elixir: use env shebang only on Darwin

pkgs/development/interpreters/elixir/generic-builder.nix

@@ -57,6 +57,16 @@ let
       true
     else
       versionOlder (versions.major (getVersion erlang)) maxShiftMajor;
+
+  elixirShebang =
+    if stdenv.hostPlatform.isDarwin then
+      # Darwin disallows shebang scripts from using other scripts as their
+      # command. Use env as an intermediary instead of calling elixir directly
+      # (another shebang script).
+      # See https://github.com/NixOS/nixpkgs/pull/9671
+      "${coreutils}/bin/env $out/bin/elixir"
+    else
+      "$out/bin/elixir";
 in
 assert assertMsg (versionAtLeast (getVersion erlang) minimumOTPVersion) compatibilityMsg;
 assert assertMsg maxAssert compatibilityMsg;
@@ -104,7 +114,7 @@ stdenv.mkDerivation ({
     done
 
     substituteInPlace $out/bin/mix \
-      --replace "/usr/bin/env elixir" "${coreutils}/bin/env $out/bin/elixir"
+      --replace "/usr/bin/env elixir" "${elixirShebang}"
   '';
 
   pos = builtins.unsafeGetAttrPos "sha256" args;