cpython: fix permissions on venv activation scripts

Previously these ended up without u+w permissions which meant they could
not be regenerated, which was hugely annoying when these venvs were for
example created and recreated in a nix-shell.

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

@@ -190,6 +190,10 @@ in with passthru; stdenv.mkDerivation {
     # (since it will do a futile invocation of gcc (!) to find
     # libuuid, slowing down program startup a lot).
     (./. + "/${sourceVersion.major}.${sourceVersion.minor}/no-ldconfig.patch")
+    # Make sure that the virtualenv activation scripts are
+    # owner-writable, so venvs can be recreated without permission
+    # errors.
+    ./virtualenv-permissions.patch
   ] ++ optionals mimetypesSupport [
     # Make the mimetypes module refer to the right file
     ./mimetypes.patch