Create_Attachment doesn't seem to work

The python create_attachment call in the git client doesn't seem to work correctly. If you use it as currently implemented you get a 'azure.devops.exceptions.AzureDevOpsServiceError: Nullable object must have a value' exception.

I saw the example as part of issue 129: https://github.com/microsoft/azure-devops-python-api/issues/129 but that throws the same exception.

If I instead change the create_attachment call to:

def create_attachment(self, upload_stream, file_name, repository_id, pull_request_id, project=None, **kwargs):
        """CreateAttachment.
        [Preview API] Attach a new file to a pull request.
        :param object upload_stream: Stream to upload
        :param str file_name: The name of the file.
        :param str repository_id: The repository ID of the pull request’s target branch.
        :param int pull_request_id: ID of the pull request.
        :param str project: Project ID or project name
        :rtype: :class:`<Attachment> <azure.devops.v6_0.git.models.Attachment>`
        """
        route_values = {}
        if project is not None:
            route_values['project'] = self._serialize.url('project', project, 'str')
        if file_name is not None:
            route_values['fileName'] = self._serialize.url('file_name', file_name, 'str')
        if repository_id is not None:
            route_values['repositoryId'] = self._serialize.url('repository_id', repository_id, 'str')
        if pull_request_id is not None:
            route_values['pullRequestId'] = self._serialize.url('pull_request_id', pull_request_id, 'int')
        if "callback" in kwargs:
            callback = kwargs["callback"]
        else:
            callback = None
        # content = self._client.stream_upload(upload_stream, callback=callback)
        response = self._send(http_method='POST',
                              location_id='965d9361-878b-413b-a494-45d5b5fd8ab7',
                              version='6.0-preview.1',
                              route_values=route_values,
                              content=upload_stream.read(),
                              media_type='application/octet-stream')
        return self._deserialize('Attachment', response)

things work.

Bắt đầu từ phần triển khai create_attachment của ứng dụng khách Git bằng Python và so sánh với giải pháp thay thế được nêu trong issue này cũng như ví dụ từ issue 129. Tái hiện ngoại lệ Nullable object must have a value, sau đó xác minh rằng hành vi đã được sửa tạo thành công tệp đính kèm cho pull request.