$ git clone -n https://src.fedoraproject.org/rpms/gstreamer1-plugin-libav.git /var/lib/mock/f40-build-787953-134971/root/chroot_tmpdir/scmroot/gstreamer1-plugin-libav
Cloning into '/var/lib/mock/f40-build-787953-134971/root/chroot_tmpdir/scmroot/gstreamer1-plugin-libav'...
$ git fetch origin 3a8f28c7113f4ba12a88300f5075c8082880002f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gstreamer1-plugin-libav
 * [new ref]         3a8f28c7113f4ba12a88300f5075c8082880002f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3a8f28c 1.22.9