$ git clone -n https://src.fedoraproject.org/rpms/esmtp.git /var/lib/mock/f41-build-884552-16596/root/chroot_tmpdir/scmroot/esmtp
Cloning into '/var/lib/mock/f41-build-884552-16596/root/chroot_tmpdir/scmroot/esmtp'...
$ git fetch origin f40477649edff488cbca3373dfbfc149d5cea5a5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/esmtp
 * [new ref]         f40477649edff488cbca3373dfbfc149d5cea5a5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f404776 Eliminate use of obsolete %patchN syntax (#2283636)