bpo-34010: Fix tarfile read performance regression (GH-8020)


During buffered read, use a list followed by join instead of extending a bytes object.
This is how it was done before but changed in commit b506dc32c1a.
(cherry picked from commit 12a08c47601cadea8e7d3808502cdbcca87b2ce2)

Co-authored-by: hajoscher <hajoscher@gmail.com>
2 files changed