title: onCompleted handler not firing with Apollo Client Query
body: <p>I'm having issues getting the onCompleted callback to fire when executing an Apollo Client query.</p>
  
  <p>The query has no problems running, and it returns the results I would expect, but the <em>onCompleted</em> handler never fires. I have tried multiple things:</p>
  
  <ul>
  <li>a) I have tried using HOC instead of the React  component (see
  comment at end of gist)</li>
  <li>b) I've tried invalidating the cache and setting fetchPolicy to 'network-only'</li>
  <li>I've tried setting the handler to "async"</li>
  </ul>
  
  <p>There is an Github open issue related to what I'm experiencing, however the people in this thread only experience the problem when loading from cache. I'm experiencing the callback not firing <strong>all the time.</strong> <a href="https://github.com/apollographql/react-apollo/issues/2177" rel="nofollow noreferrer">https://github.com/apollographql/react-apollo/issues/2177</a></p>
  
  <p>Here is a trimmed example of my code:</p>
  
  <pre class="lang-javascript prettyprint-override"><code>import React from 'react';
  import { graphql, Query } from 'react-apollo';
  import { ProductQuery } from '../../graphql/Products.graphql';
  
  class EditProductVisualsPage extends React.Component {
    constructor() {
      super();
    }
  
    render() {
      const { productId } = this.props;
      return (
        &lt;Query
          query={ProductQuery} 
          variables={{ id: productId }}
          onCompleted={data =&gt; console.log("Hi World")}&gt;
          {({ loading, data: { product } }) =&gt; (
            /* ... */ 
          )}
        &lt;/Query&gt;
      );
    }
  }
  
  export default EditProductVisualsPage;
  
  /*
  export default graphql(ProductQuery, {
    options: props =&gt; ({
      variables: {
        id: props.productId,
      },
      fetchPolicy: "cache-and-network",
      onCompleted: function() {
        debugger;
      },
    }),
  })(EditProductVisualsPage);
  */
  </code></pre>
  
  <p>At this point I'm completely stumped. Any help would be appreciated.</p>
  
  <p><strong>Library versions</strong></p>
  
  <ul>
  <li>react-apollo (2.1.4)</li>
  <li>apollo-client (2.3.1)</li>
  <li>react(16.3.32)</li>
  </ul>