old_contents: # vim: tabstop=4 shiftwidth=4 softtabstop=4
  
  #
  #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  from heat.common import exception
  from heat.engine import stack_resource
  from heat.common import template_format
  from heat.common import urlfetch
  
  from heat.openstack.common import log as logging
  
  logger = logging.getLogger(__name__)
  
  
  (PROP_TEMPLATE_URL,
   PROP_TIMEOUT_MINS,
   PROP_PARAMETERS) = ('TemplateURL', 'TimeoutInMinutes', 'Parameters')
  
  
  class NestedStack(stack_resource.StackResource):
      '''
      A Resource representing a child stack to allow composition of templates.
      '''
  
      properties_schema = {PROP_TEMPLATE_URL: {'Type': 'String',
                                               'Required': True},
                           PROP_TIMEOUT_MINS: {'Type': 'Number'},
                           PROP_PARAMETERS: {'Type': 'Map'}}
  
      def handle_create(self):
          template_data = urlfetch.get(self.properties[PROP_TEMPLATE_URL])
          template = template_format.parse(template_data)
  
          self.create_with_template(template, self.properties[PROP_PARAMETERS])
          self.resource_id_set(self.nested().identifier().arn())
  
      def handle_update(self, json_snippet):
          return self.UPDATE_REPLACE
  
      def handle_delete(self):
          self.delete_nested()
  
      def FnGetAtt(self, key):
          if not key.startswith('Outputs.'):
              raise exception.InvalidTemplateAttribute(
                  resource=self.physical_resource_name(), key=key)
  
          prefix, dot, op = key.partition('.')
          return unicode(self.get_output(op))
  
  
  def resource_mapping():
      return {
          'AWS::CloudFormation::Stack': NestedStack,
      }
  
new_contents: # vim: tabstop=4 shiftwidth=4 softtabstop=4
  
  #
  #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  from heat.common import exception
  from heat.engine import stack_resource
  from heat.common import template_format
  from heat.common import urlfetch
  
  from heat.openstack.common import log as logging
  
  logger = logging.getLogger(__name__)
  
  
  (PROP_TEMPLATE_URL,
   PROP_TIMEOUT_MINS,
   PROP_PARAMETERS) = ('TemplateURL', 'TimeoutInMinutes', 'Parameters')
  
  
  class NestedStack(stack_resource.StackResource):
      '''
      A Resource representing a child stack to allow composition of templates.
      '''
  
      properties_schema = {PROP_TEMPLATE_URL: {'Type': 'String',
                                               'Required': True},
                           PROP_TIMEOUT_MINS: {'Type': 'Number'},
                           PROP_PARAMETERS: {'Type': 'Map'}}
  
      def handle_create(self):
          template_data = urlfetch.get(self.properties[PROP_TEMPLATE_URL])
          template = template_format.parse(template_data)
  
          self.create_with_template(template, self.properties[PROP_PARAMETERS])
  
      def handle_update(self, json_snippet):
          return self.UPDATE_REPLACE
  
      def handle_delete(self):
          self.delete_nested()
  
      def FnGetRefId(self):
          return self.nested().identifier().arn()
  
      def FnGetAtt(self, key):
          if not key.startswith('Outputs.'):
              raise exception.InvalidTemplateAttribute(
                  resource=self.physical_resource_name(), key=key)
  
          prefix, dot, op = key.partition('.')
          return unicode(self.get_output(op))
  
  
  def resource_mapping():
      return {
          'AWS::CloudFormation::Stack': NestedStack,
      }
  
subject: Revert NestedStack FnGetRefId changes