$ git clone -n https://src.fedoraproject.org/rpms/rng-tools.git /var/lib/mock/f42-build-863105-171404/root/chroot_tmpdir/scmroot/rng-tools
Cloning into '/var/lib/mock/f42-build-863105-171404/root/chroot_tmpdir/scmroot/rng-tools'...
$ git fetch origin 0bfe851d72b1cd17ceb4a7317564bb164c229ea3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rng-tools
 * [new ref]         0bfe851d72b1cd17ceb4a7317564bb164c229ea3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0bfe851 Rebuild for Jansson 2.14