fix file cut down for side-by-side diff

Created by: skv-headless

For ex: https://gitlab.com/gitlab-org/gitlab-ce/commit/664112b47eb40386f8fa982a748e279a1a5039e2?view=parallel#diff-3 app/mailers/notify.rb - 126 real lines https://gitlab.com/gitlab-org/gitlab-ce/commit/6947d3c0baba7fd68e8373892c6fdad73e0c0457?view=parallel#diff-0 header.scss - 272 real lines https://gitlab.com/gitlab-org/gitlab-ce/commit/00455a478b1b8e0dbc927729cdd60accac635a95?view=parallel#diff-0 milestones_controller.rb - 57 real lines