When cloning with "--recursive", we'd generally expect
submodules to show progress reports if the main clone did,
too.

In older versions of git, this mostly worked out of the
box. Since we show progress by default when stderr is a tty,
and since the child clones inherit the parent stderr, then
both processes would come to the same decision by default.
If the parent clone was asked for "--quiet", we passed down
"--quiet" to the child. However, if stderr was not a tty and
the user specified "--progress", we did not propagate this
to the child.

That's a minor bug, but things got much worse when we
switched recently to submodule--helper's update_clone
command. With that change, the stderr of the child clones
are always connected to a pipe, and we never output
progress at all.

This patch teaches git-submodule and git-submodule--helper
how to pass down an explicit "--progress" flag when cloning.
The clone command then decides to propagate that flag based
on the cloning decision made earlier (which takes into
account isatty(2) of the parent process, existing --progress
or --quiet flags, etc). Since the child processes always run
without a tty on stderr, we don't have to worry about
passing an explicit "--no-progress"; it's the default for
them.

This fixes the recent loss of progress during recursive
clones. And as a bonus, it makes:

  git clone --recursive --progress ... 2>&1 | cat

work by triggering progress explicitly in the children.

Signed-off-by: Jeff King <peff@peff.net>
Acked-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

"git clone --resurse-submodules --reference $path $URL" is a way to
reduce network transfer cost by borrowing objects in an existing
$path repository when cloning the superproject from $URL; it
learned to also peek into $path for presense of corresponding
repositories of submodules and borrow objects from there when able.

* sb/submodule-clone-rr:
  clone: recursive and reference option triggers submodule alternates
  clone: implement optional references
  clone: clarify option_reference as required
  clone: factor out checking for an alternate path
  submodule--helper update-clone: allow multiple references
  submodule--helper module-clone: allow multiple references
  t7408: merge short tests, factor out testing method
  t7408: modernize style

Enhance "git status --porcelain" output by collecting more data on
the state of the index and the working tree files, which may
further be used to teach git-prompt (in contrib/) to make fewer
calls to git.

* jh/status-v2-porcelain:
  status: unit tests for --porcelain=v2
  test-lib-functions.sh: add lf_to_nul helper
  git-status.txt: describe --porcelain=v2 format
  status: print branch info with --porcelain=v2 --branch
  status: print per-file porcelain v2 status data
  status: collect per-file data for --porcelain=v2
  status: support --porcelain[=<version>]
  status: cleanup API to wt_status_print
  status: rename long-format print routines

Clarify various ways to specify the "revision ranges" in the
documentation.

* po/range-doc:
  doc: revisions: sort examples and fix alignment of the unchanged
  doc: revisions: show revision expansion in examples
  doc: revisions - clarify reachability examples
  doc: revisions - define `reachable`
  doc: gitrevisions - clarify 'latter case' is revision walk
  doc: gitrevisions - use 'reachable' in page description
  doc: revisions: single vs multi-parent notation comparison
  doc: revisions: extra clarification of <rev>^! notation effects
  doc: revisions: give headings for the two and three dot notations
  doc: show the actual left, right, and boundary marks
  doc: revisions - name the left and right sides
  doc: use 'symmetric difference' consistently

"git nosuchcommand --help" said "No manual entry for gitnosuchcommand",
which was not intuitive, given that "git nosuchcommand" said "git:
'nosuchcommand' is not a git command".

* rt/help-unknown:
  help: make option --help open man pages only for Git commands
  help: introduce option --exclude-guides

An incoming "git push" that attempts to push too many bytes can now
be rejected by setting a new configuration variable at the receiving
end.

* cc/receive-pack-limit:
  receive-pack: allow a maximum input size to be specified
  unpack-objects: add --max-input-size=<size> option
  index-pack: add --max-input-size=<size> option

"git format-patch --cover-letter HEAD^" to format a single patch
with a separate cover letter now numbers the output as [PATCH 0/1]
and [PATCH 1/1] by default.

* jk/format-patch-number-singleton-patch-with-cover:
  format-patch: show 0/1 and 1/1 for singleton patch with cover letter

The delta-base-cache mechanism has been a key to the performance in
a repository with a tightly packed packfile, but it did not scale
well even with a larger value of core.deltaBaseCacheLimit.

* jk/delta-base-cache:
  t/perf: add basic perf tests for delta base cache
  delta_base_cache: use hashmap.h
  delta_base_cache: drop special treatment of blobs
  delta_base_cache: use list.h for LRU
  release_delta_base_cache: reuse existing detach function
  clear_delta_base_cache_entry: use a more descriptive name
  cache_or_unpack_entry: drop keep_cache parameter

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

l10n-2.10.0-rnd2.2

* tag 'l10n-2.10.0-rnd2.2' of git://github.com/git-l10n/git-po:
  l10n: Updated Vietnamese translation for v2.10.0-rc2 (2757t)