Error while building fastprogress

[maggesi]

Hello,

thank you for this amazing material!

I get the following error:

$ nix-shell
these derivations will be built:
  /nix/store/gd7b23dir54khmvp6834ych3lgxcxybz-python3.7-fastprogress-0.1.20.drv
 [...]
building '/nix/store/gd7b23dir54khmvp6834ych3lgxcxybz-python3.7-fastprogress-0.1.20.drv'...
unpacking sources
unpacking source archive /nix/store/9i31y8dm06rcn2m5s2lyxmswh3clwzyg-fastprogress-0.1.20.tar.gz
source root is fastprogress-0.1.20
setting SOURCE_DATE_EPOCH to timestamp 1550766561 of file fastprogress-0.1.20/setup.cfg
patching sources
configuring
building
Download error on https://pypi.org/simple/pytest-runner/: [Errno -2] Name or service not known -- Some packages may not be found!
Couldn't find index page for 'pytest-runner' (maybe misspelled?)
Download error on https://pypi.org/simple/: [Errno -2] Name or service not known -- Some packages may not be found!
No local packages or working download links found for pytest-runner
Traceback (most recent call last):
  File "nix_run_setup", line 8, in <module>
    exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\\r\\n', '\\n'), __file__, 'exec'))
  File "setup.py", line 25, in <module>
    test_suite = 'tests',
  File "/nix/store/nqvqkrkfbl824bsv5zfyjj55h1rvyvbq-python3.7-bootstrapped-pip-18.1/lib/python3.7/site-packages/setuptools/__init__.py", line 142, in setup
    _install_setup_requires(attrs)
  File "/nix/store/nqvqkrkfbl824bsv5zfyjj55h1rvyvbq-python3.7-bootstrapped-pip-18.1/lib/python3.7/site-packages/setuptools/__init__.py", line 137, in _install_setup_requires
    dist.fetch_build_eggs(dist.setup_requires)
  File "/nix/store/nqvqkrkfbl824bsv5zfyjj55h1rvyvbq-python3.7-bootstrapped-pip-18.1/lib/python3.7/site-packages/setuptools/dist.py", line 586, in fetch_build_eggs
    replace_conflicting=True,
  File "/nix/store/nqvqkrkfbl824bsv5zfyjj55h1rvyvbq-python3.7-bootstrapped-pip-18.1/lib/python3.7/site-packages/pkg_resources/__init__.py", line 780, in resolve
    replace_conflicting=replace_conflicting
  File "/nix/store/nqvqkrkfbl824bsv5zfyjj55h1rvyvbq-python3.7-bootstrapped-pip-18.1/lib/python3.7/site-packages/pkg_resources/__init__.py", line 1063, in best_match
    return self.obtain(req, installer)
  File "/nix/store/nqvqkrkfbl824bsv5zfyjj55h1rvyvbq-python3.7-bootstrapped-pip-18.1/lib/python3.7/site-packages/pkg_resources/__init__.py", line 1075, in obtain
    return installer(requirement)
  File "/nix/store/nqvqkrkfbl824bsv5zfyjj55h1rvyvbq-python3.7-bootstrapped-pip-18.1/lib/python3.7/site-packages/setuptools/dist.py", line 653, in fetch_build_egg
    return cmd.easy_install(req)
  File "/nix/store/nqvqkrkfbl824bsv5zfyjj55h1rvyvbq-python3.7-bootstrapped-pip-18.1/lib/python3.7/site-packages/setuptools/command/easy_install.py", line 673, in easy_install
    raise DistutilsError(msg)
distutils.errors.DistutilsError: Could not find suitable distribution for Requirement.parse('pytest-runner')
builder for '/nix/store/gd7b23dir54khmvp6834ych3lgxcxybz-python3.7-fastprogress-0.1.20.drv' failed with exit code 1