**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
"""View to show records from Connections table"""
    route_base = '/connection'
    datamodel = AirflowModelView.CustomSQLAInterface(Connection)  
    base_permissions = ['can_add', 'can_list', 'can_edit', 'can_delete']
    extra_fields = ['extra__jdbc__drv_path', 'extra__jdbc__drv_clsname',
                    'extra__google_cloud_platform__project',
                    'extra__google_cloud_platform__key_path',
                    'extra__google_cloud_platform__keyfile_dict',
                    'extra__google_cloud_platform__scope',
                    'extra__google_cloud_platform__num_retries',
                    'extra__grpc__auth_type',
                    'extra__grpc__credential_pem_file',
                    'extra__grpc__scopes',
                    'extra__yandexcloud__service_account_json',
                    'extra__yandexcloud__service_account_json_path',
                    'extra__yandexcloud__oauth',
                    'extra__yandexcloud__public_ssh_key',
                    'extra__yandexcloud__folder_id',
                    'extra__kubernetes__in_cluster',
                    'extra__kubernetes__kube_config',
                    'extra__kubernetes__namespace']
    list_columns = ['conn_id', 'conn_type', 'host', 'port', 'is_encrypted',
                    'is_extra_encrypted']
    add_columns = edit_columns = ['conn_id', 'conn_type', 'host', 'schema',
                                  'login', 'password', 'port', 'extra'] + extra_fields
    add_form = edit_form = ConnectionForm
    add_template = 'airflow/conn_create.html'
    edit_template = 'airflow/conn_edit.html'
    base_order = ('conn_id', 'asc')
    @action('muldelete', 'Delete', 'Are you sure you want to delete selected records?',