reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/broonie/ci.git/commit/?id=6ed9d474840a027cb6b1c5c16fbce9ed626c9dc8
        git remote add broonie-ci https://git.kernel.org/pub/scm/linux/kernel/git/broonie/ci.git
        git fetch --no-tags broonie-ci kselftest-clone3-set-tid
        git checkout 6ed9d474840a027cb6b1c5c16fbce9ed626c9dc8
        make W=1 O=/tmp/kselftest headers
        make W=1 O=/tmp/kselftest -C tools/testing/selftests
        make W=1 O=/tmp/kselftest -C tools/testing/selftests/bpf