$ git clone -n https://src.fedoraproject.org/rpms/R-mockr.git /var/lib/mock/f45-build-6244-347/root/chroot_tmpdir/scmroot/R-mockr
Cloning into '/var/lib/mock/f45-build-6244-347/root/chroot_tmpdir/scmroot/R-mockr'...
$ git fetch origin c94af755843e0273732cf508f05b2f9327503651:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-mockr
 * [new ref]         c94af755843e0273732cf508f05b2f9327503651 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c94af75 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild