Cannot use rclone sft backend with "ask_password"

[callegar]

I have an rclone backend configured that uses sftp and employs the ask_password option to ask for the user ssh password interactively. This works just fine with rclone alone (e.g. rclone ls backend), but fails if the backend is used in rustic.

Specifically rustic appears to hang.

1. Is this expected?
2. Would it be possible to propagate the rclone password prompt via rustic?
3. If not, would it be possible to have rustic use a timeout and deliver an informative error message for this case?