The update of the bricks variables of an app is not working

The endpoint to override the bricks variables  inside the  `app.yaml`  is not working


Example:

```
PUT /v1/apps/dXNlcjpjb3B5LW9mLWJsaW5raW5nLWxlZC1mcm9tLWFyZHVpbm8tY2xvdWQ/bricks/arduino:arduino_cloud

{"variables":{"ARDUINO_DEVICE_ID":"asdf","ARDUINO_SECRET":"asfd"}}
```

Response
```
 {"details":"error while creating or updating brick"}
``