lib.newScope: allow overriding callPackage

lib/customisation.nix

@@ -631,9 +631,12 @@ rec {
   makeScope =
     newScope: f:
     let
-      self = f self // {
-        newScope = scope: newScope (self // scope);
+      self = {
         callPackage = self.newScope { };
+      }
+      // f self
+      // {
+        newScope = scope: newScope (self // scope);
         overrideScope = g: makeScope newScope (extends g f);
         packages = f;
       };

pkgs/top-level/octave-packages.nix

@@ -56,7 +56,7 @@ makeScope newScope (
   in
   {
 
-    inherit callPackage buildOctavePackage computeRequiredOctavePackages;
+    inherit buildOctavePackage computeRequiredOctavePackages;
 
     inherit (callPackage ../development/interpreters/octave/hooks { })
       writeRequiredOctavePackagesHook