Why I cannot prompt for a variable that will be shared by multiple plays (ansible 1.6.5)

Question

I have distilled a playbook that has three plays. The goal is to collect the database password from a prompt in one play and then use the same password in the other two plays.

Answer 1

I ended up taking user3037143 answer for my localhost sudo password problem:

---
- hosts: localhost
  tags:
    - always
  vars_prompt:
    - name: sudo_password
      prompt: "Sudo password for localhost ONLY"
  tasks:
    - set_fact: ansible_become_password={{ sudo_password }}
      no_log: true

Now it's shared between every include playbooks I have.

I'm on ansible > 2.