configured libdir not correctly passed to Python executable

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-04-30.11:15:47.996>
labels = ['3.8', 'build', 'expert-installation']
title = 'configured libdir not correctly passed to Python executable'
updated_at = <Date 2019-12-10.07:51:18.677>
user = 'https://github.com/michael-o'

bugs.python.org fields:

activity = <Date 2019-12-10.07:51:18.677>
actor = 'xdegaye'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Build', 'Installation']
creation = <Date 2019-04-30.11:15:47.996>
creator = 'michael-o'
dependencies = []
files = []
hgrepos = []
issue_num = 36758
keywords = []
message_count = 2.0
messages = ['341148', '341354']
nosy_count = 3.0
nosy_names = ['vstinner', 'michael-o', 'Jeffrey.Kintscher']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue36758'
versions = ['Python 3.8']