octavePackages: buildOctavePackage respects user-provided hooks

octavePackages: Allow user to provide extra steps and information

pkgs/development/interpreters/octave/build-octave-package.nix

@@ -54,7 +54,23 @@
 let
   requiredOctavePackages' = computeRequiredOctavePackages requiredOctavePackages;
 
-in stdenv.mkDerivation {
+  # Must use attrs.nativeBuildInputs before they are removed by the removeAttrs
+  # below, or everything fails.
+  nativeBuildInputs' = [
+    octave
+    writeRequiredOctavePackagesHook
+  ]
+  ++ nativeBuildInputs;
+
+  # This step is required because when
+  # a = { test = [ "a" "b" ]; }; b = { test = [ "c" "d" ]; };
+  # (a // b).test = [ "c" "d" ];
+  # This used to mean that if a package defined extra nativeBuildInputs, it
+  # would override the ones for building an Octave package (the hook and Octave
+  # itself, causing everything to fail.
+  attrs' = builtins.removeAttrs attrs [ "nativeBuildInputs" ];
+
+in stdenv.mkDerivation ({
   packageName = "${fullLibName}";
   # The name of the octave package ends up being
   # "octave-version-package-version"
@@ -77,11 +93,7 @@ in stdenv.mkDerivation {
 
   requiredOctavePackages = requiredOctavePackages';
 
-  nativeBuildInputs = [
-    octave
-    writeRequiredOctavePackagesHook
-  ]
-  ++ nativeBuildInputs;
+  nativeBuildInputs = nativeBuildInputs';
 
   buildInputs = buildInputs ++ requiredOctavePackages';
 
@@ -110,4 +122,4 @@ in stdenv.mkDerivation {
   dontInstall = true;
 
   inherit meta;
-}
+} // attrs')