insomniacslk added the comment:
The documentation should be updated to suggest that a custom file-like object
can be passed to have custom compressors then.
However this sounds very hacky and definitely not a feature that can be easily
passed to the user. Hence the reason for a cleaner
New submission from insomniacslk:
Tarfile would benefit from exposing custom compressors. At the moment the only
way to use something that is not gzip/bzip/lzma is to separate the archiving
and compression steps.
A possible approach is to pass a custom compression function
