Better error message on failing to create a venv due to failing ensurepip

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-10-29.10:00:06.597>
labels = []
title = 'Better error message on failing to create a venv due to failing ensurepip'
updated_at = <Date 2021-10-29.10:00:06.597>
user = 'https://github.com/JulienPalard'

bugs.python.org fields:

activity = <Date 2021-10-29.10:00:06.597>
actor = 'mdk'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = []
creation = <Date 2021-10-29.10:00:06.597>
creator = 'mdk'
dependencies = []
files = []
hgrepos = []
issue_num = 45667
keywords = []
message_count = 1.0
messages = ['405297']
nosy_count = 1.0
nosy_names = ['mdk']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue45667'
versions = []