**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
flask_session[FILTER_STATUS_COOKIE] = status
            arg_status_filter = status
        dags_per_page = PAGE_SIZE
        current_page = get_int_arg(arg_current_page, default=0)
        start = current_page * dags_per_page
        end = start + dags_per_page
        
        filter_dag_ids = current_app.appbuilder.sm.get_accessible_dag_ids()
        with create_session() as session:
            
            dags_query = session.query(DagModel).filter(
                ~DagModel.is_subdag, DagModel.is_active
            )
            
            if arg_search_query:
                dags_query = dags_query.filter(
                    DagModel.dag_id.ilike('%' + arg_search_query + '%') |  
                    DagModel.owners.ilike('%' + arg_search_query + '%')  
                )
            if arg_tags_filter:
                dags_query = dags_query.filter(DagModel.tags.any(DagTag.name.in_(arg_tags_filter)))
            if 'all_dags' not in filter_dag_ids:
                dags_query = dags_query.filter(DagModel.dag_id.in_(filter_dag_ids))
                
            all_dags = dags_query
            active_dags = dags_query.filter(~DagModel.is_paused)
            paused_dags = dags_query.filter(DagModel.is_paused)
            is_paused_count = dict(
                all_dags.with_entities(DagModel.is_paused, func.count(DagModel.dag_id))
                .group_by(DagModel.is_paused).all()