$ git clone -n https://src.fedoraproject.org/rpms/jopt-simple.git /var/lib/mock/f40-build-2686608-68066/root/chroot_tmpdir/scmroot/jopt-simple
Cloning into '/var/lib/mock/f40-build-2686608-68066/root/chroot_tmpdir/scmroot/jopt-simple'...
$ git fetch origin 4db2d9bcc04d35f9f63e91294864631dfa8868d5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/jopt-simple
 * [new ref]         4db2d9bcc04d35f9f63e91294864631dfa8868d5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4db2d9b Set Java source/target to 1.8