message: [bugfix] visualization flickers when rerunning query
  When hitting the Query button in the explore view, the previous chart
  gets shown (flaskhed quickly) between the moment where the loading
  spinner goes away and the new chart show up. This fix seems to prevent
  this.
diff: @@ -79,7 +79,7 @@ class Chart extends React.PureComponent {
  handleRenderSuccess() {
  const { actions, chartStatus, chartId, vizType } = this.props;
  - if (chartStatus !== 'rendered') {
  + if (['loading', 'rendered'].indexOf(chartStatus) < 0) {
  actions.chartRenderingSucceeded(chartId);
  }
  