Untokenize and retokenize does not round-trip

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-12-02.11:06:14.288>
labels = ['type-bug', 'library', '3.10']
title = 'Untokenize and retokenize does not round-trip'
updated_at = <Date 2020-10-24.00:58:47.260>
user = 'https://github.com/Zac-HD'

bugs.python.org fields:

activity = <Date 2020-10-24.00:58:47.260>
actor = 'Zac Hatfield-Dodds'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2019-12-02.11:06:14.288>
creator = 'Zac Hatfield-Dodds'
dependencies = []
files = []
hgrepos = []
issue_num = 38953
keywords = []
message_count = 3.0
messages = ['357704', '379498', '379506']
nosy_count = 3.0
nosy_names = ['terry.reedy', 'meador.inge', 'Zac Hatfield-Dodds']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'test needed'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue38953'
versions = ['Python 3.10']