$ git clone -n https://src.fedoraproject.org/rpms/R-pkgload.git /var/lib/mock/f45-build-6303-347/root/chroot_tmpdir/scmroot/R-pkgload
Cloning into '/var/lib/mock/f45-build-6303-347/root/chroot_tmpdir/scmroot/R-pkgload'...
$ git fetch origin 0a3b266e9be51cf96880f16b1ecbd14b3240e7f8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-pkgload
 * [new ref]         0a3b266e9be51cf96880f16b1ecbd14b3240e7f8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0a3b266 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild