**Description**

For a DAG that looks like this:

```
A >> B
```

If A fails, B goes into "upstream_failed" state. If a user then marks A "success", B will remain in "upstream_failed" state. It will not automatically start running. This scenario often happens if the failure of A is dealt with outside of Airflow and the user does not want Airflow to run A again. But he usually expect Airflow to run B after A is marked "success".

**Use case / motivation**

After A is marked "success", its downstream tasks B should be cleared automatically and get ready to be scheduled. To avoid changing this behaviour completely, there can be a toggle button next to "Success" that lets the user decide if he wants Airflow to automatically clear downstream tasks that are in "upstream_failed" state.
airflow/www/views.py
'base_date': max_date or timezone.utcnow(),
                'num_runs': num_runs,
            }
        )
        chart.buildcontent()
        cum_chart.buildcontent()
        s_index = cum_chart.htmlcontent.rfind('});')
        cum_chart.htmlcontent = (
            cum_chart.htmlcontent[:s_index]
            + "$( document ).trigger('chartload')"
            + cum_chart.htmlcontent[s_index:]
        )
        return self.render_template(
            'airflow/duration_chart.html',
            dag=dag,
            root=root,
            form=form,
            chart=Markup(chart.htmlcontent),
            cum_chart=Markup(cum_chart.htmlcontent),
        )
    @expose('/tries')
    @auth.has_access(
        [
            (permissions.ACTION_CAN_READ, permissions.RESOURCE_DAG),
            (permissions.ACTION_CAN_READ, permissions.RESOURCE_TASK_INSTANCE),
        ]
    )
    @action_logging
    @provide_session
    def tries(self, session=None):