

func main() {
	ctx := context.Background()
	r, _ := interp.New(
		interp.Dir("/opt"),
		interp.StdIO(os.Stdin, os.Stdout, os.Stderr),
	)
	file, _ := syntax.NewParser().Parse(strings.NewReader("echo $PWD"), "")
	r.Run(ctx, file)

	sub := r.Subshell()
	interp.Dir("/")(sub)
	sub.Run(ctx, file)
}

Output:

/opt
/opt

Expected:

/opt
/

May be is related with #1007