unittest use dir(module) to load test cases. Run unittest file by _PyRun_SimpleFileObject, have bug

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-03-26.07:44:05.883>
labels = []
title = 'unittest use dir(module) to load test cases. Run unittest file by _PyRun_SimpleFileObject, have bug'
updated_at = <Date 2021-03-26.07:44:05.883>
user = 'https://github.com/JunyiXie'

bugs.python.org fields:

activity = <Date 2021-03-26.07:44:05.883>
actor = 'JunyiXie'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = []
creation = <Date 2021-03-26.07:44:05.883>
creator = 'JunyiXie'
dependencies = []
files = []
hgrepos = []
issue_num = 43630
keywords = []
message_count = 1.0
messages = ['389540']
nosy_count = 1.0
nosy_names = ['JunyiXie']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue43630'
versions = []