Invalid check on the result of pthread_self() leads to libpython startup failure

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-10-30.17:29:23.016>
labels = ['interpreter-core', '3.7', 'type-crash']
title = 'Invalid check on the result of pthread_self() leads to libpython startup failure'
updated_at = <Date 2019-10-30.17:29:23.016>
user = 'https://bugs.python.org/tgl'

bugs.python.org fields:

activity = <Date 2019-10-30.17:29:23.016>
actor = 'tgl'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2019-10-30.17:29:23.016>
creator = 'tgl'
dependencies = []
files = []
hgrepos = []
issue_num = 38646
keywords = []
message_count = 1.0
messages = ['355723']
nosy_count = 1.0
nosy_names = ['tgl']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue38646'
versions = ['Python 3.7']