Submodules UX overhaul update (was: What's cooking in git.git (Nov 2021, #06; Wed, 24))

> --------------------------------------------------
> [Stalled]
> 
> * ar/submodule-update (2021-10-13) 9 commits
>  . submodule--helper: rename helper functions
>  . submodule--helper: remove unused helpers
>  . submodule: move core cmd_update() logic to C
>  . submodule--helper: run update using child process struct
>  . submodule--helper: allow setting superprefix for init_submodule()
>  . submodule--helper: refactor get_submodule_displaypath()
>  . submodule--helper: rename helpers for update-clone
>  . submodule--helper: get remote names from any repository
>  . submodule--helper: split up ensure_core_worktree()
> 
>  Rewrite of "git submodule update" in C.
> 
>  Kicked out of 'seen' to make room for es/superproject-aware-submodules
>  which is among the topics this topic stomps on.

> --------------------------------------------------
> [Cooking]
> 
> * gc/remote-with-fewer-static-global-variables (2021-11-18) 5 commits
>  - remote: die if branch is not found in repository
>  - remote: remove the_repository->remote_state from static methods
>  - remote: use remote_state parameter internally
>  - remote: move static variables into per-repository struct
>  - t5516: add test case for pushing remote refspecs
> 
>  Code clean-up to eventually allow information on remotes defined
>  for an arbitrary repository to be read.
> 
>  Will merge to 'next'.

> * ab/config-based-hooks-2 (2021-11-24) 18 commits
>  - run-command: remove old run_hook_{le,ve}() hook API
>  - receive-pack: convert push-to-checkout hook to hook.h
>  - read-cache: convert post-index-change to use hook.h
>  - commit: convert {pre-commit,prepare-commit-msg} hook to hook.h
>  - git-p4: use 'git hook' to run hooks
>  - send-email: use 'git hook run' for 'sendemail-validate'
>  - git hook run: add an --ignore-missing flag
>  - hooks: convert worktree 'post-checkout' hook to hook library
>  - hooks: convert non-worktree 'post-checkout' hook to hook library
>  - merge: convert post-merge to use hook.h
>  - am: convert applypatch-msg to use hook.h
>  - rebase: convert pre-rebase to use hook.h
>  - hook API: add a run_hooks_l() wrapper
>  - am: convert {pre,post}-applypatch to use hook.h
>  - gc: use hook library for pre-auto-gc hook
>  - hook API: add a run_hooks() wrapper
>  - hook: add 'run' subcommand
>  - Merge branch 'ab/config-based-hooks-1' into ab/config-based-hooks-2
> 
>  More "config-based hooks".

> * js/branch-track-inherit (2021-11-18) 1 commit
>  - branch: add flags and config to inherit tracking
> 
>  "git -c branch.autosetupmerge=inherit branch new old" makes "new"
>  to have the same upstream as the "old" branch, instead of marking
>  "old" itself as its upstream.

> * es/superproject-aware-submodules (2021-11-18) 5 commits
>  - submodule: use config to find superproject worktree
>  - submodule: record superproject gitdir during 'update'
>  - submodule: record superproject gitdir during absorbgitdirs
>  - introduce submodule.superprojectGitDir record
>  - t7400-submodule-basic: modernize inspect() helper
> 
>  A configuration variable in a submodule points at the location of
>  the superproject it is bound to (RFC).