'Helper to build an os-unmanage req for the specified volume_id.'

def _get_resp(self, volume_id):

    req = webob.Request.blank(('/v2/%s/volumes/%s/action' % (self.ctxt.project_id, volume_id)))
    req.method = 'POST'
    req.headers['Content-Type'] = 'application/json'
    req.environ['cinder.context'] = self.ctxt
    body = {'os-unmanage': ''}
    req.body = jsonutils.dump_as_bytes(body)
    res = req.get_response(self.app)
    return res
