$ git clone -n https://src.fedoraproject.org/rpms/xcalc.git /var/lib/mock/f45-build-38624-726/root/chroot_tmpdir/scmroot/xcalc
Cloning into '/var/lib/mock/f45-build-38624-726/root/chroot_tmpdir/scmroot/xcalc'...
$ git fetch origin 4a525d3caf8af572c0d209b67825a4d5a15b88b9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xcalc
 * [new ref]         4a525d3caf8af572c0d209b67825a4d5a15b88b9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4a525d3 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild