$ git clone -n https://src.fedoraproject.org/rpms/borgbackup.git /var/lib/mock/f39-build-1489663-34501/root/chroot_tmpdir/scmroot/borgbackup
Cloning into '/var/lib/mock/f39-build-1489663-34501/root/chroot_tmpdir/scmroot/borgbackup'...
$ git fetch origin dbfb4fe29416fafe25a8e83a8159b1513d479e82:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/borgbackup
 * [new ref]         dbfb4fe29416fafe25a8e83a8159b1513d479e82 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dbfb4fe add missing sources