Revert "buildSetupcfg: Include unzip for zip sources."

Misunderstood the error I was seeing.

This reverts commit 0d3eb70133.

pkgs/build-support/build-setupcfg/default.nix

@@ -6,7 +6,7 @@
 # * application: Whether this package is a python library or an
 #   application which happens to be written in python.
 # * doCheck: Whether to run the test suites.
-{ pkgs, pythonPackages }:
+pythonPackages:
 { src, info, meta ? {}, application ? false, doCheck ? true }: let
   build = if application
     then pythonPackages.buildPythonApplication
@@ -16,9 +16,7 @@ in build {
 
   inherit src meta doCheck;
 
-  nativeBuildInputs = [
-    pkgs.unzip
-  ] ++ map (p: pythonPackages.${p}) (
+  nativeBuildInputs = map (p: pythonPackages.${p}) (
     (info.setup_requires or []) ++
     (if doCheck then (info.tests_require or []) else []));
 

pkgs/top-level/python-packages.nix

@@ -67,8 +67,7 @@ let
   }));
 
   # See build-setupcfg/default.nix for documentation.
-  buildSetupcfg = import ../build-support/build-setupcfg
-    { inherit pkgs; pythonPackages = self; };
+  buildSetupcfg = import ../build-support/build-setupcfg self;
 
   graphiteVersion = "1.0.2";