The following list of tests make assumptions about custom RGW headers in the S3 responses :

1. s3tests_boto3.functional.test_s3.test_abort_multipart_upload
2. s3tests_boto3.functional.test_s3.test_bucket_head_extended
3. s3tests_boto3.functional.test_s3.test_encryption_sse_c_multipart_upload
4. s3tests_boto3.functional.test_s3.test_multipart_upload
5. s3tests_boto3.functional.test_s3.test_sse_kms_multipart_upload

The tests expect a response that contain custom headers like x-rgw-bytes-used and x-rgw-object-count, etc. which are not a part of the Amazon AWS S3 spec.