---
- hosts: all
  remote_user: root
  roles:
    - { role: FGtatsuro.python-requirements }
    - { role: FGtatsuro.ruby }
  tasks:
    - name: root use /bin/bash
      user: name=root shell=/bin/bash
      become: yes

---
- hosts: all
  remote_user: root
  roles:
    - { role: FGtatsuro.python-requirements }
    - { role: FGtatsuro.ruby }
  tasks:
    - name: root use /bin/bash
      command: "chsh -s /bin/bash root"
      become: yes
      changed_when: False

Use command module instead of user module.
Use command module instead of user module.

On Alpine Linux, user/group modules doesn't work well.
