$ git clone -n https://src.fedoraproject.org/rpms/ffmpeg.git /var/lib/mock/f41-build-858511-168433/root/chroot_tmpdir/scmroot/ffmpeg
Cloning into '/var/lib/mock/f41-build-858511-168433/root/chroot_tmpdir/scmroot/ffmpeg'...
$ git fetch origin aa1f2113d7cc2d393529bccdc090fb5a37f9b89f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ffmpeg
 * [new ref]         aa1f2113d7cc2d393529bccdc090fb5a37f9b89f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at aa1f211 Properly enable aribb24/libaribcaption