[New-bugs-announce] [issue41925] Lowercase path to python.exe in pip.exe from venv is throwing error

[Chris Tse]

New submission from Chris Tse <christse at hey.com>:

Following up on https://bugs.python.org/issue37369 as it was advised to open a new issue regarding case sensitivity.

I am on Windows 10 running Version 10.0.19041 Build 19041. I am experiencing the same problem in that issue when using venv on Powershell. 
The path to python.exe in the pip.exe generated by venv is all lowercase, which is the source of this error.
After activating the venv with Activate.ps1 and attempting to use pip, I get the following error, while activate.bat on cmd works fine:

Fatal error in launcher: Unable to create process using '"c:\users\chris\code\project\myenv\scripts\python.exe"  "C:\Users\chris\code\project\myenv\Scripts\pip.exe" ': The system cannot find the file specified.


Full steps to reproduce:
  1. Install Python 3.8.6 from python.org (ticking add to PATH option in installer)
  2. Open Powershell (via both native Powershell app or the new Windows Terminal) and verify that `python` is bound to the correct Version
  3. Run `python -m venv myenv`
  4. Run `.\myenv\Scripts\Activate.ps1`
  5. Run `pip`

Expected behavior: Get the pip usage commands list

Actual behavior: Get the above Fatal error

Notes:
I did not explicitly set case sensitivity on my machine. All my drives are formatted as NTFS, but should not be case sensitive, which can be confirmed by fsutils:

> fsutil.exe file queryCaseSensitiveInfo C:\
Case sensitive attribute on directory C:\ is disabled.

Attempting to actually call that python.exe using the full lowercase path throws a similar error. 

Someone I know who has been helping with debugging this ran the Scripts\activate script successfully on the same version of Powershell as mine (5.1.19041.1) which should be meant for use on bash. I however was not able to do so.

----------
components: Windows
messages: 377916
nosy: chris-tse, paul.moore, steve.dower, tim.golden, zach.ware
priority: normal
severity: normal
status: open
title: Lowercase path to python.exe in pip.exe from venv is throwing error
versions: Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue41925>
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