Ansible Roles are not namespaces

####### first, define two roles, red and blue, each which
####### define the variable color to be, well, red or blue.

==> roles/red/tasks/main.yml <==
- name: red test
  command: echo $color

==> roles/red/vars/main.yml <==
color: red

==> roles/blue/tasks/main.yml <==
- name: blue test
  command: echo $color

==> roles/blue/vars/main.yml <==
color: blue

######## define a playbook with the two roles

[bowe@catbus ansible]$ head color.yml
- hosts: localhost
  roles:
    - red
    - blue

######## and run it.  Both commands echo 'blue' :(.

[bowe@catbus ansible]$ ANSIBLE_NOCOWS=1 ansible-playbook -v color.yml

PLAY [localhost] **************************************************************

GATHERING FACTS ***************************************************************
ok: [localhost]

TASK: [red test] **************************************************************
changed: [localhost] => {"changed": true, "cmd": ["echo", "blue"], "delta": "0:00:00.001402", "end": "2013-08-03 15:41:52.397388", "item": "", "rc": 0, "start": "2013-08-03 15:41:52.395986", "stderr": "", "stdout": "blue"}

TASK: [blue test] *************************************************************
changed: [localhost] => {"changed": true, "cmd": ["echo", "blue"], "delta": "0:00:00.003406", "end": "2013-08-03 15:41:52.718623", "item": "", "rc": 0, "start": "2013-08-03 15:41:52.715217", "stderr": "", "stdout": "blue"}

PLAY RECAP ********************************************************************
localhost                  : ok=3    changed=2    unreachable=0    failed=0