$ git clone -n https://src.fedoraproject.org/rpms/deltarpm.git /var/lib/mock/f41-build-846071-162958/root/chroot_tmpdir/scmroot/deltarpm
Cloning into '/var/lib/mock/f41-build-846071-162958/root/chroot_tmpdir/scmroot/deltarpm'...
$ git fetch origin 23f871cd40bbbe05eb2fe92ba0f660a6bf0cf054:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/deltarpm
 * [new ref]         23f871cd40bbbe05eb2fe92ba0f660a6bf0cf054 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 23f871c New upstream release 3.6.4, fixes rhbz#2303707