Pixi 0.8 doesn't work with editable installations

[Hofer-Julian]

Checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pixi, using pixi --version.

Reproducible example

When using pixi, I typically add an editable installation of my current Python package.
This looks something like this:

[project]
name = "pixi-0.8"
version = "0.1.0"

channels = ["conda-forge"]
platforms = ["win-64", "linux-64", "osx-arm64", "osx-64"]

[tasks]
install = "pip install --editable python"
import = "python -c 'import test_package'"

[dependencies]
python = "3.12.0.*"
pip = "23.3.1.*"

Starting from pixi 0.8, running pixi run install and then pixi run import gives this:

✨ Pixi task: python -c 'import test_package'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ModuleNotFoundError: No module named 'test_package'

You can find the complete example here: https://github.com/Hofer-Julian/pixi-0.8

According to our CI, it should happen on Windows, macOS and Linux.

Issue description

While pixi didn't support installation via pip, it was possible to install packages with pixi tasks.
Editable installations are broken since 0.8.
It seems like "normal", non-editable installations still work as expected.

Expected behavior

Ideally editable install would be directly supported by pixi. Alternatively, it would be great if one can at least install packages via pixi tasks.

[ruben-arts]

Thanks for the example and letting us know, we're on it!

[ruben-arts]

We think the issue is that we "uninstall" every package that our lock file doesn't specify as needed. This might be an easy fix. @baszalmstra is on it!

[Hofer-Julian]

Wow, that was fast. Thanks for taking care of this @baszalmstra!