Possible bug ansible dev 2 - tasks are executed muliple times when including other plays

masterplay.yml

---
- include: play_a.yml
- include: play_b.yml

  # to run (include trailing comma!):
  # $ ansible-playbook masterplay.yml -i 127.0.0.1,

play_a.yml

---
- hosts: 127.0.0.1
  connection: local
  name: play a

  vars:
    foo2: bar

  tasks:
  - name: the task in play a
    debug: msg="{{ foo2 }}"

play_b.yml

---
- hosts: 127.0.0.1
  connection: local
  name: play b

  vars:
    foo: bar

  tasks:
  - name: the task in play b
    debug: msg="{{ foo }}"