title: RefreshControl sometimes does not hide and acts weirdly on iOS
body: <p>after upgrading from <code>react-native@0.26</code> activity indicator of <code>RefreshControl</code> sometimes appears in right corner of <code>ScrollView</code> on iOS.
  I am using RefreshControl as correctly as documentation says:</p>
  
  <pre><code>...
  &lt;ScrollView
    style={styles.container}
    refreshControl={
      &lt;RefreshControl
        refreshing={this.state.isRefreshing}
        onRefresh={this.onPullToRefresh}
      /&gt;
    }&gt;
    &lt;View&gt;
      ...
    &lt;/View&gt;
  &lt;/ScrollView&gt;
  ...
  </code></pre>
  
  <p>and here is what sometimes happening while not refreshing:</p>
  
  <p><a href="https://i.stack.imgur.com/uBMmH.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uBMmH.png" alt="enter image description here"></a></p>
  
  <p>Now I am running <code>react-native@0.30.0</code> and this indicator is still annoying me.</p>
  
  <p>Am I the only who faces this issue?</p>