title: ASAuthorizationAppleIDRequest with name and mail scope returns nil values
body: <p>I'm implementing Sign in with Apple and noticed that the <code>email</code> and <code>fullName</code> properties of the returned <code>ASAuthorizationAppleIDCredential</code> are only filled on the very first Sign-In for this Apple ID. On all subsequent Sign-Ins those properties are nil.</p>
  
  <p>Is this a bug on iOS 13 or expected behaviour?</p>
  
  <p>Here is the code I'm using to start the request:</p>
  
  <pre><code>@available(iOS 13.0, *)
  dynamic private func signInWithAppleClicked() {
      let request = ASAuthorizationAppleIDProvider().createRequest()
      request.requestedScopes = [.fullName, .email]
  
      let controller = ASAuthorizationController(authorizationRequests: [request])
      controller.delegate = self
      controller.presentationContextProvider = self
      controller.performRequests()
  }
  </code></pre>
  
  <p>I'm receiving the credential in this delegate method:</p>
  
  <pre><code>public func authorizationController(controller: ASAuthorizationController, didCompleteWithAuthorization authorization: ASAuthorization) {
      guard let credential = authorization.credential as? ASAuthorizationAppleIDCredential else { return }
  
      let userIdentifier = credential.user
      let token = credential.identityToken
      let authCode = credential.authorizationCode
      let realUserStatus = credential.realUserStatus
      let mail = credential.email // nil
      let name = credential.fullName // nil
  }
  </code></pre>