**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 Airflow Configurations"""
    default_view = 'conf'
    @expose('/configuration')
    @has_access
    def conf(self):
        """Shows configuration."""
        raw = request.args.get('raw') == "true"
        title = "Airflow Configuration"
        subtitle = AIRFLOW_CONFIG
        
        if conf.getboolean("webserver", "expose_config"):
            with open(AIRFLOW_CONFIG, 'r') as file:
                config = file.read()
            table = [(section, key, value, source)
                     for section, parameters in conf.as_dict(True, True).items()
                     for key, (value, source) in parameters.items()]