pythonMinimal: don't include site-customise

Experimenting with patching the site-customize file causes mass
rebuilds for no reason.

pkgs/development/interpreters/python/cpython/default.nix

@@ -28,6 +28,7 @@
 , stripTkinter ? false
 , rebuildBytecode ? true
 , stripBytecode ? false
+, includeSiteCustomize ? true
 }:
 
 assert x11Support -> tcl != null
@@ -237,7 +238,7 @@ in with passthru; stdenv.mkDerivation {
     '' + optionalString stripTests ''
     # Strip tests
     rm -R $out/lib/python*/test $out/lib/python*/**/test{,s}
-    '' + ''
+    '' + optionalString includeSiteCustomize ''
     # Include a sitecustomize.py file
     cp ${../sitecustomize.py} $out/${sitePackages}/sitecustomize.py
     '' + optionalString rebuildBytecode ''