$ git clone -n https://src.fedoraproject.org/rpms/rust-gstreamer-sys /var/lib/mock/f42-build-3429033-45391/root/chroot_tmpdir/scmroot/rust-gstreamer-sys
Cloning into '/var/lib/mock/f42-build-3429033-45391/root/chroot_tmpdir/scmroot/rust-gstreamer-sys'...
$ git fetch origin 8d138cc31a7e2eb8f4c67ae397ece26511a586a1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-gstreamer-sys
 * [new ref]         8d138cc31a7e2eb8f4c67ae397ece26511a586a1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8d138cc Update to version 0.23.5; Fixes RHBZ#2333677