$ git clone -n https://src.fedoraproject.org/rpms/golang-x-xerrors.git /var/lib/mock/f45-build-12881-444/root/chroot_tmpdir/scmroot/golang-x-xerrors
Cloning into '/var/lib/mock/f45-build-12881-444/root/chroot_tmpdir/scmroot/golang-x-xerrors'...
$ git fetch origin 27f879e03dad908ac21d00b36bbace9386dd3dcd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-x-xerrors
 * [new ref]         27f879e03dad908ac21d00b36bbace9386dd3dcd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 27f879e Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild