pip fails to install pathlib in Ubuntu 22.04 with "setuptools is not available in the build environment"

[Rocko]

The latest 22.04 updates have broken pathlib. pip complains that setuptools is not available in the build environment even though the package python3-setuptools v59.6.0-1.2 is installed. This breaks any package relying on pathlib.

The output from the install command is:

rocko@ubuntu:~$ pip install pathlib
Defaulting to user installation because normal site-packages is not writeable
Collecting pathlib
  Downloading pathlib-1.0.1.tar.gz (49 kB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 49.3/49.3 KB 117.3 kB/s eta 0:00:00
  Preparing metadata (setup.py) ... error
  error: subprocess-exited-with-error

  × python setup.py egg_info did not run successfully.
  │ exit code: 1
  ╰─> [1 lines of output]
      ERROR: Can not execute `setup.py` since setuptools is not available in the build environment.
      [end of output]

  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

note: This is an issue with the package mentioned above, not pip.
hint: See above for details.

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: python3-pip 22.0.2+dfsg-1
ProcVersionSignature: Ubuntu 5.15.0-18.18-generic 5.15.12
Uname: Linux 5.15.0-18-generic x86_64
ApportVersion: 2.20.11-0ubuntu78
Architecture: amd64
CasperMD5CheckResult: pass
Date: Thu Mar 3 15:13:02 2022
InstallationDate: Installed on 2021-09-28 (156 days ago)
InstallationMedia: Ubuntu 21.10 "Impish Indri" - Beta amd64 (20210924)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
RebootRequiredPkgs: Error: path contained symlinks.
SourcePackage: python-pip
UpgradeStatus: Upgraded to jammy on 2022-02-18 (12 days ago)

[Rocko (rockorequin)]

Importing setuptools in a python interpreter works fine:

rocko@ubuntu:~$ python3
Python 3.10.2 (main, Feb 26 2022, 08:21:15) [GCC 11.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> try:
... import setuptools
... print('ok')
... except ImportError as error:
... print('failed')
...
ok
>>>

But this same code fails when pip tries to install pathlib:

rocko@ubuntu:~$ pip -v install pathlib
Using pip 22.0.2 from /usr/lib/python3/dist-packages/pip (python 3.10)
Defaulting to user installation because normal site-packages is not writeable
Collecting pathlib
  Using cached pathlib-1.0.1.tar.gz (49 kB)
  Running command python setup.py egg_info
  ERROR: Can not execute `setup.py` since setuptools is not available in the build environment.
  error: subprocess-exited-with-error

  × python setup.py egg_info did not run successfully.
  │ exit code: 1
  ╰─> See above for output.

  note: This error originates from a subprocess, and is likely not a problem with pip.
  full command: /usr/bin/python3 -c '
  exec(compile('"'"''"'"''"'"'
  # This is <pip-setuptools-caller> -- a caller that pip uses to run setup.py
  #
  # - It imports setuptools before invoking setup.py, to enable projects that directly
  # import from `distutils.core` to work with newer packaging standards.
  # - It provides a clear error message when setuptools is not installed.
  # - It sets `sys.argv[0]` to the underlying `setup.py`, when invoking `setup.py` so
  # setuptools doesn'"'"'t think the script is `-c`. This avoids the following warning:
  # manifest_maker: standard file '"'"'-c'"'"' not found".
  # - It generates a shim setup.py, for handling setup.cfg-only projects.
  import os, sys, tokenize

  try:
      import setuptools
  except ImportError as error:
      print(
          "ERROR: Can not execute `setup.py` since setuptools is not available in "
          "the build environment.",
          file=sys.stderr,
      )
      sys.exit(1)

  __file__ = %r

[Stefano Rivera (stefanor)]

> The latest 22.04 updates have broken pathlib.

If you're referring to a bug in the Debian-packaged python3-pathlib, unrelated to the pip issue described, then please expand on that. If there's a problem in pathlib we should get that fixed, ASAP. Currently there are no open bugs filed against pathlib: https://bugs.launchpad.net/ubuntu/+source/python-pathlib

I can confirm the pip bug, thanks. In Debian I can reproduce it with python 3.10, but not 3.9.

[Stefano Rivera (stefanor)]

And.... no, this is a bug in pathlib itself, not pip or python3.10 in debian:

root@warm-bird:/tmp/pathlib-1.0.1# python3
Python 3.10.2 (main, Feb 26 2022, 08:21:15) [GCC 11.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pathlib
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/tmp/pathlib-1.0.1/pathlib.py", line 10, in <module>
    from collections import Sequence
ImportError: cannot import name 'Sequence' from 'collections' (/usr/lib/python3.10/collections/__init__.py)

See the deprecation notice on:
https://pypi.org/project/pathlib/

The pathlib PyPI package hasn't been ported to Python 3.10. It masks the pathlib stdlib module, imported by setuptools, and so blows up pip.

Use pathlib2 instead.