pip editable modules incorrectly installed when setuptools>=60.0.0

[IgnacioHeredia]

Description

Hi all,

I found a bug in Ubuntu 20.04 related to pip and setuptools.

When you pip install a Python module in Ubuntu 20.04 in editable mode (-e flag), the module is not listed in pip.
When the module is installed normally (no -e flag), everything works as usual, and pip finds the module.

This happens because depending on the setuptools version, the module is installed at a different path (and thus not found in the PYTHONPATH in some cases):

• setuptools 45.2.0 works fine
  Module installation path: /usr/local/lib/python3.8/dist-packages/

$ python3 -c "import sys; print(sys.path)"
['', '/usr/lib/python38.zip', '/usr/lib/python3.8', '/usr/lib/python3.8/lib-dynload', '/usr/local/lib/python3.8/dist-packages', '/samplemod', '/usr/lib/python3/dist-packages']

• setuptools 62.4.0 breaks
  Module installation path: /usr/lib/python3.8/site-packages/

$ python3 -c "import sys; print(sys.path)"
['', '/usr/lib/python38.zip', '/usr/lib/python3.8', '/usr/lib/python3.8/lib-dynload', '/usr/local/lib/python3.8/dist-packages', '/usr/lib/python3/dist-packages']

The last working version is setuptools==59.8.0. Starting from setuptools==60.0.0 it breaks.

Expected behavior

The module should be correctly installed and listed.

$ pip3 list -e
Package Version Editable project location
------- ------- -------------------------
sample  0.1.0   /samplemod

pip version

22.1.2

Python version

3.8.10

OS

Ubuntu 20.04

How to Reproduce

I attach a minimal Dockerfile to reproduce the issue.

FROM ubuntu:20.04

# Refresh cache and install packages
RUN DEBIAN_FRONTEND=noninteractive apt-get update && \
    apt-get install -y --no-install-recommends git

# Install pip
RUN DEBIAN_FRONTEND=noninteractive apt-get install -y python3-pip
RUN pip install --upgrade setuptools  # THIS BREAKS THE INSTALLATION: setuptools 45.2.0 -->  setuptools 62.4.0
RUN pip install --upgrade pip  # pip 20.0.2 -->  pip 22.1.2

# Install sample Python module in **editable** (-e) mode
RUN git clone https://github.com/navdeep-G/samplemod && \
    cd  samplemod && \
    pip install -v -e . && \
    cd ..

# Check behaviour
RUN python3 --version
RUN pip --version
RUN pip list -e
RUN python3 -c "import sys; print(sys.path)"

Output

• setuptools 45.2.0 ✔️

Python 3.8.10
pip 22.1.2 from /usr/local/lib/python3.8/dist-packages/pip (python 3.8)

Pip install log:
[...] Creating /usr/local/lib/python3.8/dist-packages/sample.egg-link

$ pip3 list -e
Package Version Editable project location
------- ------- -------------------------
sample  0.1.0   /samplemod

• setuptools 62.4.0 ❌

Python 3.8.10
pip 22.1.2 from /usr/local/lib/python3.8/dist-packages/pip (python 3.8)

pip install logs:
[...] Creating /usr/lib/python3.8/site-packages/sample.egg-link (link to .)

$ pip3 list -e

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[uranusjr]

This should be reported to setuptools instead.