$ git clone -n https://src.fedoraproject.org/rpms/rust-yasna.git /var/lib/mock/f45-build-46269-832/root/chroot_tmpdir/scmroot/rust-yasna
Cloning into '/var/lib/mock/f45-build-46269-832/root/chroot_tmpdir/scmroot/rust-yasna'...
$ git fetch origin a49d46c0a9cb5ae86d690b61aa4ec721b7065c86:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-yasna
 * [new ref]         a49d46c0a9cb5ae86d690b61aa4ec721b7065c86 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a49d46c Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild