$ git clone -n https://src.fedoraproject.org/rpms/diffoscope.git /var/lib/mock/f39-build-2201525-51806/root/chroot_tmpdir/scmroot/diffoscope
Cloning into '/var/lib/mock/f39-build-2201525-51806/root/chroot_tmpdir/scmroot/diffoscope'...
$ git fetch origin 1d6e32f376b0609c054d70321ee5b99e86380696:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/diffoscope
 * [new ref]         1d6e32f376b0609c054d70321ee5b99e86380696 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1d6e32f Version 252