$ git clone -n https://src.fedoraproject.org/rpms/rust-downcast.git /var/lib/mock/f45-build-41420-782/root/chroot_tmpdir/scmroot/rust-downcast
Cloning into '/var/lib/mock/f45-build-41420-782/root/chroot_tmpdir/scmroot/rust-downcast'...
$ git fetch origin d169268870417cfb1ad9384bf21d91f156a79b40:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-downcast
 * [new ref]         d169268870417cfb1ad9384bf21d91f156a79b40 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d169268 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild