Example playbook with roles for ansible bug "Tags on tasks in dependent roles are not honoured"

gistfile1.txt

play.yml:- hosts: localhost
play.yml:  gather_facts: false
play.yml:  roles:
play.yml:      - a
play.yml:  
a/meta/main.yml:---
a/meta/main.yml:dependencies:
a/meta/main.yml:    - ab
a/tasks/debug.yml:---
a/tasks/debug.yml:# tasks file for a
a/tasks/debug.yml:- debug:
a/tasks/debug.yml:
a/tasks/main.yml:---
a/tasks/main.yml:# tasks file for a
a/tasks/main.yml:- include: debug.yml
a/tasks/main.yml:  tags: sometag
a/tasks/main.yml:
ab/meta/main.yml:---
ab/meta/main.yml:dependencies:
ab/meta/main.yml:    - abc
ab/tasks/debug.yml:---
ab/tasks/debug.yml:# tasks file for ab
ab/tasks/debug.yml:- debug:
ab/tasks/debug.yml:
ab/tasks/main.yml:---
ab/tasks/main.yml:# tasks file for a
ab/tasks/main.yml:- include: debug.yml
ab/tasks/main.yml:  tags: sometag
ab/tasks/main.yml:
abc/tasks/debug.yml:---
abc/tasks/debug.yml:# tasks file for abc
abc/tasks/debug.yml:- debug:
abc/tasks/debug.yml:
abc/tasks/main.yml:---
abc/tasks/main.yml:# tasks file for a
abc/tasks/main.yml:- include: debug.yml
abc/tasks/main.yml:  tags: sometag
abc/tasks/main.yml: