$ git clone -n https://src.fedoraproject.org/rpms/diffoscope.git /var/lib/mock/f39-build-2348468-60143/root/chroot_tmpdir/scmroot/diffoscope
Cloning into '/var/lib/mock/f39-build-2348468-60143/root/chroot_tmpdir/scmroot/diffoscope'...
$ git fetch origin 9ce901e0a96fa16ee47092ca0460f39003a322f7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/diffoscope
 * [new ref]         9ce901e0a96fa16ee47092ca0460f39003a322f7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9ce901e Version 255