$ git clone -n https://src.fedoraproject.org/rpms/rust-mio0.8.git /var/lib/mock/f45-build-43253-801/root/chroot_tmpdir/scmroot/rust-mio0.8
Cloning into '/var/lib/mock/f45-build-43253-801/root/chroot_tmpdir/scmroot/rust-mio0.8'...
$ git fetch origin b089b78293ffce522a4ec0702580b7881614a0c8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-mio0.8
 * [new ref]         b089b78293ffce522a4ec0702580b7881614a0c8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b089b78 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild