title: React navigation return to previous screen immdiately
body: <p>Trying to add navigation to React Native app with Redux and Saga. It work for one screen but when adding AppNavigator like this one it behaves strange</p>
  
  <pre><code>import HomeScreen from '../screens/fake/HomeScreen';
  import LoginScreen from '../screens/fake/LoginScreen';
  import SplashScreen from '../screens/fake/SplashScreen';
  
  export const AppNavigator = createStackNavigator({
    Splash: SplashScreen,
    Home: HomeScreen,
    Login: LoginScreen
  });
  </code></pre>
  
  <p>Each screen is control like this one:
  class HomeScreen</p>
  
  <pre><code> extends React.Component {
    render() {
      return (
        &lt;View&gt;
          &lt;Button
            title="Go to Login"
            onPress={() =&gt; this.props.navigation.navigate('Login')}
          /&gt;
          &lt;Button
            title="Go to Splash"
            onPress={() =&gt; this.props.navigation.navigate('Splash')}
          /&gt;
        &lt;/View&gt;
      );
    }
  };
  </code></pre>
  
  <p>i.e. contains only button that should navigates to another screen. And it does. But after that happens event <code>Navigation/NAVIGATE</code> that return user to previous page.</p>
  
  <p>First event <code>Navigation/NAVIGATE</code> contains correct route key. But second occurence - <code>Navigation/COMPLETE_TRANSITION</code> (more exact: <code>{type: "Navigation/COMPLETE_TRANSITION", key: "StackRouterRoot"}</code>) return user to previous screen.</p>
  
  <p>Any ideas?</p>