$ git clone -n https://src.fedoraproject.org/rpms/proftpd.git /var/lib/mock/f39-build-1459509-33138/root/chroot_tmpdir/scmroot/proftpd
Cloning into '/var/lib/mock/f39-build-1459509-33138/root/chroot_tmpdir/scmroot/proftpd'...
$ git fetch origin a004b030755cf3751661121771f456d6a2161e75:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/proftpd
 * [new ref]         a004b030755cf3751661121771f456d6a2161e75 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a004b03 Update to 1.3.8a