urllib.parse.urlsplit parses schemes that do not begin with letters

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-04-27.19:59:49.361>
labels = ['3.7', '3.8', 'type-bug', 'library', '3.9']
title = 'urllib.parse.urlsplit parses schemes that do not begin with letters'
updated_at = <Date 2020-04-27.20:21:34.776>
user = 'https://github.com/sgg'

bugs.python.org fields:

activity = <Date 2020-04-27.20:21:34.776>
actor = 'sgg'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2020-04-27.19:59:49.361>
creator = 'sgg'
dependencies = []
files = []
hgrepos = []
issue_num = 40409
keywords = ['patch']
message_count = 1.0
messages = ['367452']
nosy_count = 1.0
nosy_names = ['sgg']
pr_nums = ['19741']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue40409'
versions = ['Python 3.5', 'Python 3.6', 'Python 3.7', 'Python 3.8', 'Python 3.9']