$ git clone -n https://src.fedoraproject.org/rpms/javacc.git /var/lib/mock/f40-build-2227143-53001/root/chroot_tmpdir/scmroot/javacc
Cloning into '/var/lib/mock/f40-build-2227143-53001/root/chroot_tmpdir/scmroot/javacc'...
$ git fetch origin 7cc5d2b797bb116432074fe0d9983eafb753f637:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/javacc
 * [new ref]         7cc5d2b797bb116432074fe0d9983eafb753f637 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7cc5d2b Update javapackages test plan to f40