$ git clone -n https://src.fedoraproject.org/rpms/R-rprojroot.git /var/lib/mock/f45-build-6374-348/root/chroot_tmpdir/scmroot/R-rprojroot
Cloning into '/var/lib/mock/f45-build-6374-348/root/chroot_tmpdir/scmroot/R-rprojroot'...
$ git fetch origin d65bbac248636a06d19494fa681a0f998e9fed67:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-rprojroot
 * [new ref]         d65bbac248636a06d19494fa681a0f998e9fed67 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d65bbac Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild