$ git clone -n https://src.fedoraproject.org/rpms/rust-gstreamer.git /var/lib/mock/f42-build-side-1-3512442-46069/root/chroot_tmpdir/scmroot/rust-gstreamer
Cloning into '/var/lib/mock/f42-build-side-1-3512442-46069/root/chroot_tmpdir/scmroot/rust-gstreamer'...
$ git fetch origin e151c46aa882dbb6d6b56a8b712e3e7ff8072b08:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-gstreamer
 * [new ref]         e151c46aa882dbb6d6b56a8b712e3e7ff8072b08 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e151c46 Update to ron 0.9