Many regtest failures on Windows with non-ASCII account name

GitHub fields:

assignee = 'https://github.com/serhiy-storchaka'
closed_at = None
created_at = <Date 2021-09-12.09:50:10.188>
labels = ['type-bug', 'OS-windows', '3.10', '3.11', 'tests', 'expert-unicode', '3.9']
title = 'Many regtest failures on Windows with non-ASCII account name'
updated_at = <Date 2021-09-21.16:32:42.185>
user = 'https://bugs.python.org/minghua'

bugs.python.org fields:

activity = <Date 2021-09-21.16:32:42.185>
actor = 'steve.dower'
assignee = 'serhiy.storchaka'
closed = False
closed_date = None
closer = None
components = ['Tests', 'Unicode', 'Windows']
creation = <Date 2021-09-12.09:50:10.188>
creator = 'minghua'
dependencies = []
files = []
hgrepos = []
issue_num = 45176
keywords = []
message_count = 9.0
messages = ['401659', '401663', '401665', '401667', '402250', '402288', '402305', '402314', '402324']
nosy_count = 9.0
nosy_names = ['paul.moore', 'vstinner', 'tim.golden', 'ezio.melotti', 'zach.ware', 'serhiy.storchaka', 'eryksun', 'steve.dower', 'minghua']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue45176'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']