make "help" refuse arguments for now

Since they are otherwise silently ignored.

main.go

@@ -237,6 +237,9 @@ func mainErr(args []string) error {
 	// If we recognize an argument, we're not running within -toolexec.
 	switch command, args := args[0], args[1:]; command {
 	case "help":
+		if len(args) > 0 {
+			return fmt.Errorf("the help command does not take arguments")
+		}
 		return flag.ErrHelp
 	case "version":
 		if len(args) > 0 {

testdata/scripts/help.txt

@@ -1,25 +1,29 @@
 ! garble
 stderr -count=1 'Usage'
-stderr 'garble \[flags\] build'
+stderr 'garble \[garble flags\] command'
 ! stderr 'usage: go build'
 ! stdout .
 
 ! garble -h
-stderr 'garble \[flags\] build'
+stderr 'garble \[garble flags\] command'
 ! stdout .
 
 ! garble help
-stderr 'garble \[flags\] build'
+stderr 'garble \[garble flags\] command'
+! stdout .
+
+! garble help foo bar
+stderr 'does not take arguments'
 ! stdout .
 
 ! garble build -h
-stderr 'garble \[flags\] build'
+stderr 'garble \[garble flags\] command'
 ! stderr 'usage: go build'
 ! stdout .
 
 ! garble -badflag
 stderr 'flag provided but not defined'
-stderr 'garble \[flags\] build'
+stderr 'garble \[garble flags\] command'
 ! stdout .
 
 ! garble badcmd