ag/merge-strategies-in-c, was Re: What's cooking in git.git (Mar 2021, #07; Mon, 22)

> * ag/merge-strategies-in-c (2021-03-17) 15 commits
>  - sequencer: use the "octopus" merge strategy without forking
>  - sequencer: use the "resolve" strategy without forking
>  - merge: use the "octopus" strategy without forking
>  - merge: use the "resolve" strategy without forking
>  - merge-octopus: rewrite in C
>  - merge-recursive: move better_branch_name() to merge.c
>  - merge-resolve: rewrite in C
>  - merge-one-file: rewrite in C
>  - update-index: move add_cacheinfo() to read-cache.c
>  - merge-index: add a new way to invoke `git-merge-one-file'
>  - merge-index: drop the index
>  - merge-index: libify merge_one_path() and merge_all()
>  - t6060: add tests for removed files
>  - t6060: modify multiple files to expose a possible issue with merge-index
>  - t6407: modernise tests
>
>  The resolve and octopus merge strategy backends have been rewritten
>  in C.
>
>  Ready?