venv isolation broken when debugging

[sil-lnagel]

Type: Bug

Behaviour

Expected vs. Actual

When I activate a virtual environment I expect python to use packages from this virtual environment over globally installed packages.

If run the debugger with the vscode python extension on Ubuntu sys.path contains /usr/lib/python3/dist-packages in front of the venv packages. This causes global packages to be loaded.

If you add export PYTHONPATH="" to .zshrc this is not added to sys.path during debug. But if you modify the PYTHONPATH eg to add a src folder inside your launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python Debugger: Current File with Arguments",
            "type": "debugpy",
            "request": "launch",
            "program": "${file}",
            "console": "integratedTerminal",
            "env": {
                "PYTHONPATH": "src"
            }
        }
    ]
}

it still shows up in sys.path

Steps to reproduce:

1. Create venv
2. Select venv in vscode
3. Create launch.json file as above
4. debug a python file and print sys.path
5. Verify that /usr/lib/python3/dist-packages is in path before venv folders

Diagnostic data

• Python version (& distribution if applicable, e.g. Anaconda): 3.9.18
• Type of virtual environment used (e.g. conda, venv, virtualenv, etc.): Venv
• Value of the python.languageServer setting: Default

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

XXX

User Settings

languageServer: "Pylance"

terminal
• activateEnvironment: false

Extension version: 2024.0.1
VS Code version: Code 1.86.2 (903b1e9d8990623e3d7da1df3d33db3e42d80eda, 2024-02-13T19:41:37.860Z)
OS version: Linux x64 6.2.0-39-generic
Modes:

A/B Experiments

vsliv368cf:30146710
vspor879:30202332
vspor708:30202333
vspor363:30204092
vscoreces:30445986
vscod805cf:30301675
binariesv615:30325510
vsaa593cf:30376535
py29gd2263:30899288
c4g48928:30535728
azure-dev_surveyone:30548225
vscrpc:30673769
962ge761:30959799
pythongtdpath:30769146
welcomedialog:30910333
pythonidxpt:30866567
pythonnoceb:30805159
asynctok:30898717
pythontestfixt:30902429
pythonregdiag2:30936856
pyreplss1:30897532
pythonmypyd1:30879173
pythoncet0:30885854
pythontbext0:30879054
dsvsc016:30899300
dsvsc017:30899301
dsvsc018:30899302
edj9j583:30958191
fegfb526:30961430
7j2b6412:30964151
ccp1r6:30958156

[irm-codebase]

I am having a similar issue with conda environments (#22918).
It seems like something is botched in the Python plugin.

[irm-codebase]

This is particularly annoying as I cannot debug properly unless I install the packages in the base environment.