Make error handling more obvious

Again, the code looks a little more like a middle-schooler's code. But
that just makes it easier to understand and maintain.

cobra_test.go

@@ -768,7 +768,7 @@ func TestRootNoCommandHelp(t *testing.T) {
 
 func TestRootUnknownCommand(t *testing.T) {
 	r := noRRSetupTest("bogus")
-	s := "Error: unknown command \"bogus\"\nRun 'cobra-test help' for usage.\n"
+	s := "Error: unknown command \"bogus\"\nRun 'cobra-test --help' for usage.\n"
 
 	if r.Output != s {
 		t.Errorf("Unexpected response.\nExpecting to be:\n %q\nGot:\n %q\n", s, r.Output)