Merge branch 'rr/fmt-merge-msg'

* rr/fmt-merge-msg: t6200-fmt-merge-msg: Exercise '--log' to configure shortlog length t6200-fmt-merge-msg: Exercise 'merge.log' to configure shortlog length merge: Make 'merge.log' an integer or boolean option merge: Make '--log' an integer option for number of shortlog entries fmt_merge_msg: Change fmt_merge_msg API to accept shortlog_len Conflicts: builtin/merge.c