$ git clone -n https://src.fedoraproject.org/rpms/rust-rand_chacha.git /var/lib/mock/f45-build-44218-811/root/chroot_tmpdir/scmroot/rust-rand_chacha
Cloning into '/var/lib/mock/f45-build-44218-811/root/chroot_tmpdir/scmroot/rust-rand_chacha'...
$ git fetch origin 191468dc416277a184c6f8eab543ad51775e32e0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-rand_chacha
 * [new ref]         191468dc416277a184c6f8eab543ad51775e32e0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 191468d Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild