reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git/commit/?id=2a52e4d89847745f8ab76265199a371ef5e7f93f
        git remote add robh https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git
        git fetch --no-tags robh for-next
        git checkout 2a52e4d89847745f8ab76265199a371ef5e7f93f
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash lib/