functools.singledispatch doesn't verify annotation is on FIRST parameter

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-05-01.07:04:01.217>
labels = ['type-bug', 'library', '3.9', '3.10', '3.11']
title = "functools.singledispatch doesn't verify annotation is on FIRST parameter"
updated_at = <Date 2021-11-09.22:47:09.886>
user = 'https://github.com/Dutcho'

bugs.python.org fields:

activity = <Date 2021-11-09.22:47:09.886>
actor = 'AlexWaygood'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2020-05-01.07:04:01.217>
creator = 'Dutcho'
dependencies = []
files = []
hgrepos = []
issue_num = 40464
keywords = ['patch']
message_count = 4.0
messages = ['367824', '368079', '368095', '406062']
nosy_count = 6.0
nosy_names = ['rhettinger', 'lukasz.langa', 'Dutcho', 'FFY00', 'bim_bam', 'AlexWaygood']
pr_nums = ['19871']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue40464'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']