debug! debug! try to print the prefetch-yarn-deps stuff

Signed-off-by: Raito Bezarius <masterancpp@gmail.com>

overlay.nix

@@ -34,7 +34,7 @@ in
   };
 
   # force these onto upstream so we are not regularly rebuilding electron
-  prefetch-yarn-deps = prev.prefetch-yarn-deps.override {
+  prefetch-yarn-deps = (final.lib.trace "overriding: ${toString (builtins.attrNames prev.prefetch-yarn-deps)}" prev.prefetch-yarn-deps).override {
     nix = final.nixVersions.nix_2_18_upstream;
   };
   prefetch-npm-deps = prev.prefetch-npm-deps.override {