Code cleanup.

* cb/notes-freeing-always-null-fix:
  builtin/notes: remove unnecessary free

Bugfix for the recently graduated "git rebase --rebase-merges".

* js/rebase-r-and-merge-head:
  status: rebase and merge can be in progress at the same time
  built-in rebase --skip/--abort: clean up stale .git/<name> files
  rebase -i: include MERGE_HEAD into files to clean up
  rebase -r: do not write MERGE_HEAD unless needed
  rebase -r: demonstrate bug with conflicting merges

When editing a patch in a "git add -i" session, a hunk could be
made to no-op.  The "git apply" program used to reject a patch with
such a no-op hunk to catch user mistakes, but it is now updated to
explicitly allow a no-op hunk in an edited patch.

* js/apply-recount-allow-noop:
  apply --recount: allow "no-op hunks"

"rev-parse --exclude=<pattern> --branches=<pattern>" etc. did not
quite work, which has been corrected.

* ra/rev-parse-exclude-glob:
  refs: fix some exclude patterns being ignored
  refs: show --exclude failure with --branches/tags/remotes=glob

Code clean-up with correction to make the reimplemented "git
rebase" a more faithful rewrite of the original, which also regains
performance.

* js/builtin-rebase-perf-fix:
  built-in rebase: reinstate `checkout -q` behavior where appropriate
  rebase: prepare reset_head() for more flags
  rebase: consolidate clean-up code before leaving reset_head()

Update the mailmap to unify multiple entries for the authors with
commits since v2.10.

* js/mailmap:
  Update .mailmap

"git rebase --autostash" did not correctly re-attach the HEAD at times.

* js/rebase-autostash-detach-fix:
  built-in rebase --autostash: leave the current branch alone if possible
  built-in rebase: demonstrate regression with --autostash

The "--no-patch" option, which can be used to get a high-level
overview without the actual line-by-line patch difference shown, of
the "range-diff" command was earlier broken, which has been
corrected.

* ab/range-diff-no-patch:
  range-diff: make diff option behavior (e.g. --stat) consistent
  range-diff: fix regression in passing along diff options
  range-diff doc: add a section about output stability

"git merge" and "git pull" that merges into an unborn branch used
to completely ignore "--verify-signatures", which has been
corrected.

* jk/verify-sig-merge-into-void:
  pull: handle --verify-signatures for unborn branch
  merge: handle --verify-signatures for unborn branch
  merge: extract verify_merge_signature() helper

Windows build update.

* js/mingw-res-rebuild:
  Windows: force-recompile git.res for differing architectures

Various functions have been audited for "-Wunused-parameter" warnings
and bugs in them got fixed.

* jk/unused-parameter-fixes:
  midx: double-check large object write loop
  assert NOARG/NONEG behavior of parse-options callbacks
  parse-options: drop OPT_DATE()
  apply: return -1 from option callback instead of calling exit(1)
  cat-file: report an error on multiple --batch options
  tag: mark "--message" option with NONEG
  show-branch: mark --reflog option as NONEG
  format-patch: mark "--no-numbered" option with NONEG
  status: mark --find-renames option with NONEG
  cat-file: mark batch options with NONEG
  pack-objects: mark index-version option as NONEG
  ls-files: mark exclude options as NONEG
  am: handle --no-patch-format option
  apply: mark include/exclude options as NONEG

The way -lcurl library gets linked has been simplified by taking
advantage of the fact that we can just ask curl-config command how.

* jk/curl-ldflags:
  build: link with curl-defined linker flags

Add a few tests for a topic already in 'master'.

* mg/gpg-fingerprint-test:
  t/t7510-signed-commit.sh: add signing subkey to Eris Discordia key
  t/t7510-signed-commit.sh: Add %GP to custom format checks

The codebase has been cleaned up to reduce "#ifndef NO_PTHREADS".

* nd/pthreads:
  Clean up pthread_create() error handling
  read-cache.c: initialize copy_len to shut up gcc 8
  read-cache.c: reduce branching based on HAVE_THREADS
  read-cache.c: remove #ifdef NO_PTHREADS
  pack-objects: remove #ifdef NO_PTHREADS
  preload-index.c: remove #ifdef NO_PTHREADS
  grep: clean up num_threads handling
  grep: remove #ifdef NO_PTHREADS
  attr.c: remove #ifdef NO_PTHREADS
  name-hash.c: remove #ifdef NO_PTHREADS
  index-pack: remove #ifdef NO_PTHREADS
  send-pack.c: move async's #ifdef NO_PTHREADS back to run-command.c
  run-command.h: include thread-utils.h instead of pthread.h
  thread-utils: macros to unconditionally compile pthreads API

The revision walker machinery learned to take advantage of the
commit generation numbers stored in the commit-graph file.

* ds/reachable-topo-order:
  t6012: make rev-list tests more interesting
  revision.c: generation-based topo-order algorithm
  commit/revisions: bookkeeping before refactoring
  revision.c: begin refactoring --topo-order logic
  test-reach: add rev-list tests
  test-reach: add run_three_modes method
  prio-queue: add 'peek' operation

Make the behavior when diff options (e.g. "--stat") are passed
consistent with how "diff" behaves.

Before 73a834e9 ("range-diff: relieve callers of low-level
configuration burden", 2018-07-22) running range-diff with "--stat"
would produce stat output and the diff output, as opposed to how
"diff" behaves where once "--stat" is specified "--patch" also needs
to be provided to emit the patch output.

As noted in a previous change ("range-diff doc: add a section about
output stability", 2018-11-07) the "--stat" output with "range-diff"
is useless at the moment.

But we should behave consistently with "diff" in anticipation of such
output being useful in the future, because it would make for confusing
UI if "diff" and "range-diff" behaved differently when it came to how
they interpret diff options.

The new behavior is also consistent with the existing documentation
added in ba931edd ("range-diff: populate the man page",
2018-08-13). See "[...]also accepts the regular diff options[...]" in
git-range-diff(1).
Signed-off-by: NÆvar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

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

The support for format-patch (and send-email) by the command-line
completion script (in contrib/) has been simplified a bit.

* nd/complete-format-patch:
  completion: use __gitcomp_builtin for format-patch

Pathspec matching against a tree object were buggy when negative
pathspec elements were involved, which has been fixed.

* nd/tree-walk-path-exclusion:
  tree-walk.c: fix overoptimistic inclusion in :(exclude) matching

The procedure to install dependencies before testing at Travis CI
is getting revamped for both simplicity and flexibility, taking
advantage of the recent move to the vm-based environment.

* sg/travis-install-dependencies:
  travis-ci: install packages in 'ci/install-dependencies.sh'

"git add" needs to internally run "diff-files" equivalent, and the
codepath learned the same optimization as "diff-files" has to run
lstat(2) in parallel to find which paths have been updated in the
working tree.

* bp/add-diff-files-optim:
  add: speed up cmd_add() by utilizing read_cache_preload()

The interface into "xdiff" library used to discover the offset and
size of a generated patch hunk by first formatting it into the
textual hunk header "@@ -n,m +k,l @@" and then parsing the numbers
out.  A new interface has been introduced to allow callers a more
direct access to them.

* jk/xdiff-interface:
  xdiff-interface: drop parse_hunk_header()
  range-diff: use a hunk callback
  diff: convert --check to use a hunk callback
  combine-diff: use an xdiff hunk callback
  diff: use hunk callback for word-diff
  diff: discard hunk headers for patch-ids earlier
  diff: avoid generating unused hunk header lines
  xdiff-interface: provide a separate consume callback for hunks
  xdiff: provide a separate emit callback for hunks

Assorted fixes for bugs found while auditing -Wunused-parameter
warnings.

* jk/misc-unused-fixes:
  approxidate: fix NULL dereference in date_time()
  pathspec: handle non-terminated strings with :(attr)
  approxidate: handle pending number for "specials"
  rev-list: handle flags for --indexed-objects

The code to traverse objects for reachability, used to decide what
objects are unreferenced and expendable, have been taught to also
consider per-worktree refs of other worktrees as starting points to
prevent data loss.

* nd/per-worktree-ref-iteration:
  git-worktree.txt: correct linkgit command name
  reflog expire: cover reflog from all worktrees
  fsck: check HEAD and reflog from other worktrees
  fsck: move fsck_head_link() to get_default_heads() to avoid some globals
  revision.c: better error reporting on ref from different worktrees
  revision.c: correct a parameter name
  refs: new ref types to make per-worktree refs visible to all worktrees
  Add a place for (not) sharing stuff between worktrees
  refs.c: indent with tabs, not spaces

The helper function to refresh the cached stat information in the
in-core index has learned to perform the lstat() part of the
operation in parallel on multi-core platforms.

* bp/refresh-index-using-preload:
  refresh_index: remove unnecessary calls to preload_index()
  speed up refresh_index() by utilizing preload_index()

Code clean-up for a topic already in 'master'.

* ag/rebase-i-in-c:
  sequencer.c: remove a stray semicolon

"git send-email --transfer-encoding=..." in recent versions of Git
sometimes produced an empty "Content-Transfer-Encoding:" header,
which has been corrected.

* al/send-email-auto-cte-fixup:
  send-email: avoid empty transfer encoding header

The history traversal used to implement the tag-following has been
optimized by introducing a new helper.

* ds/add-missing-tags:
  remote: make add_missing_tags() linear
  test-reach: test get_reachable_subset
  commit-reach: implement get_reachable_subset

Windows fix.

* sh/mingw-safer-compat-poll:
  poll: use GetTickCount64() to avoid wrap-around issues

In preparation to the day when we can deprecate and remove the
"rebase -p", make sure we can skip and later remove tests for
it.

* js/rebase-p-tests:
  tests: optionally skip `git rebase -p` tests
  t3418: decouple test cases from a previous `rebase -p` test case
  t3404: decouple some test cases from outcomes of previous test cases

Unify code to read the author-script used in "git am" and the
commands that use the sequencer machinery, e.g. "git rebase -i".

* pw/am-rebase-read-author-script:
  sequencer: use read_author_script()
  add read_author_script() to libgit
  am: rename read_author_script()
  am: improve author-script error reporting
  am: don't die in read_author_script()

Replace three string-list instances used as look-up tables in "git
fetch" with hashmaps.

* jc/war-on-string-list:
  fetch: replace string-list used as a look-up table with a hashmap

"git rev-parse --exclude=* --branches --branches"  (i.e. first
saying "add only things that do not match '*' out of all branches"
and then adding all branches, without any exclusion this time")
worked as expected, but "--exclude=* --all --all" did not work the
same way, which has been fixed.

* ag/rev-parse-all-exclude-fix:
  rev-parse: clear --exclude list after 'git rev-parse --all'

"git fetch" was a bit loose in parsing resposes from the other side
when talking over the protocol v2.

* jt/tighten-fetch-proto-v2-response:
  fetch-pack: be more precise in parsing v2 response

The submodule support has been updated to read from the blob at
HEAD:.gitmodules when the .gitmodules file is missing from the
working tree.

* ao/submodule-wo-gitmodules-checked-out:
  t/helper: add test-submodule-nested-repo-config
  submodule: support reading .gitmodules when it's not in the working tree
  submodule: add a helper to check if it is safe to write to .gitmodules
  t7506: clean up .gitmodules properly before setting up new scenario
  submodule: use the 'submodule--helper config' command
  submodule--helper: add a new 'config' subcommand
  t7411: be nicer to future tests and really clean things up
  t7411: merge tests 5 and 6
  submodule: factor out a config_set_in_gitmodules_file_gently function
  submodule: add a print_config_from_gitmodules() helper

Code readability fix.

* nb/worktree-api-doc:
  worktree: rename is_worktree_locked to worktree_lock_reason
  worktree: update documentation for lock_reason and lock_reason_valid

Code readability fix.

* ma/sequencer-do-reset-saner-loop-termination:
  sequencer: break out of loop explicitly

Windows fix.

* js/mingw-utf8-env:
  mingw: reencode environment variables on the fly (UTF-16 <-> UTF-8)
  t7800: fix quoting

Windows fix.

* js/mingw-perl5lib:
  mingw: unset PERL5LIB by default
  config: move Windows-specific config settings into compat/mingw.c
  config: allow for platform-specific core.* config settings
  config: rename `dummy` parameter to `cb` in git_default_config()

Windows fix.

* js/mingw-isatty-and-dup2:
  mingw: fix isatty() after dup2()