python3 shebang does not work with py.exe and venv on Windows

[oldium]

Bug report

Have the following:

1. py.exe set-up to start Python programs (with PATHEXT env var set to ...;.PY)
2. venv environment with Python 3

Now running Python program with shebang #! /usr/bin/env python works fine, but #! /usr/bin/env python3 does not.

I am running the same script on Debian 11:

1. Debian 11 has only python3 and python3.9 executables system-wide, so python shebang does not work, but python3 works.
2. Debian 11 venv environment (used during development) has python, python3 and python3.9 executables, so both python and python3 shebangs work.
3. Windows 11 has only python.exe under venv, so python3 shebang picks-up MS Store version and not the venv version, so it has wrong modules.

On Debian 11 the only usable shebang for all my use cases is python3, but that one does not work under Windows.

Current workaround is to make a copy on Windows in venv/Scripts/python.exe to venv/Scripts/python3.exe. Then the python3 shebang works fine.

Your environment

• Debian 11 with Python 3.9
• Windows 11 22H2
  • py.exe left by installation of previous Python MSI version after uninstalling Python (and intentionally keeping py.exe).
  • Python 3.11 installed via MS Store

[arhadthedev]

This issue was raised before, however there is no clear resolution:

• Windows python3 executable #99185
• Script containing a "shebang" would not start under Windows  #100107
• [Windows] installations should include pythonX.exe and pythonX.Y.exe executables #65705
• Windows py.exe launcher interacts badly with Windows store python.exe shim #84864

cc @zooba @FFY00 @eryksun

[arhadthedev]

Also related:

• Python3 installer is broken on Windows #99923
• Python launcher on Windows does not detect active venv #83180

[oldium]

😢

[eryksun]

At least the new py launcher that's included with Python 3.11 supports searching PATH for "python3.exe" when handling the shebang "#!/usr/bin/env python3". It's just a matter of making "python3.exe" available in virtual environments, which can be implemented by a symlink, hardlink, or copy.

The launcher could also implement "#!/usr/bin/env python[3]" to prefer an active virtual environment over searching PATH. That diverges from the behavior of "/usr/bin/env" on POSIX, but on the plus side it's retroactive for previous versions instead of depending on new venv behavior in Python 3.12+.

[zooba]

I believe this was fixed as #83180/#108101. Feel free to reopen if those didn't address this issue.

[oldium]

Thanks, I will test this with 3.13 release, then.