I noticed regrtest claimed it cannot delete folder after test_tarfile
ran. It was like this.

Traceback (most recent call last):
  File "e:\python-dev\py3k\lib\runpy.py", line 160, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "e:\python-dev\py3k\lib\runpy.py", line 73, in _run_code
    exec(code, run_globals)
  File "e:\python-dev\py3k\lib\test\test_tarfile.py", line 1566, in <module>
    test_main()
  File "e:\python-dev\py3k\lib\test\test_tarfile.py", line 1563, in test_main
    shutil.rmtree(TEMPDIR)
  File "e:\python-dev\py3k\lib\shutil.py", line 283, in rmtree
    onerror(os.remove, fullname, sys.exc_info())
  File "e:\python-dev\py3k\lib\shutil.py", line 281, in rmtree
    os.remove(fullname)
WindowsError: [Error 32] プロセスはファイルにアクセスできません。別のプロセスが
使用中です。: 'E:\\PYTHON~1\\py3k\\@test_5276_tmp\\tmp.tar'

# It says "Process cannot access the file. Another process is using it."

I tried to reproduce this by running test_tarfile alone, but failed.
But I succeeded to do it with following command.
  py3k -m test.regrtest test_capi test_tarfile

(Probably there is timing problem like GC... The reason why I think
so is below)

I think _Stream object left opened after exception occured in (even
after returned from function Tarfile#open) because it lives in stack
frame. Because t._extfileobj is True by default, TarFile object won't close it explicitly.