pythonPackages.isort: fix build system, keep version for python 2

pkgs/development/python-modules/isort/4.nix

@@ -0,0 +1,43 @@
+{ lib, buildPythonPackage, fetchPypi, setuptools, isPy27, futures
+, backports_functools_lru_cache, mock, pytest
+}:
+
+let
+  skipTests = [ "test_requirements_finder" "test_pipfile_finder" ] ++ lib.optional isPy27 "test_standard_library_deprecates_user_issue_778";
+  testOpts = lib.concatMapStringsSep " " (t: "--deselect test_isort.py::${t}") skipTests;
+in buildPythonPackage rec {
+  pname = "isort";
+  version = "4.3.21"; # Note 4.x is the last version that supports Python2
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "54da7e92468955c4fceacd0c86bd0ec997b0e1ee80d97f67c35a78b719dccab1";
+  };
+
+  propagatedBuildInputs = [
+    setuptools
+  ] ++ lib.optionals isPy27 [ futures backports_functools_lru_cache ];
+
+  checkInputs = [ mock pytest ];
+
+  checkPhase = ''
+    # isort excludes paths that contain /build/, so test fixtures don't work
+    # with TMPDIR=/build/
+    PATH=$out/bin:$PATH TMPDIR=/tmp/ pytest ${testOpts}
+
+    # Confirm that the produced executable script is wrapped correctly and runs
+    # OK, by launching it in a subshell without PYTHONPATH
+    (
+      unset PYTHONPATH
+      echo "Testing that `isort --version-number` returns OK..."
+      $out/bin/isort --version-number
+    )
+  '';
+
+  meta = with lib; {
+    description = "A Python utility / library to sort Python imports";
+    homepage = "https://github.com/timothycrosley/isort";
+    license = licenses.mit;
+    maintainers = with maintainers; [ couchemar nand0p ];
+  };
+}

pkgs/development/python-modules/isort/default.nix

@@ -1,10 +1,9 @@
 { lib, buildPythonPackage, fetchFromGitHub
 , colorama
 , hypothesis
-, poetry
+, poetry-core
 , pylama
 , pytestCheckHook
-, setuptools
 }:
 
 let
@@ -20,10 +19,8 @@ in buildPythonPackage rec {
     sha256 = "1m7jpqssnbsn1ydrw1dn7nrcrggqcvj9v6mk5ampxmvk94xd2r2q";
   };
 
-  nativeBuildInputs = [ poetry ];
-
-  propagatedBuildInputs = [
-    setuptools
+  nativeBuildInputs = [
+    poetry-core
   ];
 
   checkInputs = [

pkgs/top-level/python-packages.nix

@@ -3056,8 +3056,10 @@ in {
 
   isodate = callPackage ../development/python-modules/isodate { };
 
-  isort = callPackage ../development/python-modules/isort {
-    inherit (pkgs) poetry;
+  isort = if isPy3k then
+    callPackage ../development/python-modules/isort { }
+  else
+    callPackage ../development/python-modules/isort/4.nix {
   };
 
   isoweek = callPackage ../development/python-modules/isoweek { };