ruby-modules: Import gemset if it's a path OR a string. (#38959)

This fixes the bug introduced by 8686b98612 which broke bundlerEnv
exprs when gemdir was a string (thus making gemset a string by
`gemset = gemdir + "/gemset.nix"`) which made it being treated as a
set.

pkgs/development/ruby-modules/bundled-common/default.nix

@@ -29,7 +29,7 @@ with  import ./functions.nix { inherit lib gemConfig; };
 let
   gemFiles = bundlerFiles args;
 
-  importedGemset = if builtins.typeOf gemFiles.gemset == "path"
+  importedGemset = if builtins.typeOf gemFiles.gemset != "set"
     then import gemFiles.gemset
     else gemFiles.gemset;