Fix root path resolution on PCK file

core/io/file_access_pack.cpp

@@ -409,6 +409,8 @@ Error DirAccessPack::change_dir(String p_dir) {
 
 	nd=nd.simplify_path();
 
+	if (nd == "") nd = ".";
+
 	if (nd.begins_with("/")) {
 		nd=nd.replace_first("/","")	;
 		absolute=true;