# File lib/gitlab_git/diff.rb, line 23
        def between(repo, head, base, options = {}, *paths)
          straight = options.delete(:straight) || false

          common_commit = if straight
                            base
                          else
                            # Only show what is new in the source branch
                            # compared to the target branch, not the other way
                            # around. The linex below with merge_base is
                            # equivalent to diff with three dots (git diff
                            # branch1...branch2) From the git documentation:
                            # "git diff A...B" is equivalent to "git diff
                            # $(git-merge-base A B) B"
                            repo.merge_base_commit(head, base)
                          end

          options ||= {}
          actual_options = filter_diff_options(options)
          repo.diff(common_commit, head, actual_options, *paths)
        end