I created a CloudFormation stack using the template below via Boto3 Python method `cf_client.create_stack(StackName="test")`; however, when I attempt to call `s3_client.get_bucket_policy(Bucket="my-bucket")` I receive a `NoSuchBucketPolicy ... The bucket policy does not exist` error. 

```yaml
---
AWSTemplateFormatVersion: "2010-09-09"
Description: A sample template

Resources:
  TestBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: my-bucket
      AccessControl: PublicRead
      BucketEncryption:
        ServerSideEncryptionConfiguration:
          - ServerSideEncryptionByDefault:
              SSEAlgorithm: AES256

  TestBucketPolicy:
    Type: AWS::S3::BucketPolicy
    Properties:
      Bucket:
        Ref: TestBucket
      PolicyDocument:
        Id: TestBucketPolicy
        Statement:
          - Action:
              - "s3:GetObject"
            Effect: "Allow"
            Resource:
              Fn::Join:
                - ""
                - - "arn:aws:s3:::"
                  - Ref: TestBucket
                  - "/*"
            Principal: "*"
            Condition:
              StringLike:
                aws:Referer:
                  - "http://www.example.com/*"
                  - "http://example.com/*"
```

Is this something that's supported? 

Thanks in advance. 
return resolve_ref(stack_name, value['Ref'],
                resources, attribute='PhysicalResourceId')
        if keys_list and keys_list[0].lower() == 'fn::getatt':
            return resolve_ref(stack_name, value[keys_list[0]][0],
                resources, attribute=value[keys_list[0]][1])
        if keys_list and keys_list[0].lower() == 'fn::join':
            join_values = value[keys_list[0]][1]
            join_values = [resolve_refs_recursively(stack_name, v, resources) for v in join_values]
            none_values = [v for v in join_values if v is None]
            if none_values:
                raise Exception('Cannot resolve CF fn::Join %s due to null values: %s' % (value, join_values))
            return value[keys_list[0]][0].join(join_values)
        if keys_list and keys_list[0].lower() == 'fn::sub':
            item_to_sub = value[keys_list[0]]
            if not isinstance(item_to_sub, list):
                attr_refs = dict([(r, {'Ref': r}) for r in STATIC_REFS])
                item_to_sub = [item_to_sub, attr_refs]
            result = item_to_sub[0]
            for key, val in item_to_sub[1].items():
                val = resolve_refs_recursively(stack_name, val, resources)
                result = result.replace('${%s}' % key, val)
            return result
        else:
            for key, val in iteritems(value):
                value[key] = resolve_refs_recursively(stack_name, val, resources)
    if isinstance(value, list):
        for i in range(0, len(value)):
            value[i] = resolve_refs_recursively(stack_name, value[i], resources)
    return value
def get_stack_parameter(stack_name, parameter):