Implement os.putenv() with setenv() if available #83587

assignee = None
closed_at = <Date 2020-01-22.22:00:40.936>
created_at = <Date 2020-01-21.08:30:01.989>
labels = ['library', '3.9']
title = 'Implement os.putenv() with setenv() if available'
updated_at = <Date 2020-01-22.22:00:40.935>
user = 'https://github.com/vstinner'

activity = <Date 2020-01-22.22:00:40.935>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2020-01-22.22:00:40.936>
closer = 'vstinner'
components = ['Library (Lib)']
creation = <Date 2020-01-21.08:30:01.989>
creator = 'vstinner'
dependencies = []
files = []
hgrepos = []
issue_num = 39406
keywords = ['patch']
message_count = 15.0
messages = ['360365', '360370', '360371', '360378', '360386', '360388', '360419', '360421', '360422', '360424', '360445', '360505', '360509', '360511', '360513']
nosy_count = 3.0
nosy_names = ['vstinner', 'serhiy.storchaka', 'eryksun']
pr_nums = ['18095', '18106', '18126', '18128']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue39406'
versions = ['Python 3.9']