Package: python3-pip Version: 20.3.4-4 Severity: normal Dear maintainers,
consider the following minimal Python project with setuptools packaging and a "pyproject.toml" file (see PEP 518 and [1]): > tree myproject myproject |-- myproject | `-- __init__.py |-- pyproject.toml |-- setup.cfg `-- setup.py Performing an editable system-wide install of this (i.e. running `pip install -e` outside a venv) results in a successful pip invocation, but a non-importable module: > python3 >>> import myproject Traceback (most recent call last): File "<stdin>", line 1, in <module> ModuleNotFoundError: No module named 'myproject' Everything works fine when a venv *or* a non-editable install is used instead. The reason for this is that the target files end up in "/usr/lib/python3.9/site-packages", which is not part of the default Debian Python module paths [2]: > ls /usr/lib/python3.9/site-packages easy-install.pth myproject.egg-link Having a PEP 518 package enables pip build isolation by default, which appears to cause the issue. One can work around it by using `pip install --no-build-isolation -e`. In that case, the target files are created in "/usr/local/lib/python3.9/dist-packages" instead. Best, Felix [1] https://setuptools.pypa.io/en/latest/build_meta.html [2] https://salsa.debian.org/cpython-team/python3-defaults/-/blob/master/policy/interpreter.rst
