email parser fails to decode quoted-printable rfc822 message attachemnt

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-08-31.18:04:32.922>
labels = ['expert-email', 'type-crash', '3.9']
title = 'email parser fails to decode quoted-printable rfc822 message attachemnt'
updated_at = <Date 2021-08-31.18:36:25.572>
user = 'https://github.com/anarcat'

bugs.python.org fields:

activity = <Date 2021-08-31.18:36:25.572>
actor = 'DiddiLeija'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['email']
creation = <Date 2021-08-31.18:04:32.922>
creator = 'anarcat'
dependencies = []
files = []
hgrepos = []
issue_num = 45066
keywords = []
message_count = 2.0
messages = ['400764', '400767']
nosy_count = 4.0
nosy_names = ['barry', 'r.david.murray', 'DiddiLeija', 'anarcat']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue45066'
versions = ['Python 3.9']