tarfile chokes on reading .tar file with no entries (but does fine if the same file is bzip2'ed)

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-03-08.19:32:09.906>
labels = ['3.7', 'type-bug', 'library']
title = "tarfile chokes on reading .tar file with no entries (but does fine if the same file is bzip2'ed)"
updated_at = <Date 2017-03-10.23:00:48.734>
user = 'https://github.com/posita'

bugs.python.org fields:

activity = <Date 2017-03-10.23:00:48.734>
actor = 'posita'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2017-03-08.19:32:09.906>
creator = 'posita'
dependencies = []
files = ['46712', '46719']
hgrepos = []
issue_num = 29760
keywords = ['patch']
message_count = 5.0
messages = ['289253', '289265', '289408', '289409', '289417']
nosy_count = 2.0
nosy_names = ['lars.gustaebel', 'posita']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue29760'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6', 'Python 3.7']