Merge pull request #265570 from amjoseph-nixpkgs/pyqtwebengine-take-different-python3

pkgs/development/interpreters/python/passthrufun.nix

···
       overrides = packageOverrides;
       python = self;
     });
+  pythonOnBuildForHost_overridden =
+    pythonOnBuildForHost.override { inherit packageOverrides; self = pythonOnBuildForHost_overridden; };
 in rec {
     isPy27 = pythonVersion == "2.7";
     isPy37 = pythonVersion == "3.7";
···
     pythonAtLeast = lib.versionAtLeast pythonVersion;
     pythonOlder = lib.versionOlder pythonVersion;
     inherit hasDistutilsCxxPatch;
-    # TODO: rename to pythonOnBuild
+    # TODO: deprecate
     # Not done immediately because its likely used outside Nixpkgs.
-    pythonForBuild = pythonOnBuildForHost.override { inherit packageOverrides; self = pythonForBuild; };
+    pythonForBuild = pythonOnBuildForHost_overridden;
+    pythonOnBuildForHost = pythonOnBuildForHost_overridden;
 
     tests = callPackage ./tests.nix {
       python = self;

pkgs/development/python-modules/pyqtwebengine/default.nix

···
   ] ++ lib.optionals (stdenv.buildPlatform == stdenv.hostPlatform) [
     sip
   ] ++ lib.optionals (stdenv.buildPlatform != stdenv.hostPlatform) [
-    buildPackages.python3Packages.sip
+    python.pythonOnBuildForHost.pkgs.sip
   ] ++ [
     qtbase
     qtsvg