$ git clone -n https://src.fedoraproject.org/rpms/git-time-metric.git /var/lib/mock/f42-build-866279-173809/root/chroot_tmpdir/scmroot/git-time-metric
Cloning into '/var/lib/mock/f42-build-866279-173809/root/chroot_tmpdir/scmroot/git-time-metric'...
$ git fetch origin 3500110c72686f84cdd3f96c4fea18b9078897d3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/git-time-metric
 * [new ref]         3500110c72686f84cdd3f96c4fea18b9078897d3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3500110 Rebuild for libgit2 1.8.x