Race condition in shutil.copyfile(): source file replaced file during copy

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-05-18.20:22:00.056>
labels = ['type-security', '3.8', 'library']
title = 'Race condition in shutil.copyfile(): source file replaced file during copy'
updated_at = <Date 2018-08-14.05:17:08.289>
user = 'https://github.com/pkmoore'

bugs.python.org fields:

activity = <Date 2018-08-14.05:17:08.289>
actor = 'Preston Moore'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2017-05-18.20:22:00.056>
creator = 'Preston Moore'
dependencies = []
files = []
hgrepos = []
issue_num = 30400
keywords = []
message_count = 12.0
messages = ['293938', '293940', '296037', '321069', '321201', '321278', '321468', '321640', '321649', '321696', '322235', '323501']
nosy_count = 4.0
nosy_names = ['vstinner', 'giampaolo.rodola', 'zach.ware', 'Preston Moore']
pr_nums = ['1659']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'security'
url = 'https://bugs.python.org/issue30400'
versions = ['Python 3.8']