makeOverridablePythonPackage: take care of overrideAttrs

Make it possible to mix overridePythonAttrs and overrideAttrs, i.e.
((<pkg>.overrideAttrs (_: { foo = "a"; })).overridePythonAttrs (_: { })).foo now works

Co-authored-by: Matt Sturgeon <matt@sturgeon.me.uk>

pkgs/development/interpreters/python/python-packages-base.nix

@@ -14,6 +14,9 @@ let
 
   # Derivations built with `buildPythonPackage` can already be overridden with `override`, `overrideAttrs`, and `overrideDerivation`.
   # This function introduces `overridePythonAttrs` and it overrides the call to `buildPythonPackage`.
+  #
+  # Overridings specified through `overridePythonAttrs` will always be applied
+  # before those specified by `overrideAttrs`, even if invoked after them.
   makeOverridablePythonPackage =
     f:
     lib.mirrorFunctionArgs f (
@@ -26,6 +29,8 @@ let
         result
         // {
           overridePythonAttrs = newArgs: makeOverridablePythonPackage f (overrideWith newArgs);
+          overrideAttrs =
+            newArgs: makeOverridablePythonPackage (args: (f args).overrideAttrs newArgs) origArgs;
         }
       else
         result

pkgs/test/overriding.nix

@@ -407,6 +407,14 @@ let
         p.overridePythonAttrs (previousAttrs: {
           overridePythonAttrsFlag = previousAttrs.overridePythonAttrsFlag or 0 + 1;
         });
+      overrideAttrsFooBar =
+        drv:
+        drv.overrideAttrs (
+          finalAttrs: previousAttrs: {
+            FOO = "a";
+            BAR = finalAttrs.FOO;
+          }
+        );
     in
     {
       overridePythonAttrs = {
@@ -418,6 +426,37 @@ let
           (applyOverridePythonAttrs (applyOverridePythonAttrs python-package-stub)).overridePythonAttrsFlag;
         expected = 2;
       };
+      overrideAttrs-overridePythonAttrs-test-overrideAttrs = {
+        expr = {
+          inherit (applyOverridePythonAttrs (overrideAttrsFooBar python-package-stub))
+            FOO
+            BAR
+            ;
+        };
+        expected = {
+          FOO = "a";
+          BAR = "a";
+        };
+      };
+      overrideAttrs-overridePythonAttrs-test-overridePythonAttrs = {
+        expr =
+          (applyOverridePythonAttrs (overrideAttrsFooBar python-package-stub)) ? overridePythonAttrsFlag;
+        expected = true;
+      };
+      overrideAttrs-overridePythonAttrs-test-commutation = {
+        expr = overrideAttrsFooBar (applyOverridePythonAttrs python-package-stub);
+        expected = applyOverridePythonAttrs (overrideAttrsFooBar python-package-stub);
+      };
+      chain-of-overrides = rec {
+        expr = lib.pipe python-package-stub [
+          (p: p.overrideAttrs { inherit (expected) a; })
+          (p: p.overridePythonAttrs { inherit (expected) b; })
+          (p: p.overrideAttrs { inherit (expected) c; })
+          (p: p.overridePythonAttrs { inherit (expected) d; })
+          (builtins.intersectAttrs expected)
+        ];
+        expected = lib.genAttrs [ "a" "b" "c" "d" ] lib.id;
+      };
     };
 
 in