$ git clone -n https://src.fedoraproject.org/rpms/R-IRkernel.git /var/lib/mock/f39-build-1510407-35494/root/chroot_tmpdir/scmroot/R-IRkernel
Cloning into '/var/lib/mock/f39-build-1510407-35494/root/chroot_tmpdir/scmroot/R-IRkernel'...
$ git fetch origin 18e9e35881962662313348ae946367b9c22fa4a7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-IRkernel
 * [new ref]         18e9e35881962662313348ae946367b9c22fa4a7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 18e9e35 Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild