[bug] firewall isup return 1 is not an error

bitmask-root firewall isup uses the return code to signal if the
firewall is up or not. We should not report it as an error.

- Resolves: #179

pkg/standalone/launcher_linux.go

@@ -193,13 +193,12 @@ func runBitmaskRoot(arg ...string) error {
 	arg = append([]string{bitmaskRoot}, arg...)
 
 	out, err := exec.Command("pkexec", arg...).Output()
-	if err != nil {
+	if err != nil && arg[2] != "isup" {
 		log.Println("Error while running bitmask-root:")
 		log.Println("args: ", arg)
 		log.Println("output: ", string(out))
-		return err
 	}
-	return nil
+	return err
 }
 
 func bitmaskRootPath() (string, error) {