Since http://hg.slitaz.org/wok/rev/f3c6288fb955 the build bot verify that each package is cooked after all necessary packages to build it including the toolchain (http://hg.slitaz.org/wok/rev/7040bf60917f). The toolchain has changed with GCC 4.5.1 and every package had to be recooked. Additionnal passes are done to ensure that packages are built in the right order. Packages with a big BUILD_DEPENDS may need many passes...