[Python-modules-team] Bug#955414: python3-pip: pip fails to install packages with pyproject.toml

[Christoph Reiter]

Package: python3-pip
Version: 20.0.2-2
Severity: important

Dear Maintainer,

(Note: This doesn't affect upstream pip, only the Debian/Ubuntu version)

pip in Debian (and Ubuntu focal) fails to install Python packages which contain
a pyproject.toml
file. I've initially reported this upstream, but it turns out this is only
broken in the Debian version of pip.

Related upstream issues:

* https://github.com/pypa/pip/issues/7946
* https://github.com/pypa/pip/issues/7874

I've created a minimal reproducer:

https://github.com/lazka/pip-pyproject-bug

pip installing this "package" results in:

Processing /home/lazka/Desktop/dsfsf/pip-pyproject-bug/pip-pyproject-bug
  Installing build dependencies ... done
  Getting requirements to build wheel ... error
  ERROR: Command errored out with exit status 1:
   command: /home/lazka/Desktop/dsfsf/pip-pyproject-bug/pip-pyproject-
bug/_venv/bin/python3 /home/lazka/Desktop/dsfsf/pip-pyproject-bug/pip-
pyproject-bug/_venv/share/python-wheels/pep517-0.7.0-py2.py3-none-
any.whl/pep517/_in_process.py get_requires_for_build_wheel /tmp/tmpjl9p5766
       cwd: /tmp/pip-req-build-k6iv_ei5
  Complete output (1 lines):
  /home/lazka/Desktop/dsfsf/pip-pyproject-bug/pip-pyproject-
bug/_venv/bin/python3: can't find '__main__' module in
'/home/lazka/Desktop/dsfsf/pip-pyproject-bug/pip-pyproject-
bug/_venv/share/python-wheels/pep517-0.7.0-py2.py3-none-
any.whl/pep517/_in_process.py'
  ----------------------------------------
ERROR: Command errored out with exit status 1: /home/lazka/Desktop/dsfsf/pip-
pyproject-bug/pip-pyproject-bug/_venv/bin/python3
/home/lazka/Desktop/dsfsf/pip-pyproject-bug/pip-pyproject-
bug/_venv/share/python-wheels/pep517-0.7.0-py2.py3-none-
any.whl/pep517/_in_process.py get_requires_for_build_wheel /tmp/tmpjl9p5766
Check the logs for full command output.



-- System Information:
Debian Release: bullseye/sid
  APT prefers unstable
  APT policy: (900, 'unstable'), (900, 'testing'), (500, 'unstable-debug'), (500, 'testing-debug')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.4.0-4-amd64 (SMP w/4 CPU cores)
Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8), LANGUAGE=en_US.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages python3-pip depends on:
ii  ca-certificates    20190110
ii  python-pip-whl     20.0.2-2
ii  python3            3.8.2-2
ii  python3-distutils  3.8.2-2
ii  python3.7          3.7.7-1

Versions of packages python3-pip recommends:
ii  build-essential     12.8
ii  python3-dev         3.8.2-2
ii  python3-setuptools  44.0.0-1
ii  python3-wheel       0.34.2-1

python3-pip suggests no packages.

-- no debconf information