The final step of rewriting "rebase -i" in C.

* pk/rebase-in-c-6-final:
  rebase: default to using the builtin rebase

"rebase" that has been rewritten learns the new calling convention
used by "rebase -i" that was rewritten in C, tying the loose end
between two GSoC topics that stomped on each other's toes.

* js/rebase-in-c-5.5-work-with-rebase-i-in-c:
  builtin rebase: prepare for builtin rebase -i

Rewrite "git rebase" in C.

* pk/rebase-in-c-5-test:
  builtin rebase: error out on incompatible option/mode combinations
  builtin rebase: use no-op editor when interactive is "implied"
  builtin rebase: show progress when connected to a terminal
  builtin rebase: fast-forward to onto if it is a proper descendant
  builtin rebase: optionally pass custom reflogs to reset_head()
  builtin rebase: optionally auto-detect the upstream

Rewrite "git rebase" in C.

* pk/rebase-in-c-4-opts:
  builtin rebase: support --root
  builtin rebase: add support for custom merge strategies
  builtin rebase: support `fork-point` option
  merge-base --fork-point: extract libified function
  builtin rebase: support --rebase-merges[=[no-]rebase-cousins]
  builtin rebase: support `--allow-empty-message` option
  builtin rebase: support `--exec`
  builtin rebase: support `--autostash` option
  builtin rebase: support `-C` and `--whitespace=<type>`
  builtin rebase: support `--gpg-sign` option
  builtin rebase: support `--autosquash`
  builtin rebase: support `keep-empty` option
  builtin rebase: support `ignore-date` option
  builtin rebase: support `ignore-whitespace` option
  builtin rebase: support --committer-date-is-author-date
  builtin rebase: support --rerere-autoupdate
  builtin rebase: support --signoff
  builtin rebase: allow selecting the rebase "backend"

Rewrite "git rebase" in C.

* pk/rebase-in-c-3-acts:
  builtin rebase: stop if `git am` is in progress
  builtin rebase: actions require a rebase in progress
  builtin rebase: support --edit-todo and --show-current-patch
  builtin rebase: support --quit
  builtin rebase: support --abort
  builtin rebase: support --skip
  builtin rebase: support --continue

Rewrite "git rebase" in C.

* pk/rebase-in-c-2-basic:
  builtin rebase: support `git rebase <upstream> <switch-to>`
  builtin rebase: only store fully-qualified refs in `options.head_name`
  builtin rebase: start a new rebase only if none is in progress
  builtin rebase: support --force-rebase
  builtin rebase: try to fast forward when possible
  builtin rebase: require a clean worktree
  builtin rebase: support the `verbose` and `diffstat` options
  builtin rebase: support --quiet
  builtin rebase: handle the pre-rebase hook and --no-verify
  builtin rebase: support `git rebase --onto A...B`
  builtin rebase: support --onto

Rewrite of the remaining "rebase -i" machinery in C.

* ag/rebase-i-in-c:
  rebase -i: move rebase--helper modes to rebase--interactive
  rebase -i: remove git-rebase--interactive.sh
  rebase--interactive2: rewrite the submodes of interactive rebase in C
  rebase -i: implement the main part of interactive rebase as a builtin
  rebase -i: rewrite init_basic_state() in C
  rebase -i: rewrite write_basic_state() in C
  rebase -i: rewrite the rest of init_revisions_and_shortrevisions() in C
  rebase -i: implement the logic to initialize $revisions in C
  rebase -i: remove unused modes and functions
  rebase -i: rewrite complete_action() in C
  t3404: todo list with commented-out commands only aborts
  sequencer: change the way skip_unnecessary_picks() returns its result
  sequencer: refactor append_todo_help() to write its message to a buffer
  rebase -i: rewrite checkout_onto() in C
  rebase -i: rewrite setup_reflog_action() in C
  sequencer: add a new function to silence a command, except if it fails
  rebase -i: rewrite the edit-todo functionality in C
  editor: add a function to launch the sequence editor
  rebase -i: rewrite append_todo_help() in C
  sequencer: make three functions and an enum from sequencer.c public

Rewrite of the "rebase" machinery in C.

* pk/rebase-in-c:
  builtin/rebase: support running "git rebase <upstream>"
  rebase: refactor common shell functions into their own file
  rebase: start implementing it as a builtin

Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Code clean-up that results in a small bugfix.

* jk/uploadpack-packobjectshook-fix:
  upload-pack: fix broken if/else chain in config callback

Belated documentation update to adjust to a new world order that
happened a yew years ago.

* uk/merge-subtree-doc-update:
  howto/using-merge-subtree: mention --allow-unrelated-histories

Code tightening.

* cb/compat-mmap-is-private-read-only:
  compat: make sure git_mmap is not expected to write

"git mergetool" learned to take the "--[no-]gui" option, just like
"git difftool" does.

* dl/mergetool-gui-option:
  doc: document diff/merge.guitool config keys
  completion: support `git mergetool --[no-]gui`
  mergetool: accept -g/--[no-]gui as arguments

The way DLLs are loaded on the Windows port has been improved.

* js/mingw-load-sys-dll:
  mingw: load system libraries the recommended way

The way the Windows port figures out the current directory has been
improved.

* js/mingw-getcwd:
  mingw: fix getcwd when the parent directory cannot be queried
  mingw: ensure `getcwd()` reports the correct case

Build fix.

* cb/khash-maybe-unused-function:
  khash: silence -Wunused-function for delta-islands
  commit-slabs: move MAYBE_UNUSED out

Code cleanup.

* jc/cocci-preincr:
  fsck: s/++i > 1/i++/
  cocci: simplify "if (++u > 1)" to "if (u++)"

Reorganize some tests and rename them; "ls t/" now gives a better
overview of what is tested for these scripts than before.

* ss/rename-tests:
  t7501: rename commit test to comply with naming convention
  t7500: rename commit tests script to comply with naming convention
  t7502: rename commit test script to comply with naming convention
  t7509: cleanup description and filename
  t2000: rename and combine checkout clash tests

Doc updates.

* ah/doc-updates:
  doc: fix formatting in git-update-ref
  doc: fix indentation of listing blocks in gitweb.conf.txt
  doc: fix descripion for 'git tag --format'
  doc: fix inappropriate monospace formatting
  doc: fix ASCII art tab spacing
  doc: clarify boundaries of 'git worktree list --porcelain'

Trivial bugfix.

* ds/reachable:
  commit-reach: fix cast in compare_commits_by_gen()

The receive.denyCurrentBranch=updateInstead codepath kicked in even
when the push should have been rejected due to other reasons, such
as it does not fast-forward or the update-hook rejects it, which
has been corrected.

* jc/receive-deny-current-branch-fix:
  receive: denyCurrentBranch=updateinstead should not blindly update

One of our CI tests to run with "unusual/experimental/random"
settings now also uses commit-graph and midx.

* ds/ci-commit-graph-and-midx:
  ci: add optional test variables

Developer support.

* jk/unused-function:
  config.mak.dev: enable -Wunused-function

Code clean-up.

* cb/remove-dead-init:
  multi-pack-index: avoid dead store for struct progress
  unpack-trees: avoid dead store for struct progress

Under certain circumstances, "git diff D:/a/b/c D:/a/b/d" on
Windows would strip initial parts from the paths because they
were not recognized as absolute, which has been corrected.

* js/diff-notice-has-drive-prefix:
  diff: don't attempt to strip prefix from absolute Windows paths

Plugging a handful of memory leaks in the ref-filter codepath.

* ot/ref-filter-plug-leaks:
  ref-filter: free item->value and item->value->s
  ls-remote: release memory instead of UNLEAK
  ref-filter: free memory from used_atom

Correct performance regression in commit ancestry computation when
generation numbers are involved.

* ds/reachable-first-parent-fix:
  commit-reach: fix first-parent heuristic

Code clean-up.

* rj/header-guards:
  headers: normalize the spelling of some header guards

Developer support.

* jk/test-tool-help:
  test-tool: show tool list on error

Docfix.

* sg/doc-show-branch-typofix:
  doc: fix small typo in git show-branch

Code clean-up.

* sb/submodule-helper-remove-cruft:
  builtin/submodule--helper: remove debugging leftover tracing

A mutex used in "git pack-objects" were not correctly initialized
and this caused "git repack" to dump core on Windows.

* js/pack-objects-mutex-init-fix:
  pack-objects (mingw): initialize `packing_data` mutex in the correct spot
  pack-objects (mingw): demonstrate a segmentation fault with large deltas
  pack-objects: fix typo 'detla' -> 'delta'

Code clean-up.

* tq/branch-style-fix:
  branch: trivial style fix

Code clean-up.

* tq/branch-create-wo-branch-get:
  builtin/branch.c: remove useless branch_get

More codepaths are moving away from hardcoded hash sizes.

* bc/hash-transition-part-15:
  rerere: convert to use the_hash_algo
  submodule: make zero-oid comparison hash function agnostic
  apply: rename new_sha1_prefix and old_sha1_prefix
  apply: replace hard-coded constants
  tag: express constant in terms of the_hash_algo
  transport: use parse_oid_hex instead of a constant
  upload-pack: express constants in terms of the_hash_algo
  refs/packed-backend: express constants using the_hash_algo
  packfile: express constants in terms of the_hash_algo
  pack-revindex: express constants in terms of the_hash_algo
  builtin/fetch-pack: remove constants with parse_oid_hex
  builtin/mktree: remove hard-coded constant
  builtin/repack: replace hard-coded constants
  pack-bitmap-write: use GIT_MAX_RAWSZ for allocation
  object_id.cocci: match only expressions of type 'struct object_id'

Code clean-up to serve as a BCP example.

* sb/strbuf-h-update:
  strbuf.h: format according to coding guidelines

The implementation of run_command() API on the UNIX platforms had a
bug that caused a command not on $PATH to be found in the current
directory.

* jk/run-command-notdot:
  run-command: mark path lookup errors with ENOENT

Test fix.

* tb/filter-alternate-refs:
  t5410: use longer path for sample script
  Documentation/config.txt: fix typo in core.alternateRefsCommand

"git send-email" learned to grab address-looking string on any
trailer whose name ends with "-by"; --suppress-cc=misc-by on the
command line, or setting sendemail.suppresscc configuration
variable to "misc-by", can be used to disable this behaviour.

This is a backward-incompatible change that may surprise existing
users.

* rv/send-email-cc-misc-by:
  send-email: also pick up cc addresses from -by trailers
  send-email: only consider lines containing @ or <> for automatic Cc'ing
  Documentation/git-send-email.txt: style fixes

"git range-diff" did not work well when the compared ranges had
changes in submodules and the "--submodule=log" was used.

* lm/range-diff-submodule-fix:
  range-diff: allow to diff files regardless of submodule config