Cmd.complete does not handle cmd=None

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2018-11-17.23:06:01.739>
labels = ['3.8', 'type-bug', 'library']
title = 'Cmd.complete does not handle cmd=None'
updated_at = <Date 2021-09-07.14:24:40.604>
user = 'https://github.com/blueyed'

bugs.python.org fields:

activity = <Date 2021-09-07.14:24:40.604>
actor = 'iritkatriel'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2018-11-17.23:06:01.739>
creator = 'blueyed'
dependencies = []
files = []
hgrepos = []
issue_num = 35270
keywords = ['patch']
message_count = 2.0
messages = ['330035', '401285']
nosy_count = 2.0
nosy_names = ['blueyed', 'iritkatriel']
pr_nums = ['10588']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue35270'
versions = ['Python 3.8']