Description of problem:
Added a "tags" entry to a playbook where it wasn't expected, e.g.

- hosts:
  - myhosts
  tags: foo
  tasks:
  - name: do something
    debug: msg="foo"

Version-Release number of selected component:
ansible-1.1-0.git201303011750.fc18

Additional info:
cmdline:        /usr/bin/python /usr/bin/ansible-playbook -u root -i src/main/ansible/ansible_hosts_ci -vvvv src/main/ansible/deploy-ciserver.yml -t foo
executable:     /usr/bin/ansible-playbook
kernel:         3.8.3-203.fc18.x86_64
uid:            1000

Truncated backtrace:
__init__.py:192:path_dwim:AttributeError: 'dict' object has no attribute 'startswith'

Traceback (most recent call last):
  File "/usr/bin/ansible-playbook", line 205, in <module>
    sys.exit(main(sys.argv[1:]))
  File "/usr/bin/ansible-playbook", line 176, in main
    pb.run()
  File "/usr/lib/python2.7/site-packages/ansible/playbook/__init__.py", line 202, in run
    play = Play(self, play_ds, play_basedir)
  File "/usr/lib/python2.7/site-packages/ansible/playbook/play.py", line 81, in __init__
    self._update_vars_files_for_host(None)
  File "/usr/lib/python2.7/site-packages/ansible/playbook/play.py", line 316, in _update_vars_files_for_host
    filename4 = utils.path_dwim(self.basedir, filename3)
  File "/usr/lib/python2.7/site-packages/ansible/utils/__init__.py", line 192, in path_dwim
    if given.startswith("/"):
AttributeError: 'dict' object has no attribute 'startswith'

Local variables in innermost frame:
given: {'tags': 'foo'}
basedir: 'src/main/ansible'