$ git clone -n https://src.fedoraproject.org/rpms/R-brew.git /var/lib/mock/f45-build-5987-345/root/chroot_tmpdir/scmroot/R-brew
Cloning into '/var/lib/mock/f45-build-5987-345/root/chroot_tmpdir/scmroot/R-brew'...
$ git fetch origin 2170bf78010e98c94c37ef04e0fe748839446388:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-brew
 * [new ref]         2170bf78010e98c94c37ef04e0fe748839446388 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2170bf7 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild