title: GIDSignIn returns "Keychain error"
body: <p>I'm implementing sign in with Google plus. The implementation is basically copied from examples from <a href="https://developers.google.com/identity/sign-in/ios/sign-in">Developer Google</a>.
  When I login for the first time all works fine. But if I then logout using </p>
  
  <pre><code> [[GIDSignIn sharedInstance] signOut];
  </code></pre>
  
  <p>next time I login in I get the </p>
  
  <pre><code>Error Domain=com.google.GIDSignIn Code=-2 "keychain error"
  </code></pre>
  
  <p>Please advice what can be done in this situation. 
  Thanks</p>