$ git clone -n https://src.fedoraproject.org/rpms/subnetcalc.git /var/lib/mock/f43-build-59140210-6571288/root/chroot_tmpdir/scmroot/subnetcalc
Cloning into '/var/lib/mock/f43-build-59140210-6571288/root/chroot_tmpdir/scmroot/subnetcalc'...
$ git fetch origin 0e8e76e6156d68cf33b294c7c4d75ad2865afeb8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/subnetcalc
 * [new ref]         0e8e76e6156d68cf33b294c7c4d75ad2865afeb8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0e8e76e Update to 2.6.3