input() with malformed input stream triggers assertion failure

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-05-15.22:17:06.863>
labels = ['interpreter-core', '3.8', '3.7', 'library', '3.9']
title = 'input() with malformed input stream triggers assertion failure'
updated_at = <Date 2020-05-15.22:18:33.456>
user = 'https://github.com/tekknolagi'

bugs.python.org fields:

activity = <Date 2020-05-15.22:18:33.456>
actor = 'tekknolagi'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Interpreter Core', 'Library (Lib)']
creation = <Date 2020-05-15.22:17:06.863>
creator = 'tekknolagi'
dependencies = []
files = []
hgrepos = []
issue_num = 40638
keywords = ['patch']
message_count = 1.0
messages = ['368982']
nosy_count = 1.0
nosy_names = ['tekknolagi']
pr_nums = ['20125']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue40638'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8', 'Python 3.9']