refactor: remove all calls to common.NewShellCmd

At this point, the only usage of go-sh should be by plugin trigger calls.

plugins/registry/subcommands.go

@@ -3,6 +3,7 @@ package registry
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"io"
 	"os"
 	"strings"
@@ -35,25 +36,23 @@ func CommandLogin(server string, username string, password string, passwordStdin
 		server = "docker.io"
 	}
 
-	command := []string{
-		common.DockerBin(),
-		"login",
-		"--username",
-		username,
-		"--password-stdin",
-		server,
-	}
-
 	buffer := bytes.Buffer{}
 	buffer.Write([]byte(password + "\n"))
 
-	loginCmd := common.NewShellCmd(strings.Join(command, " "))
-	loginCmd.Command.Stdin = &buffer
-	if !loginCmd.Execute() {
-		return errors.New("Failed to log into registry")
+	result, err := common.CallExecCommand(common.ExecCommandInput{
+		Command:      common.DockerBin(),
+		Args:         []string{"login", "--username", username, "--password-stdin", server},
+		Stdin:        &buffer,
+		StreamStderr: true,
+	})
+	if err != nil {
+		return fmt.Errorf("Unable to run docker login: %w", err)
+	}
+	if result.ExitCode != 0 {
+		return fmt.Errorf("Unable to run docker login: %s", result.StderrContents())
 	}
 
-	_, err := common.CallPlugnTrigger(common.PlugnTriggerInput{
+	_, err = common.CallPlugnTrigger(common.PlugnTriggerInput{
 		Trigger:     "post-registry-login",
 		Args:        []string{server, username},
 		StreamStdio: true,