Set MOD_DIR correctly

hack/module.sh

@@ -51,10 +51,10 @@ function with_modules() {
   for mod_file in $(find . -maxdepth 4 -name go.mod | sort); do
     mod_dir="$(dirname "${mod_file}")"
     (
-      export MOD_DIR="$(pwd)"
-      echo "=> " && \
-      echo "   cd ${mod_dir} && ${cmd}" && \
-      cd "${mod_dir}" && ${cmd}
+      export MOD_DIR
+      echo "=> "
+      echo "   cd ${mod_dir} && ${cmd}"
+      cd "${mod_dir}" && MOD_DIR="$(pwd)" && ${cmd}
     )
   done
   popd