$ git clone -n https://src.fedoraproject.org/rpms/rust-gstreamer.git /var/lib/mock/f39-build-1627262-39368/root/chroot_tmpdir/scmroot/rust-gstreamer
Cloning into '/var/lib/mock/f39-build-1627262-39368/root/chroot_tmpdir/scmroot/rust-gstreamer'...
$ git fetch origin 55d818454664c2176a790b807ca9c4b09ab52002:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-gstreamer
 * [new ref]         55d818454664c2176a790b807ca9c4b09ab52002 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 55d8184 Update to version 0.21.1; Fixes RHBZ#2241362