title: @@redux-form/UPDATE_SYNC_ERRORS is unintentionally clearing my _error state
body: <p>I'm setting up form-wide errors pretty much exactly like the <a href="http://redux-form.com/6.5.0/examples/submitValidation/" rel="nofollow noreferrer">Submit Validation Example</a> from the docs.</p>
  
  <p>But unlike the example, my <code>_error</code> object is removed as soon as I do any change in any other form field on my page. On the example page the <code>_error</code> is always shown until the button is pressed again.</p>
  
  <p>Using the Redux dev tools extension in Chrome I see that the action <code>@@redux-form/UPDATE_SYNC_ERRORS</code> is dispatched on the first change I do on any other form field after <code>_error</code> has been set and this action is clearing my <code>_error</code> object in the form state.</p>
  
  <ul>
  <li>How can I control when this action is dispatched?</li>
  <li>Can I make it not clear my <code>_error</code> object?</li>
  </ul>