$ git clone -n https://src.fedoraproject.org/rpms/rust-gstreamer-sys.git /var/lib/mock/f39-build-1637827-40017/root/chroot_tmpdir/scmroot/rust-gstreamer-sys
Cloning into '/var/lib/mock/f39-build-1637827-40017/root/chroot_tmpdir/scmroot/rust-gstreamer-sys'...
$ git fetch origin dff255f564444da00788acaa8ace1dd99652dedc:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-gstreamer-sys
 * [new ref]         dff255f564444da00788acaa8ace1dd99652dedc -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dff255f Update to version 0.21.1; Fixes RHBZ#2242112