$ git clone -n https://src.fedoraproject.org/rpms/R-Rmpfr /var/lib/mock/f39-build-1586852-38212/root/chroot_tmpdir/scmroot/R-Rmpfr
Cloning into '/var/lib/mock/f39-build-1586852-38212/root/chroot_tmpdir/scmroot/R-Rmpfr'...
$ git fetch origin 87f30f19ec2827c83b2a380a718c8beb5a826f5d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-Rmpfr
 * [new ref]         87f30f19ec2827c83b2a380a718c8beb5a826f5d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 87f30f1 Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild