$ git clone -n https://src.fedoraproject.org/rpms/basesystem.git /var/lib/mock/f42-build-3528131-46299/root/chroot_tmpdir/scmroot/basesystem
Cloning into '/var/lib/mock/f42-build-3528131-46299/root/chroot_tmpdir/scmroot/basesystem'...
$ git fetch origin b8cf9971f2d68d620f49e9adb751b3065b66ccde:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/basesystem
 * [new ref]         b8cf9971f2d68d620f49e9adb751b3065b66ccde -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b8cf997 Rebuilt for https://fedoraproject.org/wiki/Fedora_42_Mass_Rebuild