$ git clone -n https://src.fedoraproject.org/rpms/ffmpegthumbs.git /var/lib/mock/f42-build-3403669-45135/root/chroot_tmpdir/scmroot/ffmpegthumbs
Cloning into '/var/lib/mock/f42-build-3403669-45135/root/chroot_tmpdir/scmroot/ffmpegthumbs'...
$ git fetch origin f12f2a5f01475250094aed6f7050fc999887a0f9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ffmpegthumbs
 * [new ref]         f12f2a5f01475250094aed6f7050fc999887a0f9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f12f2a5 24.12.3