an attempt at fixing caching

bin/compile

@@ -214,7 +214,7 @@ bpwatch start dump_cache
   mkdir -p $CACHE_DIR/$CACHED_DIR
   for dir in $CACHED_DIRS; do
     rm -rf $CACHE_DIR/$dir
-    cp -R $dir $CACHE_DIR/
+    cp -R $dir $CACHE_DIR/ 2>/dev/null
   done
 bpwatch stop dump_cache