$ git clone -n https://src.fedoraproject.org/rpms/R-backports.git /var/lib/mock/f39-build-1495925-34546/root/chroot_tmpdir/scmroot/R-backports
Cloning into '/var/lib/mock/f39-build-1495925-34546/root/chroot_tmpdir/scmroot/R-backports'...
$ git fetch origin 42e9f1bee2ea0cf2d30390b7d38f939f5d3a45c4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-backports
 * [new ref]         42e9f1bee2ea0cf2d30390b7d38f939f5d3a45c4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 42e9f1b Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild