$ git clone -n https://src.fedoraproject.org/rpms/rust-gstreamer-base.git /var/lib/mock/f38-build-side-43-rust-devel-1401376-31168/root/chroot_tmpdir/scmroot/rust-gstreamer-base
Cloning into '/var/lib/mock/f38-build-side-43-rust-devel-1401376-31168/root/chroot_tmpdir/scmroot/rust-gstreamer-base'...
$ git fetch origin cfcbc646fdca058ff912110622c3f02f904f78a9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-gstreamer-base
 * [new ref]         cfcbc646fdca058ff912110622c3f02f904f78a9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cfcbc64 Update to 0.21.0