1e2b6695cf
When a PEP 517 project file is present, pip will not install prerequisites in `site-packages`: https://pip.pypa.io/en/stable/reference/pip/#pep-517-and-518-support For the shell hook, this has the consequence that the generated temporary directory that is added to PYTHONPATH does not contain `site.py`. As a result, Python does not discover the Python module. Thus when a user executes nix-shell in a project, they cannot import the project's Python module. This change adds the `--no-build-isolation` option to pip when creating the editable environment, to correctly generate `site.py`, even when a `pyproject.toml` is present.