Krikri::VarsPrompt
vars_prompt: - questions asked once, before the play runs, whose
answers become play variables.
Real Ansible only actually PROMPTS on a terminal. With stdin piped or
closed it does not read the input at all: it falls back to the
entry's default:, or to None when there is none (verified against
ansible-core 2.19.4 - piping "bob" to a prompt with
default: admin still yields admin). That is what makes the keyword
safe in automation, and it is reproduced here.