$ git clone -n https://src.fedoraproject.org/rpms/ffmpegthumbnailer.git /var/lib/mock/f45-build-8939-397/root/chroot_tmpdir/scmroot/ffmpegthumbnailer
Cloning into '/var/lib/mock/f45-build-8939-397/root/chroot_tmpdir/scmroot/ffmpegthumbnailer'...
$ git fetch origin 9f809129281c25bb398a76f949fb4f0fa9a8a85f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ffmpegthumbnailer
 * [new ref]         9f809129281c25bb398a76f949fb4f0fa9a8a85f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9f80912 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild