ps/stash-in-c, was Re: What's cooking in git.git (Dec 2018, #02; Fri, 28)

> * ps/stash-in-c (2018-11-26) 22 commits
>  . stash: replace all `write-tree` child processes with API calls
>  . stash: optimize `get_untracked_files()` and `check_changes()`
>  . stash: convert `stash--helper.c` into `stash.c`
>  . stash: convert save to builtin
>  . stash: make push -q quiet
>  . stash: convert push to builtin
>  . stash: convert create to builtin
>  . stash: convert store to builtin
>  . stash: convert show to builtin
>  . stash: convert list to builtin
>  . stash: convert pop to builtin
>  . stash: convert branch to builtin
>  . stash: convert drop and clear to builtin
>  . stash: convert apply to builtin
>  . stash: mention options in `show` synopsis
>  . stash: add tests for `git stash show` config
>  . stash: rename test cases to be more descriptive
>  . t3903: modernize style
>  . stash: improve option parsing test coverage
>  . strbuf.c: add `strbuf_insertf()` and `strbuf_vinsertf()`
>  . strbuf.c: add `strbuf_join_argv()`
>  . sha1-name.c: add `get_oidf()` which acts like `get_oid()`
> 
>  "git stash" rewritten in C.
> 
>  Expecting a reroll, probably on top of the sd/stash-wo-user-name
>  topic after it stabilizes, with an escape hatch like the one in
>  "rebase in C".