reproduce (this is a W=1 build):
        git checkout 432279e0c75d8281a75ace15d6039cb895a5aa86
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash