$ git clone -n https://src.fedoraproject.org/rpms/rust-utf8_iter.git /var/lib/mock/f45-build-45987-830/root/chroot_tmpdir/scmroot/rust-utf8_iter
Cloning into '/var/lib/mock/f45-build-45987-830/root/chroot_tmpdir/scmroot/rust-utf8_iter'...
$ git fetch origin bb509191ce00b63b7d92b3fe29c91a44cac7da9d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-utf8_iter
 * [new ref]         bb509191ce00b63b7d92b3fe29c91a44cac7da9d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bb50919 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild