Usage/Description/ArgsUsage correctly copied when using subcommand

command.go

@@ -230,11 +230,9 @@ func (c Command) startApp(ctx *Context) error {
 		app.HelpName = app.Name
 	}
 
-	if c.Description != "" {
-		app.Usage = c.Description
-	} else {
-		app.Usage = c.Usage
-	}
+	app.Usage = c.Usage
+	app.Description = c.Description
+	app.ArgsUsage = c.ArgsUsage
 
 	// set CommandNotFound
 	app.CommandNotFound = ctx.App.CommandNotFound

help.go

@@ -64,7 +64,7 @@ OPTIONS:
 // cli.go uses text/template to render templates. You can
 // render custom help text by setting this variable.
 var SubcommandHelpTemplate = `NAME:
-   {{.HelpName}} - {{.Usage}}
+   {{.HelpName}} - {{if .Description}}{{.Description}}{{else}}{{.Usage}}{{end}}
 
 USAGE:
    {{.HelpName}} command{{if .VisibleFlags}} [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}