[issue44289] tarfile.is_tarfile() modifies file object's current position

Change by Roundup Robot : -- keywords: +patch nosy: +python-dev nosy_count: 1.0 -> 2.0 pull_requests: +25084 stage: -> patch review pull_request: https://github.com/python/cpython/pull/26488 ___ Python tracker

[issue44289] tarfile.is_tarfile() modifies file object's current position

New submission from Andrzej Mateja : Since Python 3.9 tarfile.is_tarfile accepts not only paths but also files and file-like objects (bpo-29435). Verification if a file or file-like object is a tar file modifies file object's current position. Imagine a function listing names of all tar