$ git clone -n https://src.fedoraproject.org/rpms/ffmpegthumbs.git /var/lib/mock/f45-build-8929-397/root/chroot_tmpdir/scmroot/ffmpegthumbs
Cloning into '/var/lib/mock/f45-build-8929-397/root/chroot_tmpdir/scmroot/ffmpegthumbs'...
$ git fetch origin 5a0b671c694326206399ddea07cdb71c40aee308:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ffmpegthumbs
 * [new ref]         5a0b671c694326206399ddea07cdb71c40aee308 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5a0b671 Rebuilt for FFmpeg 9