need to give valid error when allocation pool is outside of subnet

We need to give valid error when allocation pool is outside of subnet

root@nodec22:~# neutron subnet-create --name small_subnet --gateway 13.1.1.254 --allocation-pool start=14.1.1.0,end=14.1.1.10 vn1 13.1.1.0/24
Request Failed: internal server error while processing your request.
root@nodec22:~#

---------
server.log:

2014-06-13 21:19:14.206 ERROR [neutron.api.v2.resource] create failed
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/neutron/api/v2/resource.py", line 84, in resource
    result = method(request=request, **args)
  File "/usr/lib/python2.7/dist-packages/neutron/api/v2/base.py", line 405, in create
    obj = obj_creator(request.context, **kwargs)
  File "/usr/lib/python2.7/dist-packages/neutron_plugin_contrail/plugins/opencontrail/contrailplugin.py", line 361, in create_subnet
    raise e
HttpError: HTTP Status: 500 Content: subnet(default-domain:project1:vn1:13.1.1.0/24) allocation pool ({u'start': u'14.1.1.0', u'end': u'14.1.1.10'}) is out of cidr