$ git clone -n https://src.fedoraproject.org/rpms/rust-similar.git /var/lib/mock/f45-build-44970-820/root/chroot_tmpdir/scmroot/rust-similar
Cloning into '/var/lib/mock/f45-build-44970-820/root/chroot_tmpdir/scmroot/rust-similar'...
$ git fetch origin 47adc5f8091d86d2147735e5ff170fb624118a4e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-similar
 * [new ref]         47adc5f8091d86d2147735e5ff170fb624118a4e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 47adc5f Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild