set up check shell

Author: brainrake

flake.nix

@@ -366,7 +366,11 @@
             ++ [ self.devShell.${system}.inputDerivation self.devShell.${system}.nativeBuildInputs ];
         } ''
           cd ${self}
-          IN_NIX_SHELL=true make format_check cabalfmt_check nixpkgsfmt_check lint
+          export LC_CTYPE=C.UTF-8
+          export LC_ALL=C.UTF-8
+          export LANG=C.UTF-8
+          export IN_NIX_SHELL='pure'
+          make format_check cabalfmt_check nixpkgsfmt_check lint
           mkdir $out
         '');