Shell completion (in contrib/) updates.

* rt/completion-help:
  completion: add 'revisions' and 'everyday' to 'git help'
  completion: add option '--guides' to 'git help'

Minor code cleanup.

* ak/use-hashmap-iter-first-in-submodule-config:
  submodule-config: use hashmap_iter_first()

The repository set-up sequence has been streamlined (the biggest
change is that there is no longer git_config_early()), so that we
do not attempt to look into refs/* when we know we do not have a
Git repository.

* jk/check-repository-format:
  verify_repository_format: mark messages for translation
  setup: drop repository_format_version global
  setup: unify repository version callbacks
  init: use setup.c's repo version verification
  setup: refactor repo format reading and verification
  config: drop git_config_early
  check_repository_format_gently: stop using git_config_early
  lazily load core.sharedrepository
  wrap shared_repository global in get/set accessors
  setup: document check_repository_format()

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

Build updates for MSVC.

* ss/msvc:
  MSVC: use shipped headers instead of fallback definitions
  MSVC: vsnprintf in Visual Studio 2015 doesn't need SNPRINTF_SIZE_CORR any more

A minor documentation update.

* oa/doc-diff-check:
  Documentation: git diff --check detects conflict markers

Minor API documentation update.

* pb/opt-cmdmode-doc:
  api-parse-options.txt: document OPT_CMDMODE()

"git apply -v" learned to report paths in the patch that were
skipped via --include/--exclude mechanism or being outside the
current working directory.

* nd/apply-report-skip:
  apply: report patch skipping in verbose mode

A minor documentation update.

* nd/apply-doc:
  git-apply.txt: mention the behavior inside a subdir
  git-apply.txt: remove a space

"git merge" used to allow merging two branches that have no common
base by default, which led to a brand new history of an existing
project created and then get pulled by an unsuspecting maintainer,
which allowed an unnecessary parallel history merged into the
existing project.  The command has been taught not to allow this by
default, with an escape hatch "--allow-unrelated-histories" option
to be used in a rare event that merges histories of two projects
that started their lives independently.

* jc/merge-refuse-new-root:
  merge: refuse to create too cool a merge by default

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

"git tag" can create an annotated tag without explicitly given an
"-a" (or "-s") option (i.e. when a tag message is given).  A new
configuration variable, tag.forceSignAnnotated, can be used to tell
the command to create signed tag in such a situation.

* la/tag-force-signing-annotated-tags:
  tag: add the option to force signing of annotated tags

"git -c credential.<var>=<value> submodule" can now be used to
propagate configuration variables related to credential helper
down to the submodules.

* jk/submodule-c-credential:
  git_config_push_parameter: handle empty GIT_CONFIG_PARAMETERS
  git: submodule honor -c credential.* from command line
  quote: implement sq_quotef()
  submodule: fix segmentation fault in submodule--helper clone
  submodule: fix submodule--helper clone usage
  submodule: check argc count for git submodule--helper clone
  submodule: don't pass empty string arguments to submodule--helper clone

"git merge FETCH_HEAD" dereferenced NULL pointer when merging
nothing into an unborn history (which is arguably unusual usage,
which perhaps was the reason why nobody noticed it).

* jv/merge-nothing-into-void:
  merge: fix NULL pointer dereference when merging nothing into void

When "git merge --squash" stopped due to conflict, the concluding
"git commit" failed to read in the SQUASH_MSG that shows the log
messages from all the squashed commits.

* ss/commit-squash-msg:
  commit: do not lose SQUASH_MSG contents

"git rebase -x" can be used without passing "-i" option.

* sb/rebase-x:
  t3404: cleanup double empty lines between tests
  rebase: decouple --exec from --interactive

The tests that involve running httpd leaked the system-wide
configuration in /etc/gitconfig to the tested environment.

* jk/test-httpd-config-nosystem:
  t/lib-httpd: pass through GIT_CONFIG_NOSYSTEM env

"git send-email" had trouble parsing alias file in mailrc format
when lines in it had trailing whitespaces on them.

* jk/send-email-rtrim-mailrc-alias:
  send-email: ignore trailing whitespace in mailrc alias file

A code clarification.

* jk/credential-cache-comment-exit:
  credential-cache--daemon: clarify "exit" action semantics

Rename bunch of tests on "git clone" for better organization.

* sb/clone-t57-t56:
  clone tests: rename t57* => t56*

"git p4" now allows P4 author names to be mapped to Git author
names.

* ls/p4-map-user:
  git-p4: map a P4 user to Git author name and email address

A minor documentation update.

* cc/doc-recommend-performance-trace-to-file:
  Documentation: talk about pager in api-trace.txt

Code clean-up.

* pb/t7502-drop-dup:
  t/t7502 : drop duplicate test

"git mergetool" did not work well with conflicts that both sides
deleted.

* da/mergetool-delete-delete-conflict:
  mergetool: honor tempfile configuration when resolving delete conflicts
  mergetool: support delete/delete conflicts

A major part of "git submodule update" has been ported to C to take
advantage of the recently added framework to run download tasks in
parallel.

* sb/submodule-parallel-update:
  clone: allow an explicit argument for parallel submodule clones
  submodule update: expose parallelism to the user
  submodule helper: remove double 'fatal: ' prefix
  git submodule update: have a dedicated helper for cloning
  run_processes_parallel: rename parameters for the callbacks
  run_processes_parallel: treat output of children as byte array
  submodule update: direct error message to stderr
  fetching submodules: respect `submodule.fetchJobs` config option
  submodule-config: drop check against NULL
  submodule-config: keep update strategy around

The command line argument parser for "receive-pack" has been
rewritten to use parse-options.

* ss/receive-pack-parse-options:
  builtin/receive-pack.c: use parse_options API

Code clean-up.

* ss/exc-flag-is-a-collection-of-bits:
  dir: store EXC_FLAG_* values in unsigned integers

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

The startup_info data, which records if we are working inside a
repository (among other things), are now uniformly available to Git
subcommand implementations, and Git avoids attempting to touch
references when we are not in a repository.

* jk/startup-info:
  use setup_git_directory() in test-* programs
  grep: turn off gitlink detection for --no-index
  mailmap: do not resolve blobs in a non-repository
  remote: don't resolve HEAD in non-repository
  setup: set startup_info->have_repository more reliably
  setup: make startup_info available everywhere

A test for tags has been restructured so that more parts of it can
easily be run on a platform without a working GnuPG.

* es/test-gpg-tags:
  t6302: skip only signed tags rather than all tests when GPG is missing
  t6302: also test annotated in addition to signed tags
  t6302: normalize names and descriptions of signed tags
  lib-gpg: drop unnecessary "missing GPG" warning

strbuf_getwholeline() did not NUL-terminate the buffer on certain
corner cases in its error codepath.

* jk/getwholeline-getdelim-empty:
  strbuf_getwholeline: NUL-terminate getdelim buffer on error

A small memory leak in an error codepath has been plugged in xdiff
code.

* rj/xdiff-prepare-plug-leak-on-error-codepath:
  xdiff/xprepare: fix a memory leak
  xdiff/xprepare: use the XDF_DIFF_ALG() macro to access flag bits

Code clean-up.

* jc/index-pack:
  index-pack: add a helper function to derive .idx/.keep filename

Fetching of history by naming a commit object name directly didn't
work across remote-curl transport.

* gf/fetch-pack-direct-object-fetch:
  fetch-pack: update the documentation for "<refs>..." arguments
  fetch-pack: fix object_id of exact sha1

"git index-pack --keep[=<msg>] pack-$name.pack" simply did not work.

* jc/maint-index-pack-keep:
  index-pack: correct --keep[=<msg>]

* mm/lockfile-error-message:
  lockfile: improve error message when lockfile exists
  lockfile: mark strings for translation

The "--local-env-vars" and "--resolve-git-dir" options of "git
rev-parse" failed to work outside a repository when the command's
option parsing was rewritten in 1.8.5 era.

* jk/rev-parse-local-env-vars:
  rev-parse: let some options run outside repository
  t1515: add tests for rev-parse out-of-repo helpers

"git config --get-urlmatch", unlike other variants of the "git
config --get" family, did not signal error with its exit status
when there was no matching configuration.

* jk/config-get-urlmatch:
  Documentation/git-config: fix --get-all description
  Documentation/git-config: use bulleted list for exit codes
  config: fail if --get-urlmatch finds no value

* jk/add-i-highlight:
  add--interactive: allow custom diff highlighting programs