$ git clone -n https://src.fedoraproject.org/rpms/rust-maildir.git /var/lib/mock/f41-build-side-1-3134855-39763/root/chroot_tmpdir/scmroot/rust-maildir
Cloning into '/var/lib/mock/f41-build-side-1-3134855-39763/root/chroot_tmpdir/scmroot/rust-maildir'...
$ git fetch origin 884410ad0777ad2b69c477d0cc2f682dccfff59c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-maildir
 * [new ref]         884410ad0777ad2b69c477d0cc2f682dccfff59c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 884410a unused leaf package for more than two release cycles