[subnet.cidr usage here](https://github.com/rackerlabs/quark/blob/master/quark/plugin_modules/subnets.py#L58)

on master branch: 
$ tox -e py26 -- quark.tests.plugin_modules.test_subnets:TestSubnetsNotification.test_create_subnet_notification

```
GLOB sdist-make: /home/vagrant/dev/quark/setup.py
py26 inst-nodeps: /home/vagrant/dev/quark/.tox/dist/quark-65b5ed1.zip
py26 runtests: commands[0] | nosetests quark.tests.plugin_modules.test_subnets:TestSubnetsNotification.test_create_subnet_notification
/home/vagrant/dev/quark/.tox/py26/lib/python2.6/site-packages/sqlalchemy/engine/strategies.py:117: SADeprecationWarning: The 'listeners' argument to Pool (and create_engine()) is deprecated.  Use event.listen().
  pool = poolclass(creator, **pool_args)
/home/vagrant/dev/quark/.tox/py26/lib/python2.6/site-packages/sqlalchemy/pool.py:160: SADeprecationWarning: Pool.add_listener is deprecated.  Use event.listen()
  self.add_listener(l)
E
======================================================================
ERROR: test_create_subnet_notification (quark.tests.plugin_modules.test_subnets.TestSubnetsNotification)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/vagrant/dev/quark/quark/tests/plugin_modules/test_subnets.py", line 809, in test_create_subnet_notification
    created_at=s["created_at"]))
  File "/usr/lib/python2.6/contextlib.py", line 34, in __exit__
    self.gen.throw(type, value, traceback)
  File "/home/vagrant/dev/quark/quark/tests/plugin_modules/test_subnets.py", line 795, in _stubs
    yield notify
  File "/home/vagrant/dev/quark/quark/tests/plugin_modules/test_subnets.py", line 801, in test_create_subnet_notification
    self.plugin.create_subnet(self.context, dict(subnet=s))
  File "/home/vagrant/dev/quark/quark/plugin.py", line 75, in _wrapped
    res = func(self, context, *args, **kwargs)
  File "/home/vagrant/dev/quark/quark/plugin.py", line 282, in create_subnet
    return subnets.create_subnet(context, subnet)
  File "/home/vagrant/dev/quark/quark/plugin_modules/subnets.py", line 95, in create_subnet
    _validate_subnet_cidr(context, net_id, sub_attrs["cidr"])
  File "/home/vagrant/dev/quark/quark/plugin_modules/subnets.py", line 58, in _validate_subnet_cidr
    if (netaddr.IPSet([subnet.cidr]) & new_subnet_ipset):
AttributeError: 'tuple' object has no attribute 'cidr'
-------------------- >> begin captured logging << --------------------
quark.drivers.base: INFO: load_config
quark.drivers.nvp_driver: INFO: Loading NVP settings None
quark.drivers.nvp_driver: INFO: Loading NVP settings []
quark.drivers.unmanaged: INFO: load_config
quark.plugin: INFO: Starting quark plugin
quark.plugin_modules.subnets: INFO: create_subnet for tenant fake
--------------------- >> end captured logging << ---------------------

----------------------------------------------------------------------
Ran 1 test in 0.117s

FAILED (errors=1)
ERROR: InvocationError: '/home/vagrant/dev/quark/.tox/py26/bin/nosetests quark.tests.plugin_modules.test_subnets:TestSubnetsNotification.test_create_subnet_notification'
__________________________________________________________________________________ summary __________________________________________________________________________________
ERROR:   py26: commands failed
```