Troubles with propagated build inputs

default.nix

{ pkgs ?
  import (fetchTarball "http://nixos.org/channels/nixos-20.09/nixexprs.tar.xz")
  { } }:

pkgs.python3Packages.buildPythonApplication {
  pname = "load";
  src = ./.;
  version = "0.3.0";
  propagatedBuildInputs = with pkgs.python38Packages; [
    python-dotenv
    joblib
    multiprocess
  ];
}

load.py

#!/usr/bin/env python
import multiprocessing
from optparse import OptionParser
from pathlib import Path
from dotenv import dotenv_values
from joblib import Parallel

num_cores = multiprocessing.cpu_count()
parser = OptionParser(
    usage="%prog [options] file...\n\nLoad CSV files into a sql database",
    version="%prog v0.3.0",
)
parser.add_option(
    "-d",
    "--drop-schema",
    dest="drop_schema",
    action="store_true",
    help="Drop existing database schema before create",
)
parser.add_option(
    "-f",
    "--environment-file",
    dest="environment_file",
    help="Location of environment file containing credentials",
    default=Path(".") / ".env",
)
parser.add_option(
    "-s",
    "--db-schema",
    dest="db_schema",
    type="string",
    help="The database schema to load .csv files into",
)
parser.add_option(
    "-t",
    "--type",
    dest="db_type",
    type="string",
    default="postgresql",
    help="Type of sql database (postgresql or athena)",
)
(options, args) = parser.parse_args()


def print_arg(arg):
    print(f"arg: {arg}")


def run():
    Parallel(n_jobs=num_cores)(delayed(print_arg)(i) for i in args)


if __name__ == "__main__":
    run()

setup.py

from setuptools import setup

setup(
    name="load",
    version="0.3.0",
    py_modules=["load"],
    entry_points={"console_scripts": ["load = load:run"]},
)

Hey @djanatyn did you have a chance to take a look at this build issue with python? Any tips would be greatly appreciated. Thanks.