'NoneType' object has no attribute 'context' when executing chalice deploy

While executing:

`chalice deploy --no-autogen-policy --stage beta`

I get this error: 'NoneType' object has no attribute 'context'

I have narrowed it down to a single line of code in my application.

```python
def param_value(name):
stage = app.current_request.context['stage']
return stage_param_value(stage, name)
```

If I comment out the line that retrieves the stage from the current_request and replace it with
```python
stage = 'beta'
```

then chalice deploy executes successfully.

Start with the application code containing param_value and reproduce the issue with `chalice deploy --no-autogen-policy --stage beta`. Trace why the current request context is unavailable during deployment; done means deployment succeeds without replacing the stage lookup with a hardcoded value.

Written by the indexing model from the issue text.