title: ansible : get roles from playbook in a subfolder
body: <p>I have this tree:</p>
  
  <pre><code>├── plays
  │   ├── ansible.cfg
  │   ├── playbook_01.yml
  │   ├── playbook_02.yml
  │   └── playbook_03.yml
  ├── README.rst
  ├── roles
  │   ├── role_A
  │   │   ├── files
  │   │   └── tasks
  │   │       └── main.yml
  │   └── role_B
  │       ├── files
  │       └── tasks
  │           └── main.yml
  ├── serverlist
  │   ├── client1_serverlist_prod
  │   ├── client1_serverlist_test
  │   ├── client1_serverlist_train
  │   ├── client2_serverlist_prod
  │   ├── client2_serverlist_test
  │   └── client2_serverlist_train
  └── vagrant
      └── Vagrantfile
  </code></pre>
  
  <p>With ansible.cfg in play folder::</p>
  
  <pre><code>$ cat plays/ansible.cfg
  [defaults]
  roles_path=../roles/
  $
  </code></pre>
  
  <p>I call from vagrant the ansible.playbook::</p>
  
  <pre><code>$ grep playbook vagrant/Vagrantfile
  ansible.playbook = "../plays/playbook_01.yml
  </code></pre>
  
  <p>on playbook_01.yml::</p>
  
  <pre><code>$ cat plays/playbook_01.yml
  - hosts: vagrant
    vars:
      user: fox
      home: /home/fox
    roles:
      - role_B
  </code></pre>
  
  <p>with role_B::</p>
  
  <pre><code>$ cat roles/role_B/tasks/main.yml
  ---
  - name: Create user group
    group: name={{ user }} state=present
  
  - name: Create home directory for user
    file: state=directory path={{ home }} group=www-data owner={{ user }}
  $
  </code></pre>
  
  <p>But ansible when only went to see roles in play folder, I get this error::</p>
  
  <pre><code>vagrant$ vagrant provision
  ==&gt; vagrant: Running provisioner: ansible...
  PYTHONUNBUFFERED=1 ANSIBLE_HOST_KEY_CHECKING=false ANSIBLE_FORCE_COLOR=true
  ANSIBLE_SSH_ARGS='-o UserKnownHostsFile=/dev/null -o IdentitiesOnly=yes -o
  ForwardAgent=yes -o ControlMaster=auto -o ControlPersist=60s' ansible-playbook
  --user=vagrant --connection=ssh --timeout=30 --limit='vagrant'
  --inventory-file=/home/luis/lab/sandbox/akd-iac/stack/vagrant/.vagrant/provisioners/ansible/inventory
  --sudo -vvvv ../plays/playbook_01.yml
  ERROR: cannot find role in
  ~/stack/plays/roles/role_B or
  ~/stack/plays/role_B or /etc/ansible/roles/role_B
  Ansible failed to complete successfully. Any error output should be
  visible above. Please fix these errors and try again.
  vagrant$
  </code></pre>