**This issue tracker is a tool to address bugs in Flask itself.
Please use the #pocoo IRC channel on freenode or Stack Overflow for general
questions about using Flask or issues not related to Flask.**

If you'd like to report a bug in Flask, fill out the template below. Provide
any extra information that may be useful / related to your problem.
Ideally, create an [MCVE](https://stackoverflow.com/help/mcve), which helps us
understand the problem and helps check that it is not caused by something in
your code.

---

### Expected Behavior

Tell us what should happen.

```python
Paste a minimal example that causes the problem.
```

### Actual Behavior

Tell us what happens instead.

```pytb
Paste the full traceback if there was an exception.
```

### Environment

* Python version:
* Flask version:
* Werkzeug version: