**Apache Airflow version**: 2.1.0

**Browsers**: Chrome and Firefox

**What happened**:

Before upgrading to 2.1.0

![before](https://user-images.githubusercontent.com/14293802/120359517-c1ca1100-c2d5-11eb-95ba-58ccc0a3ac37.png)

After upgrading to 2.1.0

![after](https://user-images.githubusercontent.com/14293802/120359528-c4c50180-c2d5-11eb-8e04-f34846ea2736.png)

**What you expected to happen**:

Show/Edit/Delete under Security -> Users are available

<!-- What do you think went wrong? -->

**How to reproduce it**:

Go to Security -> Users (as an admin of course) 
airflow/www/views.py
dag.can_edit = True
                else:
                    dag_resource_name = permissions.RESOURCE_DAG_PREFIX + dag.dag_id
                    dag.can_edit = (permissions.ACTION_CAN_EDIT, dag_resource_name) in user_permissions
                dag.can_trigger = dag.can_edit and can_create_dag_run
                dag.can_delete = can_delete_dag
            dagtags = session.query(DagTag.name).distinct(DagTag.name).all()
            tags = [
                {"name": name, "selected": bool(arg_tags_filter and name in arg_tags_filter)}
                for name, in dagtags
            ]
            import_errors = session.query(errors.ImportError).order_by(errors.ImportError.id).all()
        for import_error in import_errors:
            flash("Broken DAG: [{ie.filename}] {ie.stacktrace}".format(ie=import_error), "dag_import_error")
        from airflow.plugins_manager import import_errors as plugin_import_errors
        for filename, stacktrace in plugin_import_errors.items():
            flash(
                f"Broken plugin: [{filename}] {stacktrace}",
                "error",
            )
        num_of_pages = int(math.ceil(num_of_all_dags / float(dags_per_page)))
        state_color_mapping = State.state_color.copy()
        state_color_mapping["null"] = state_color_mapping.pop(None)
        page_title = conf.get(section="webserver", key="instance_name", fallback="DAGs")
        return self.render_template(
            'airflow/dags.html',
            dags=dags,
            current_page=current_page,
            search_query=arg_search_query if arg_search_query else '',
            page_title=page_title,