[issue45148] ensurepip upgrade fails

[baterflyrity]

New submission from baterflyrity <baterflyrity at yandex.ru>:

Upgrading pip via ensurepip unfortunately doesn't do anything wealthy.

```bash
user at host MINGW64 ~
$ pip list | grep pip
pip                       21.2.3
WARNING: You are using pip version 21.2.3; however, version 21.2.4 is available.
You should consider upgrading via the 'C:\Python39\python.exe -m pip install --upgrade pip' command.

user at host MINGW64 ~
$ py -m ensurepip --upgrade
Looking in links: c:\Users\BATERF~1\AppData\Local\Temp\tmpuv4go5fy
Requirement already satisfied: setuptools in c:\python39\lib\site-packages (57.4.0)
Requirement already satisfied: pip in c:\python39\lib\site-packages (21.2.3)

user at host MINGW64 ~
$ pip list | grep pip
pip                       21.2.3
WARNING: You are using pip version 21.2.3; however, version 21.2.4 is available.
You should consider upgrading via the 'C:\Python39\python.exe -m pip install --upgrade pip' command.
```

----------
components: Windows
messages: 401436
nosy: baterflyrity, paul.moore, steve.dower, tim.golden, zach.ware
priority: normal
severity: normal
status: open
title: ensurepip upgrade fails
versions: Python 3.9

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue45148>
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