python3Packages.buildPythonPackage: default to __structuredAttrs = true (#543976)

doc/release-notes/rl-2611.section.md

@@ -82,6 +82,8 @@
 
 - `nix-serve-ng` (and `haskellPackages.nix-serve-ng`) is now built against Lix instead of CppNix, following upstream which has switched to Lix as its supported Nix implementation.
 
+- `buildPythonPackage` and `buildPythonApplication` now set `__structuredAttrs = true` by default. You can explicitly set `__structuredAttrs = false` in packages broken by this change.
+
 - Linux kernel configuration has been moved out of the `linux-kernel` field of the platform structure into the kernel builders:
   - `linux-kernel.name` has been removed.
   - `linux-kernel.target` is available as the `target` parameter and passthru attribute on the kernel builders.

pkgs/development/interpreters/python/mk-python-derivation.nix

@@ -207,6 +207,8 @@ lib.extendMkDerivation {
 
       doCheck ? true,
 
+      __structuredAttrs ? true,
+
       ...
     }@attrs:
 
@@ -387,7 +389,7 @@ lib.extendMkDerivation {
           python
         ];
 
-      inherit strictDeps;
+      inherit __structuredAttrs strictDeps;
 
       env = {
         LANG = "${if python.stdenv.hostPlatform.isDarwin then "en_US" else "C"}.UTF-8";