message: use push_str instead of multiple calls to arg()
diff: @@ -35,29 +35,24 @@ pub fn npm_adduser(
  always_auth: bool,
  auth_type: Option<String>,
  ) -> Result<(), Error> {
  - let status = Command::new("npm")
  - .arg("adduser")
  - .arg(if let Some(registry) = registry {
  - format!("--registry {}", registry)
  - } else {
  - String::from("")
  - })
  - .arg(if let Some(scope) = scope {
  - format!("--scope {}", scope)
  - } else {
  - String::from("")
  - })
  - .arg(if always_auth == true {
  - String::from("--always_auth")
  - } else {
  - String::from("")
  - })
  - .arg(if let Some(auth_type) = auth_type {
  - format!("--auth_type {}", auth_type)
  - } else {
  - String::from("")
  - })
  - .status()?;
  + let mut args = String::new();
  +
  + if let Some(registry) = registry {
  + args.push_str(&format!(" --registry={}", registry))
  + }
  + if let Some(scope) = scope {
  + args.push_str(&format!(" --scope={}", scope))
  + }
  +
  + if always_auth == true {
  + args.push_str(" --always_auth")
  + }
  +
  + if let Some(auth_type) = auth_type {
  + args.push_str(&format!(" --auth_type={}", auth_type))
  + }
  +
  + let status = Command::new("npm").arg("adduser").arg(args).status()?;
  if !status.success() {
  bail!("Adding registry user account failed");
  