Added 2 minutes later
Although, I'll take a look now; maybe there's a parameter somewhere that's explicitly defined.
Added 4 minutes later
Here, try this. Open the map archive with WinRAR. Go through the directories to the very end. In the map-tag.xdb file, change the CustomGameMap parameter from true to false. Then, in theory, all its differences from a brand-new map that hasn't been edited in the editor will disappear. Except for the commands, of course.