tarfile would fail to extract tarballs with files under R/O directories (twice)

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-05-23.03:49:43.778>
labels = ['expert-IO']
title = 'tarfile would fail to extract tarballs with files under R/O directories (twice)'
updated_at = <Date 2017-05-25.07:32:17.864>
user = 'https://bugs.python.org/YaroslavHalchenko'

bugs.python.org fields:

activity = <Date 2017-05-25.07:32:17.864>
actor = 'lars.gustaebel'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['IO']
creation = <Date 2017-05-23.03:49:43.778>
creator = 'Yaroslav.Halchenko'
dependencies = []
files = ['46888']
hgrepos = []
issue_num = 30438
keywords = ['patch']
message_count = 7.0
messages = ['294217', '294278', '294323', '294353', '294427', '294440', '294443']
nosy_count = 3.0
nosy_names = ['lars.gustaebel', 'Yaroslav.Halchenko', 'Catherine.Devlin']
pr_nums = ['1768', '1808']
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue30438'
versions = ['Python 2.7', 'Python 3.3', 'Python 3.4', 'Python 3.5', 'Python 3.6']