buildPython*: extend overrideStdenvCompat to fixed-point arguments

with `passthru.__stdenvPythonCompat`

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

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

@@ -54,6 +54,7 @@ let
       lib.mirrorFunctionArgs f (
         args:
         let
+          result = f args;
           getName = x: x.pname or (lib.getName (x.name or "<unnamed>"));
           applyMsgStdenvArg =
             name:
@@ -62,12 +63,18 @@ let
                 buildPythonPackage.override { stdenv = customStdenv; } { }
             '';
         in
-        if !(lib.isFunction args) && (args ? stdenv) then
+        if lib.isFunction args && result ? __stdenvPythonCompat then
+          # Less reliable, as constructing with the wrong `stdenv` might lead to evaluation errors in the package definition.
+          f'.override { stdenv = applyMsgStdenvArg (getName result) result.__stdenvPythonCompat; } (
+            finalAttrs: removeAttrs (args finalAttrs) [ "stdenv" ]
+          )
+        else if (!lib.isFunction args) && (args ? stdenv) then
+          # More reliable, but only works when args is not `(finalAttrs: { })`
           f'.override { stdenv = applyMsgStdenvArg (getName args) args.stdenv; } (
             removeAttrs args [ "stdenv" ]
           )
         else
-          f args
+          result
       )
       // {
         # Preserve the effect of overrideStdenvCompat when calling `buildPython*.override`.