[BUG] govc host.info is always writing to os.stdout instead of the writer passed to Write

[markrexwinkel]

Describe the bug

I am using the govc commands in my own cli. I basically repeating the steps done by cli.Run().
Now as I understand it, each implemented command has a Write() function that should write the output to the passed in writer.

govc host.info is always writing to os.stdout instead of the writer passed to Write().

I know it would be better to use govmomi directly but the govc commands where a quick way to implement the functionality I needed.

To Reproduce
Steps to reproduce the behavior:

main.go:

package main

import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"io"
	"os"

	"github.com/vmware/govmomi/govc/cli"
	"github.com/vmware/govmomi/govc/flags"
	_ "github.com/vmware/govmomi/govc/host"
	"github.com/vmware/govmomi/vim25/types"
)

func main() {
	name := "host.info"
	cmd, ok := cli.Commands()[name]
	if !ok {
		panic(fmt.Sprintf("command not found %q", name))
	}

	fs := flag.NewFlagSet("", flag.ContinueOnError)
	fs.SetOutput(io.Discard)

	ctx := context.Background()

	if id := os.Getenv("GOVC_OPERATION_ID"); id != "" {
		ctx = context.WithValue(ctx, types.ID{}, id)
	}

	var buf bytes.Buffer

	outFlag, ctx := flags.NewOutputFlag(ctx)
	outFlag.Out = &buf

	cmd.Register(ctx, fs)

	defer func() {
		_ = clientLogout(ctx, cmd)
	}()

	if err := fs.Parse(os.Args[1:]); err != nil {
		panic(err)
	}

	if err := cmd.Process(ctx); err != nil {
		panic(err)
	}

	if err := cmd.Run(ctx, fs); err != nil {
		panic(err)
	}

	if buf.Len() == 0 {
		panic("Expected buffer length > 0")
	}
}

func clientLogout(ctx context.Context, cmd cli.Command) error {
	type logout interface {
		Logout(context.Context) error
	}

	if l, ok := cmd.(logout); ok {
		return l.Logout(ctx)
	}

	return nil
}

Make sure you set the GOVC_URL, GOVC_USERNAME and GOVC_PASSWORD environment variables.

Expected behavior
Output of the host.info command should be written to the writer passed in to the OutputFlag.

Affected version
govc 0.29.0

Screenshots/Debug Output

Output of the main.go described above is:

Name:              esxi.lab.internal
  Path:            /lab.internal/host/esxi.lab.internal/esxi.lab.internal
  Manufacturer:    Micro-Star International Co., Ltd.
  Logical CPUs:    8 CPUs @ 2904MHz
  Processor type:  Intel(R) Core(TM) i7-10700F CPU @ 2.90GHz
  CPU usage:       684 MHz (2.9%)
  Memory:          65453MB
  Memory usage:    21644 MB (33.1%)
  Boot time:       2022-11-02 14:00:30.47428 +0000 UTC
  State:           connected
panic: Expected buffer length > 0

[github-actions]

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