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

Our HTTP client code used to advertise that we accept gzip encoding
from the other side; instead, just let cURL library to advertise
and negotiate the best one.

* bw/remote-curl-compressed-responses:
  remote-curl: accept compressed responses with protocol v2
  remote-curl: accept all encodings supported by curl

Leak plugging.

* ma/unpack-trees-free-msgs:
  unpack_trees_options: free messages when done
  argv-array: return the pushed string from argv_push*()
  merge-recursive: provide pair of `unpack_trees_{start,finish}()`
  merge: setup `opts` later in `checkout_fast_forward()`

Many tests hardcode the raw object names, which would change once
we migrate away from SHA-1.  While some of them must test against
exact object names, most of them do not have to use hardcoded
constants in the test.  The latter kind of tests have been updated
to test the moral equivalent of the original without hardcoding the
actual object names.

* bc/hash-independent-tests: (28 commits)
  t5300: abstract away SHA-1-specific constants
  t4208: abstract away SHA-1-specific constants
  t4045: abstract away SHA-1-specific constants
  t4042: abstract away SHA-1-specific constants
  t4205: sort log output in a hash-independent way
  t/lib-diff-alternative: abstract away SHA-1-specific constants
  t4030: abstract away SHA-1-specific constants
  t4029: abstract away SHA-1-specific constants
  t4029: fix test indentation
  t4022: abstract away SHA-1-specific constants
  t4020: abstract away SHA-1-specific constants
  t4014: abstract away SHA-1-specific constants
  t4008: abstract away SHA-1-specific constants
  t4007: abstract away SHA-1-specific constants
  t3905: abstract away SHA-1-specific constants
  t3702: abstract away SHA-1-specific constants
  t3103: abstract away SHA-1-specific constants
  t2203: abstract away SHA-1-specific constants
  t: skip pack tests if not using SHA-1
  t4044: skip test if not using SHA-1
  ...

We used to call regfree() after regcomp() failed in some codepaths,
which have been corrected.

* ma/regex-no-regfree-after-comp-fail:
  regex: do not call `regfree()` if compilation fails

Leak plugging.

* ma/config-store-data-clear:
  config: let `config_store_data_clear()` handle `key`
  config: let `config_store_data_clear()` handle `value_regex`
  config: free resources of `struct config_store_data`

Avoid unchecked snprintf() to make future code auditing easier.

* jk/snprintf-truncation:
  fmt_with_err: add a comment that truncation is OK
  shorten_unambiguous_ref: use xsnprintf
  fsmonitor: use internal argv_array of struct child_process
  log_write_email_headers: use strbufs
  http: use strbufs instead of fixed buffers

Error codepath fix.

* jk/config-blob-sans-repo:
  config: die when --blob is used outside a repository

By code restructuring of submodule merge in merge-recursive,
informational messages from the codepath are now given using the
same mechanism as other output, and honor the merge.verbosity
configuration.  The code also learned to give a few new messages
when a submodule three-way merge resolves cleanly when one side
records a descendant of the commit chosen by the other side.

* sb/submodule-merge-in-merge-recursive:
  merge-recursive: give notice when submodule commit gets fast-forwarded
  merge-recursive: i18n submodule merge output and respect verbosity
  submodule.c: move submodule merging to merge-recursive.c

Error codepath fix.

* js/empty-config-section-fix:
  config: a user-provided invalid section is not a BUG

"git fetch $there $refspec" that talks over protocol v2 can take
advantage of server-side ref filtering; the code has been extended
so that this mechanism triggers also when fetching with configured
refspec.

* bw/ref-prefix-for-configured-refspec: (38 commits)
  fetch: generate ref-prefixes when using a configured refspec
  refspec: consolidate ref-prefix generation logic
  submodule: convert push_unpushed_submodules to take a struct refspec
  remote: convert check_push_refs to take a struct refspec
  remote: convert match_push_refs to take a struct refspec
  http-push: store refspecs in a struct refspec
  transport: remove transport_verify_remote_names
  send-pack: store refspecs in a struct refspec
  transport: convert transport_push to take a struct refspec
  push: convert to use struct refspec
  push: check for errors earlier
  remote: convert match_explicit_refs to take a struct refspec
  remote: convert get_ref_match to take a struct refspec
  remote: convert query_refspecs to take a struct refspec
  remote: convert apply_refspecs to take a struct refspec
  remote: convert get_stale_heads to take a struct refspec
  fetch: convert prune_refs to take a struct refspec
  fetch: convert get_ref_map to take a struct refspec
  fetch: convert do_fetch to take a struct refspec
  refspec: remove the deprecated functions
  ...

Error behaviour of "git grep" when it cannot read the index was
inconsistent with other commands that uses the index, which has
been corrected to error out early.

* sb/grep-die-on-unreadable-index:
  grep: handle corrupt index files early

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

"git submodule update" attempts two different kinds of "git fetch"
against the upstream repository to grab a commit bound at the
submodule's path, but it incorrectly gave up if the first kind
(i.e. a normal fetch) failed, making the second "last resort" one
(i.e. fetching an exact commit object by object name) ineffective.
This has been corrected.

* sb/submodule-update-try-harder:
  git-submodule.sh: try harder to fetch a submodule

Update credential-netrc helper (in contrib/) to allow customizing
the GPG used to decrypt the encrypted .netrc file.

* lm/credential-netrc:
  git-credential-netrc: accept gpg option
  git-credential-netrc: adapt to test framework for git

When a short hexadecimal string is used to name an object but there
are multiple objects that share the string as the prefix of their
names, the code lists these ambiguous candidates in a help message.
These object names are now sorted according to their types for
easier eyeballing.

* ab/get-short-oid:
  get_short_oid: sort ambiguous objects by type, then SHA-1
  sha1-name.c: move around the collect_ambiguous() function
  git-p4: change "commitish" typo to "committish"
  sha1-array.h: align function arguments
  sha1-name.c: remove stray newline

Transfer protocol v2 learned to support the partial clone.

* jt/partial-clone-proto-v2:
  {fetch,upload}-pack: support filter in protocol v2
  upload-pack: read config when serving protocol v2
  upload-pack: fix error message typo

Conversion from uchar[20] to struct object_id continues.

* bc/object-id: (42 commits)
  merge-one-file: compute empty blob object ID
  add--interactive: compute the empty tree value
  Update shell scripts to compute empty tree object ID
  sha1_file: only expose empty object constants through git_hash_algo
  dir: use the_hash_algo for empty blob object ID
  sequencer: use the_hash_algo for empty tree object ID
  cache-tree: use is_empty_tree_oid
  sha1_file: convert cached object code to struct object_id
  builtin/reset: convert use of EMPTY_TREE_SHA1_BIN
  builtin/receive-pack: convert one use of EMPTY_TREE_SHA1_HEX
  wt-status: convert two uses of EMPTY_TREE_SHA1_HEX
  submodule: convert several uses of EMPTY_TREE_SHA1_HEX
  sequencer: convert one use of EMPTY_TREE_SHA1_HEX
  merge: convert empty tree constant to the_hash_algo
  builtin/merge: switch tree functions to use object_id
  builtin/am: convert uses of EMPTY_TREE_SHA1_BIN to the_hash_algo
  sha1-file: add functions for hex empty tree and blob OIDs
  builtin/receive-pack: avoid hard-coded constants for push certs
  diff: specify abbreviation size in terms of the_hash_algo
  upload-pack: replace use of several hard-coded constants
  ...

"git blame" learns to unhighlight uninteresting metadata from the
originating commit on lines that are the same as the previous one,
and also paint lines in different colors depending on the age of
the commit.

* sb/blame-color:
  builtin/blame: add new coloring scheme config
  builtin/blame: highlight recently changed lines
  builtin/blame: dim uninteresting metadata lines

"git submodule update" and "git submodule add" supported the
"--reference" option to borrow objects from a neighbouring local
repository like "git clone" does, but lacked the more recent
invention "--dissociate".  Also "git submodule add" has been taught
to take the "--progress" option.

* cf/submodule-progress-dissociate:
  submodule: add --dissociate option to add/update commands
  submodule: add --progress option to add command
  submodule: clean up substitutions in script

Command line completion (in contrib/) learned to complete pathnames
for various commands better.

* sg/complete-paths:
  t9902-completion: exercise __git_complete_index_file() directly
  completion: don't return with error from __gitcomp_file_direct()
  completion: fill COMPREPLY directly when completing paths
  completion: improve handling quoted paths in 'git ls-files's output
  completion: remove repeated dirnames with 'awk' during path completion
  t9902-completion: ignore COMPREPLY element order in some tests
  completion: use 'awk' to strip trailing path components
  completion: let 'ls-files' and 'diff-index' filter matching paths
  completion: improve handling quoted paths on the command line
  completion: support completing non-ASCII pathnames
  completion: simplify prefix path component handling during path completion
  completion: move __git_complete_index_file() next to its helpers
  t9902-completion: add tests demonstrating issues with quoted pathnames

Developer support.  Use newer GCC on one of the builds done at
TravisCI.org to get more warnings and errors diagnosed.

* nd/travis-gcc-8:
  travis-ci: run gcc-8 on linux-gcc jobs

Memory optimization.

* nd/pack-struct-commit:
  commit.h: rearrange 'index' to shrink struct commit

"git update-ref A B" is supposed to ensure that ref A does not yet
exist when B is a NULL OID, but this check was not done correctly
for pseudo-refs outside refs/ hierarchy, e.g. MERGE_HEAD.

* ma/create-pseudoref-with-null-old-oid:
  refs: handle zero oid for pseudorefs
  t1400: add tests around adding/deleting pseudorefs
  refs.c: refer to "object ID", not "sha1", in error messages

Code clean-up to turn history traversal more robust in a
semi-corrupt repository.

* jk/unavailable-can-be-missing:
  mark_parents_uninteresting(): avoid most allocation
  mark_parents_uninteresting(): replace list with stack
  mark_parents_uninteresting(): drop missing object check
  mark_tree_contents_uninteresting(): drop missing object check

"git status" learned to honor a new status.renames configuration to
skip rename detection, which could be useful for those who want to
do so without disabling the default rename detection done by the
"git diff" command.

* bp/status-rename-config:
  add status config and command line options for rename detection

Developer support update, by using BUG() macro instead of die() to
mark codepaths that should not happen more clearly.

* js/use-bug-macro:
  BUG_exit_code: fix sparse "symbol not declared" warning
  Convert remaining die*(BUG) messages
  Replace all die("BUG: ...") calls by BUG() ones
  run-command: use BUG() to report bugs, not die()
  test-tool: help verifying BUG() code paths

Code clean-up to avoid non-standard-conformant pointer arithmetic.

* rs/no-null-ptr-arith-in-fast-export:
  fast-export: avoid NULL pointer arithmetic

the_repository->index is not a allocated piece of memory but
repo_clear() indiscriminately attempted to free(3) it, which has
been corrected.

* nd/repo-clear-keep-the-index:
  repository: fix free problem with repo_clear(the_repository)

Code clean-up to adjust to a more recent lockfile API convention that
allows lockfile instances kept on the stack.

* ma/lockfile-cleanup:
  lock_file: move static locks into functions
  lock_file: make function-local locks non-static
  refs.c: do not die if locking fails in `delete_pseudoref()`
  refs.c: do not die if locking fails in `write_pseudoref()`
  t/helper/test-write-cache: clean up lock-handling

Test cleanup.

* sg/t6500-no-redirect-of-stdin:
  t6050-replace: don't disable stdin for the whole test script

With merge.renames configuration set to false, the recursive merge
strategy can be told not to spend cycles trying to find renamed
paths and merge them accordingly.

* bp/merge-rename-config:
  merge: pass aggressive when rename detection is turned off
  merge: add merge.renames config setting
  merge: update documentation for {merge,diff}.renameLimit

The implementation of "git rebase -i --root" has been updated to use
the sequencer machinery more.

* js/sequencer-and-root-commits:
  rebase --rebase-merges: root commits can be cousins, too
  rebase --rebase-merges: a "merge" into a new root is a fast-forward
  sequencer: allow introducing new root commits
  rebase -i --root: let the sequencer handle even the initial part
  sequencer: learn about the special "fake root commit" handling
  sequencer: extract helper to update active_cache_tree

"git send-email" can sometimes offer confirmation dialog "Send this
email?" with choices 'Yes', 'No', 'Quit', and 'All'.  A new action
'Edit' has been added to this dialog's choice.

* dd/send-email-reedit:
  git-send-email: allow re-editing of message

* maint: (25 commits)
  Git 2.17.1
  Git 2.16.4
  Git 2.15.2
  Git 2.14.4
  Git 2.13.7
  fsck: complain when .gitmodules is a symlink
  index-pack: check .gitmodules files with --strict
  unpack-objects: call fsck_finish() after fscking objects
  fsck: call fsck_finish() after fscking objects
  fsck: check .gitmodules content
  fsck: handle promisor objects in .gitmodules check
  fsck: detect gitmodules files
  fsck: actually fsck blob data
  fsck: simplify ".git" check
  index-pack: make fsck error message more specific
  verify_path: disallow symlinks in .gitmodules
  update-index: stat updated files earlier
  verify_dotfile: mention case-insensitivity in comment
  verify_path: drop clever fallthrough
  skip_prefix: add case-insensitive variant
  ...

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

The command line completion mechanism (in contrib/) learned to load
custom completion file for "git $command" where $command is a
custom "git-$command" that the end user has on the $PATH when using
newer version of bash.

* fg/completion-external:
  completion: load completion file for external subcommand

Asciidoctor gives a reasonable imitation for AsciiDoc, but does not
render illustration in a literal block correctly when indented with
HT by default. The problem is fixed by forcing 8-space tabs.

* bc/asciidoctor-tab-width:
  Documentation: render revisions correctly under Asciidoctor
  Documentation: use 8-space tabs with Asciidoctor

Doc update.

* nd/pack-unreachable-objects-doc:
  pack-objects: validation and documentation about unreachable options

Typofix.

* nd/completion-aliasfiletype-typofix:
  completion: fix misspelled config key aliasesfiletype