Code clean-up.

* jk/untracked-cache-more-fixes:
  untracked-cache: simplify parsing by dropping "len"
  untracked-cache: simplify parsing by dropping "next"
  untracked-cache: be defensive about missing NULs in index

A follow-up test for an earlier "git prune" improvements.

* jk/prune-optim:
  t5304: add a test for pruning with bitmaps

"make check-docs", "git help -a", etc. did not account for cases
where a particular build may deliberately omit some subcommands,
which has been corrected.

* js/misc-doc-fixes:
  Turn `git serve` into a test helper
  test-tool: handle the `-C <directory>` option just like `git`
  check-docs: do not bother checking for legacy scripts' documentation
  docs: exclude documentation for commands that have been excluded
  check-docs: allow command-list.txt to contain excluded commands
  help -a: do not list commands that are excluded from the build
  Makefile: drop the NO_INSTALL variable
  remote-testgit: move it into the support directory for t5801

%(push:track) token used in the --format option to "git
for-each-ref" and friends was not showing the right branch, which
has been fixed.

* dr/ref-filter-push-track-fix:
  ref-filter: use correct branch for %(push:track)

An earlier update for MinGW and Cygwin accidentally broke MSVC build,
which has been fixed.

* ss/msvc-path-utils-fix:
  MSVC: include compat/win32/path-utils.h for MSVC, too, for real_path()

"git clone" learned a new --server-option option when talking over
the protocol version 2.

* jt/clone-server-option:
  clone: send server options when using protocol v2
  transport: die if server options are unsupported

Code tightening against a "wrong" object appearing where an object
of a different type is expected, instead of blindly assuming that
the connection between objects are correctly made.

* tb/unexpected:
  rev-list: detect broken root trees
  rev-list: let traversal die when --missing is not in use
  get_commit_tree(): return NULL for broken tree
  list-objects.c: handle unexpected non-tree entries
  list-objects.c: handle unexpected non-blob entries
  t: introduce tests for unexpected object types
  t: move 'hex2oct' into test-lib-functions.sh

Further code clean-up to allow the lowest level of name-to-object
mapping layer to work with a passed-in repository other than the
default one.

* nd/sha1-name-c-wo-the-repository: (34 commits)
  sha1-name.c: remove the_repo from get_oid_mb()
  sha1-name.c: remove the_repo from other get_oid_*
  sha1-name.c: remove the_repo from maybe_die_on_misspelt_object_name
  submodule-config.c: use repo_get_oid for reading .gitmodules
  sha1-name.c: add repo_get_oid()
  sha1-name.c: remove the_repo from get_oid_with_context_1()
  sha1-name.c: remove the_repo from resolve_relative_path()
  sha1-name.c: remove the_repo from diagnose_invalid_index_path()
  sha1-name.c: remove the_repo from handle_one_ref()
  sha1-name.c: remove the_repo from get_oid_1()
  sha1-name.c: remove the_repo from get_oid_basic()
  sha1-name.c: remove the_repo from get_describe_name()
  sha1-name.c: remove the_repo from get_oid_oneline()
  sha1-name.c: add repo_interpret_branch_name()
  sha1-name.c: remove the_repo from interpret_branch_mark()
  sha1-name.c: remove the_repo from interpret_nth_prior_checkout()
  sha1-name.c: remove the_repo from get_short_oid()
  sha1-name.c: add repo_for_each_abbrev()
  sha1-name.c: store and use repo in struct disambiguate_state
  sha1-name.c: add repo_find_unique_abbrev_r()
  ...

When given a tag that points at a commit-ish, "git replace --graft"
failed to peel the tag before writing a replace ref, which did not
make sense because the old graft mechanism the feature wants to
mimick only allowed to replace one commit object with another.
This has been fixed.

* cc/replace-graft-peel-tags:
  replace: peel tag when passing a tag first to --graft
  replace: peel tag when passing a tag as parent to --graft
  t6050: redirect expected error output to a file
  t6050: use test_line_count instead of wc -l

The trace2 tracing facility learned to auto-generate a filename
when told to log to a directory.

* js/trace2-to-directory:
  trace2: write to directory targets

The list of conflicted paths shown in the editor while concluding a
conflicted merge was shown above the scissors line when the
clean-up mode is set to "scissors", even though it was commented
out just like the list of updated paths and other information to
help the user explain the merge better.

* dl/merge-cleanup-scissors-fix:
  cherry-pick/revert: add scissors line on merge conflict
  sequencer.c: save and restore cleanup mode
  merge: add scissors line on merge conflict
  merge: cleanup messages like commit
  parse-options.h: extract common --cleanup option
  commit: extract cleanup_mode functions to sequencer
  t7502: clean up style
  t7604: clean up style
  t3507: clean up style
  t7600: clean up style

"git cherry-pick" run with the "-x" or the "--signoff" option used
to (and more importantly, ought to) clean up the commit log message
with the --cleanup=space option by default, but this has been
broken since late 2017.  This has been fixed.

* pw/sequencer-cleanup-with-signoff-x-fix:
  sequencer: fix cleanup with --signoff and -x

The "git pack-objects" command learned to report the number of
objects it packed via the trace2 mechanism.

* jk/pack-objects-reports-num-objects-to-trace2:
  pack-objects: write objects packed to trace2

Doc formatting fix.

* tz/git-svn-doc-markup-fix:
  Documentation/git-svn: improve asciidoctor compatibility

Running "git add" on a repository created inside the current
repository is an explicit indication that the user wants to add it
as a submodule, but when the HEAD of the inner repository is on an
unborn branch, it cannot be added as a submodule.  Worse, the files
in its working tree can be added as if they are a part of the outer
repository, which is not what the user wants.  These problems are
being addressed.

* km/empty-repo-is-still-a-repo:
  add: error appropriately on repository with no commits
  dir: do not traverse repositories with no commits
  submodule: refuse to add repository with no commits

"git tag" learned to give an advice suggesting it might be a
mistake when creating an annotated or signed tag that points at
another tag.

* dl/warn-tagging-a-tag:
  tag: advise on nested tags
  tag: fix formatting

"git merge-recursive" backend recently learned a new heuristics to
infer file movement based on how other files in the same directory
moved.  As this is inherently less robust heuristics than the one
based on the content similarity of the file itself (rather than
based on what its neighbours are doing), it sometimes gives an
outcome unexpected by the end users.  This has been toned down to
leave the renamed paths in higher/conflicted stages in the index so
that the user can examine and confirm the result.

* en/merge-directory-renames:
  merge-recursive: switch directory rename detection default
  merge-recursive: give callers of handle_content_merge() access to contents
  merge-recursive: track information associated with directory renames
  t6043: fix copied test description to match its purpose
  merge-recursive: switch from (oid,mode) pairs to a diff_filespec
  merge-recursive: cleanup handle_rename_* function signatures
  merge-recursive: track branch where rename occurred in rename struct
  merge-recursive: remove ren[12]_other fields from rename_conflict_info
  merge-recursive: shrink rename_conflict_info
  merge-recursive: move some struct declarations together
  merge-recursive: use 'ci' for rename_conflict_info variable name
  merge-recursive: rename locals 'o' and 'a' to 'obuf' and 'abuf'
  merge-recursive: rename diff_filespec 'one' to 'o'
  merge-recursive: rename merge_options argument from 'o' to 'opt'
  Use 'unsigned short' for mode, like diff_filespec does

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

Build with gettext breaks on recent macOS w/ Homebrew when
/usr/local/bin is not on PATH, which has been corrected.

* js/macos-gettext-build:
  macOS: make sure that gettext is found

The recently added feature to add addresses that are on
anything-by: trailers in 'git send-email' was found to be way too
eager and considered nonsense strings as if they can be legitimate
beginning of *-by: trailer.  This has been tightened.

* bs/sendemail-tighten-anything-by:
  send-email: don't cc *-by lines with '-' prefix

"git send-email" has been taught to use quoted-printable when the
payload contains carriage-return.  The use of the mechanism is in
line with the design originally added the codepath that chooses QP
when the payload has overly long lines.

* bc/send-email-qp-cr:
  send-email: default to quoted-printable when CR is present

"git submodule foreach <command> --quiet" did not pass the option
down correctly, which has been corrected.

* nd/submodule-foreach-quiet:
  submodule foreach: fix "<command> --quiet" not being respected

Test fix on APFS that is incapable of store paths in Latin-1.

* js/iso8895-test-on-apfs:
  t9822: skip tests if file names cannot be ISO-8859-1 encoded

The GETTEXT_POISON test option has been quite broken ever since it
was made runtime-tunable, which has been fixed.

* jc/gettext-test-fix:
  gettext tests: export the restored GIT_TEST_GETTEXT_POISON

Code clean-up and a fix for "git fetch" by an explicit object name
(as opposed to fetching refs by name).

* jk/fetch-reachability-error-fix:
  fetch: do not consider peeled tags as advertised tips
  remote.c: make singular free_ref() public
  fetch: use free_refs()
  pkt-line: prepare buffer before handling ERR packets
  upload-pack: send ERR packet for non-tip objects
  t5530: check protocol response for "not our ref"
  t5516: drop ok=sigpipe from unreachable-want tests

The code is updated to check the result of memory allocation before
it is used in more places, by using xmalloc and/or xcalloc calls.

* jk/xmalloc:
  progress: use xmalloc/xcalloc
  xdiff: use xmalloc/xrealloc
  xdiff: use git-compat-util
  test-prio-queue: use xmalloc

A test update.

* km/t3000-retitle:
  t3000 (ls-files -o): widen description to reflect current tests

An underallocation in the code to read the untracked cache
extension has been corrected.

* js/untracked-cache-allocfix:
  untracked cache: fix off-by-one

Test fix.

* js/t3301-unbreak-notes-test:
  t3301: fix false negative

Doc formatting fix.

* tz/doc-apostrophe-no-longer-needed:
  Documentation/git-show-branch: avoid literal {apostrophe}

"git blame -- path" in a non-bare repository starts blaming from
the working tree, and the same command in a bare repository errors
out because there is no working tree by definition.  The command
has been taught to instead start blaming from the commit at HEAD,
which is more useful.

* sg/blame-in-bare-start-at-head:
  blame: default to HEAD in a bare repo when no start commit is given

Debugging code fix.

* tg/ls-files-debug-format-fix:
  ls-files: use correct format string

Docfix.

* po/describe-not-necessarily-7:
  describe doc: remove '7-char' abbreviation reference

Docfix.

* po/rerere-doc-fmt:
  rerere doc: quote `rerere.enabled`

Updating the display with progress message has been cleaned up to
deal better with overlong messages.

* sg/overlong-progress-fix:
  progress: break too long progress bar lines
  progress: clear previous progress update dynamically
  progress: assemble percentage and counters in a strbuf before printing
  progress: make display_progress() return void

While running "git diff" in a lazy clone, we can upfront know which
missing blobs we will need, instead of waiting for the on-demand
machinery to discover them one by one.  Aim to achieve better
performance by batching the request for these promised blobs.

* jt/batch-fetch-blobs-in-diff:
  diff: batch fetching of missing blobs
  sha1-file: support OBJECT_INFO_FOR_PREFETCH

Update docs around "gc".

* ab/gc-docs:
  gc docs: remove incorrect reference to gc.auto=0
  gc docs: clarify that "gc" doesn't throw away referenced objects
  gc docs: note "gc --aggressive" in "fast-import"
  gc docs: downplay the usefulness of --aggressive
  gc docs: note how --aggressive impacts --window & --depth
  gc docs: fix formatting for "gc.writeCommitGraph"
  gc docs: re-flow the "gc.*" section in "config"
  gc docs: include the "gc.*" section from "config" in "gc"
  gc docs: clean grammar for "gc.bigPackThreshold"
  gc docs: stop noting "repack" flags
  gc docs: modernize the advice for manually running "gc"

"git submodule" learns "set-branch" subcommand that allows the
submodule.*.branch settings to be modified.

* dl/submodule-set-branch:
  submodule: teach set-branch subcommand
  submodule--helper: teach config subcommand --unset
  git-submodule.txt: "--branch <branch>" option defaults to 'master'

Performance fix for "rev-list --parents -- pathspec".

* jk/revision-rewritten-parents-in-prio-queue:
  revision: use a prio_queue to hold rewritten parents

Performance fix around "git blame", especially in a linear history
(which is the norm we should optimize for).

* dk/blame-keep-origin-blob:
  blame.c: don't drop origin blobs as eagerly