"git diff --stat" miscounted the total number of changed lines when
binary files were involved and hidden beyond --stat-count. It also
miscounted the total number of changed files when there were
unmerged paths.
* lt/diff-stat-show-0-lines:
t4049: refocus tests
diff --shortstat: do not count "unmerged" entries
diff --stat: do not count "unmerged" entries
diff --stat: move the "total count" logic to the last loop
diff --stat: use "file" temporary variable to refer to data->files[i]
diff --stat: status of unmodified pair in diff-q is not zero
test: add failing tests for "diff --stat" to t4049