ref: e03915a9f7d8c040c3b7f4e8de4f69f62aeefc99 dir: /sys/src/cmd/diff/test/merge-t3.expected/
1 2 3 4 <<<<<<<<<< merge-t3.l y ========== original 5 ========== merge-t3.r x >>>>>>>>>> 6 7 8 9 10