I enhanced the reproducer to find that I can still trigger this issue when I just keep the first 154 bytes of one file and 17 of the other, but not with less. This makes me suspect mime-type detection to be involved. and indeed filterdiff strings pkgs.*/*noarch.rpm shows noarch-suse-linux directory +TrueType Font data, 19 tables, 1st "Feat" utf-8 The version built on 1 core lacks the .otf metadata.