**Apache Airflow version**:

master

**Kubernetes version (if you are using kubernetes)** (use `kubectl version`):

**Environment**: breeze

**What happened**:

This DAG
```python
from airflow import models
from airflow.operators.dummy_operator import DummyOperator
from airflow.utils.dates import days_ago

with models.DAG("test", start_date=days_ago(1), schedule_interval=None,) as dag:
    t1 = DummyOperator(task_id="t1")
    t2 = DummyOperator(task_id="t2")
    t1 >> t2
```

is rendering like that:

<img width="1374" alt="Screenshot 2020-08-27 at 19 59 41" src="https://user-images.githubusercontent.com/9528307/91478403-11d7fb00-e8a0-11ea-91d0-d7d578bcb5a2.png">

**What you expected to happen**:

I expect to see same relations as defined in DAG file

**How to reproduce it**:

Render the example DAG from above.


**Anything else we need to know**:

I'm surprised by this bug 👀 

airflow/www/views.py
"""Autocomplete."""
        query = unquote(request.args.get('query', ''))
        if not query:
            wwwutils.json_response([])
        
        dag_ids_query = session.query(DagModel.dag_id.label('item')).filter(  
            ~DagModel.is_subdag, DagModel.is_active,
            DagModel.dag_id.ilike('%' + query + '%'))  
        owners_query = session.query(func.distinct(DagModel.owners).label('item')).filter(
            ~DagModel.is_subdag, DagModel.is_active,
            DagModel.owners.ilike('%' + query + '%'))  
        
        status = flask_session.get(FILTER_STATUS_COOKIE)
        if status == 'active':
            dag_ids_query = dag_ids_query.filter(~DagModel.is_paused)
            owners_query = owners_query.filter(~DagModel.is_paused)
        elif status == 'paused':
            dag_ids_query = dag_ids_query.filter(DagModel.is_paused)
            owners_query = owners_query.filter(DagModel.is_paused)
        filter_dag_ids = current_app.appbuilder.sm.get_accessible_dag_ids()
        
        if 'all_dags' not in filter_dag_ids:
            dag_ids_query = dag_ids_query.filter(DagModel.dag_id.in_(filter_dag_ids))
            owners_query = owners_query.filter(DagModel.dag_id.in_(filter_dag_ids))
        
        payload = [row[0] for row in dag_ids_query.union(owners_query).limit(10).all()]
        return wwwutils.json_response(payload)