builder/vmware: fix local output dir exists check

builder/vmware/output_dir.go

@@ -23,7 +23,7 @@ type localOutputDir struct {
 
 func (d *localOutputDir) DirExists() (bool, error) {
 	_, err := os.Stat(d.dir)
-	return err == nil, err
+	return err == nil, nil
 }
 
 func (d *localOutputDir) MkdirAll() error {

builder/vmware/step_prepare_output_dir.go

@@ -66,8 +66,10 @@ func (s *stepPrepareOutputDir) outputDir(state multistep.StateBag) (dir OutputDi
 
 	switch d := driver.(type) {
 	case OutputDir:
+		log.Printf("Using driver as the OutputDir implementation")
 		dir = d
 	default:
+		log.Printf("Using localOutputDir implementation")
 		dir = new(localOutputDir)
 	}