reproduce (this is a W=1 build):
        git checkout next-20250626
        b4 shazam https://lore.kernel.org/r/20250627091914.100715-9-jth@kernel.org
        # 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 fs/btrfs/