$ git clone -n https://src.fedoraproject.org/rpms/mrcpp.git /var/lib/mock/f38-build-side-42-init-devel-1134059-30351/root/chroot_tmpdir/scmroot/mrcpp
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-1134059-30351/root/chroot_tmpdir/scmroot/mrcpp'...
$ git fetch origin b313a07fa01cf3ba515162ee20c68e1ca4f7bd31:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mrcpp
 * [new ref]         b313a07fa01cf3ba515162ee20c68e1ca4f7bd31 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b313a07 Update to 1.4.2.