Revert "Merge branch 'improved-make-overridable' of git://github.com/ElvishJerricco/nixpkgs"

This reverts commit c3af1210b4, reversing
changes made to 49f175cd0c.

pkgs/development/haskell-modules/default.nix

@@ -7,8 +7,6 @@
 , configurationNix ? import ./configuration-nix.nix
 }:
 
-self: # Provided by `callPackageWithOutput`
-
 let
 
   inherit (lib) extends makeExtensible;
@@ -16,15 +14,19 @@ let
 
   haskellPackages = pkgs.callPackage makePackageSet {
     package-set = initialPackages;
-    extensible-self = self;
-    inherit stdenv haskellLib ghc;
+    inherit stdenv haskellLib ghc extensible-self;
   };
 
   commonConfiguration = configurationCommon { inherit pkgs haskellLib; };
   nixConfiguration = configurationNix { inherit pkgs haskellLib; };
 
-in (extends overrides
-     (extends packageSetConfig
-       (extends compilerConfig
-         (extends commonConfiguration
-           (extends nixConfiguration haskellPackages))))) self
+  extensible-self = makeExtensible
+    (extends overrides
+      (extends packageSetConfig
+        (extends compilerConfig
+          (extends commonConfiguration
+            (extends nixConfiguration haskellPackages)))));
+
+in
+
+  extensible-self