shellcheck-py installation fails using pip 20.0.1

[fdegir]

When installing shellcheck-py, we started hitting installation errors.
Here is the details of the environment, python, pip, and shellcheck-py versions.

OS: Ubuntu1804
python: 3.5.3
pip version: 20.0.1
shellcheck-py: 0.7.0.1
requirements file: https://gerrit.nordix.org/gitweb?p=infra/engine.git;a=blob;f=test-requirements.txt

Here is the snippet that shows the problem.

pip install -r test-requirements.txt
Requirement already satisfied: pip==20.0.1 in ./.venv/lib/python3.5/site-packages (from -r test-requirements.txt (line 7)) (20.0.1)
Collecting tox==3.14.3
  Using cached tox-3.14.3-py2.py3-none-any.whl (80 kB)
Collecting ansible-lint==4.1.0
  Using cached ansible_lint-4.1.0-py2.py3-none-any.whl (54 kB)
Collecting yamllint==1.19.0
  Using cached yamllint-1.19.0-py2.py3-none-any.whl (57 kB)
Collecting shellcheck-py==0.7.0.1
  Using cached shellcheck_py-0.7.0.1.tar.gz (3.2 kB)
    ERROR: Command errored out with exit status 1:
     command: /home/jenkins/nordix/slave_root/engine/.venv/bin/python3 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-hu6_3hl8/shellcheck-py/setup.py'"'"'; __file__='"'"'/tmp/pip-install-hu6_3hl8/shellcheck-py/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-install-hu6_3hl8/shellcheck-py/pip-egg-info
         cwd: /tmp/pip-install-hu6_3hl8/shellcheck-py/
    Complete output (6 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-install-hu6_3hl8/shellcheck-py/setup.py", line 31
        return f'shellcheck-v{SHELLCHECK_VERSION}.{get_arch()}'
                                                              ^
    SyntaxError: invalid syntax
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

To reproduce the issue

virtualenv -p python3 .venv
source .venv/bin/activate
pip install shellcheck-py==0.7.0.1

This could be related to what's going on with pip as virtualenv pulls in pip 20.0.1 and things seem to be shaky. [0][1][2]
Installing shellcheck-py using an earlier pip version (19.0.3) works.

pip install pip==19.0.3 --force-reinstall
Collecting pip==19.0.3
  Using cached pip-19.0.3-py2.py3-none-any.whl (1.4 MB)
Installing collected packages: pip
  Attempting uninstall: pip
    Found existing installation: pip 20.0.1
    Uninstalling pip-20.0.1:
      Successfully uninstalled pip-20.0.1
Successfully installed pip-19.0.3
(.venv) jenkins@5810e48a14c2:~/nordix/slave_root/engine$ pip install shellcheck-py==0.7.0.1
Collecting shellcheck-py==0.7.0.1
  Using cached https://files.pythonhosted.org/packages/ea/d6/e3d1fc934774d5f2d2fd76484baa3bbb4f3172aa9eccff1a6d5bcc405c90/shellcheck_py-0.7.0.1-py2.py3-none-manylinux1_x86_64.whl
Installing collected packages: shellcheck-py
Successfully installed shellcheck-py-0.7.0.1
You are using pip version 19.0.3, however version 20.0.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

[0] pypa/pip#7621
[1] pypa/pip#7620
[2] pypa/pip#7624

[webknjaz]

@fdegir this is not related to the Pip issue. Your first log clearly shows that their setup.py script has f-strings which only work under Python 3.6+.

The second snippet shows that it uses a pre-cached wheel and doesn't download/select sdist from PyPI.

[fdegir]

thanks for the pointer @webknjaz. it works with python 3.6 as you said which I should have looked more carefully.

[webknjaz]

FWIW Pip seems to be also broken after all: pypa/pip#7626