git: updated to 2.19.0

Git 2.19 Release Notes

Updates since v2.18
-------------------

UI, Workflows & Features

 * "git diff" compares the index and the working tree.  For paths
   added with intent-to-add bit, the command shows the full contents
   of them as added, but the paths themselves were not marked as new
   files.  They are now shown as new by default.

   "git apply" learned the "--intent-to-add" option so that an
   otherwise working-tree-only application of a patch will add new
   paths to the index marked with the "intent-to-add" bit.

 * "git grep" learned the "--column" option that gives not just the
   line number but the column number of the hit.

 * The "-l" option in "git branch -l" is an unfortunate short-hand for
   "--create-reflog", but many users, both old and new, somehow expect
   it to be something else, perhaps "--list".  This step warns when "-l"
   is used as a short-hand for "--create-reflog" and warns about the
   future repurposing of the it when it is used.

 * The userdiff pattern for .php has been updated.

 * The content-transfer-encoding of the message "git send-email" sends
   out by default was 8bit, which can cause trouble when there is an
   overlong line to bust RFC 5322/2822 limit.  A new option 'auto' to
   automatically switch to quoted-printable when there is such a line
   in the payload has been introduced and is made the default.

 * "git checkout" and "git worktree add" learned to honor
   checkout.defaultRemote when auto-vivifying a local branch out of a
   remote tracking branch in a repository with multiple remotes that
   have tracking branches that share the same names.
   (merge 8d7b558bae ab/checkout-default-remote later to maint).

 * "git grep" learned the "--only-matching" option.

 * "git rebase --rebase-merges" mode now handles octopus merges as
   well.

 * Add a server-side knob to skip commits in exponential/fibbonacci
   stride in an attempt to cover wider swath of history with a smaller
   number of iterations, potentially accepting a larger packfile
   transfer, instead of going back one commit a time during common
   ancestor discovery during the "git fetch" transaction.
   (merge 42cc7485a2 jt/fetch-negotiator-skipping later to maint).

 * A new configuration variable core.usereplacerefs has been added,
   primarily to help server installations that want to ignore the
   replace mechanism altogether.

 * Teach "git tag -s" etc. a few configuration variables (gpg.format
   that can be set to "openpgp" or "x509", and gpg.<format>.program
   that is used to specify what program to use to deal with the format)
   to allow x.509 certs with CMS via "gpgsm" to be used instead of
   openpgp via "gnupg".

 * Many more strings are prepared for l10n.

 * "git p4 submit" learns to ask its own pre-submit hook if it should
   continue with submitting.

 * The test performed at the receiving end of "git push" to prevent
   bad objects from entering repository can be customized via
   receive.fsck.* configuration variables; we now have gained a
   counterpart to do the same on the "git fetch" side, with
   fetch.fsck.* configuration variables.

 * "git pull --rebase=interactive" learned "i" as a short-hand for
   "interactive".

 * "git instaweb" has been adjusted to run better with newer Apache on
   RedHat based distros.

 * "git range-diff" is a reimplementation of "git tbdiff" that lets us
   compare individual patches in two iterations of a topic.

 * The sideband code learned to optionally paint selected keywords at
   the beginning of incoming lines on the receiving end.

 * "git branch --list" learned to take the default sort order from the
   'branch.sort' configuration variable, just like "git tag --list"
   pays attention to 'tag.sort'.

 * "git worktree" command learned "--quiet" option to make it less
   verbose.

Performance, Internal Implementation, Development Support etc.

 * The bulk of "git submodule foreach" has been rewritten in C.

 * The in-core "commit" object had an all-purpose "void *util" field,
   which was tricky to use especially in library-ish part of the
   code.  All of the existing uses of the field has been migrated to a
   more dedicated "commit-slab" mechanism and the field is eliminated.

 * A less often used command "git show-index" has been modernized.
   (merge fb3010c31f jk/show-index later to maint).

 * The conversion to pass "the_repository" and then "a_repository"
   throughout the object access API continues.

 * Continuing with the idea to programatically enumerate various
   pieces of data required for command line completion, teach the
   codebase to report the list of configuration variables
   subcommands care about to help complete them.

 * Separate "rebase -p" codepath out of "rebase -i" implementation to
   slim down the latter and make it easier to manage.

 * Make refspec parsing codepath more robust.

 * Some flaky tests have been fixed.

 * Continuing with the idea to programmatically enumerate various
   pieces of data required for command line completion, the codebase
   has been taught to enumerate options prefixed with "--no-" to
   negate them.

 * Build and test procedure for netrc credential helper (in contrib/)
   has been updated.

 * Remove unused function definitions and declarations from ewah
   bitmap subsystem.

 * Code preparation to make "git p4" closer to be usable with Python 3.

 * Tighten the API to make it harder to misuse in-tree .gitmodules
   file, even though it shares the same syntax with configuration
   files, to read random configuration items from it.

 * "git fast-import" has been updated to avoid attempting to create
   delta against a zero-byte-long string, which is pointless.

 * The codebase has been updated to compile cleanly with -pedantic
   option.
   (merge 2b647a05d7 bb/pedantic later to maint).

 * The character display width table has been updated to match the
   latest Unicode standard.
   (merge 570951eea2 bb/unicode-11-width later to maint).

 * test-lint now looks for broken use of "VAR=VAL shell_func" in test
   scripts.

 * Conversion from uchar[40] to struct object_id continues.

 * Recent "security fix" to pay attention to contents of ".gitmodules"
   while accepting "git push" was a bit overly strict than necessary,
   which has been adjusted.

 * "git fsck" learns to make sure the optional commit-graph file is in
   a sane state.

 * "git diff --color-moved" feature has further been tweaked.

 * Code restructuring and a small fix to transport protocol v2 during
   fetching.

 * Parsing of -L[<N>][,[<M>]] parameters "git blame" and "git log"
   take has been tweaked.

 * lookup_commit_reference() and friends have been updated to find
   in-core object for a specific in-core repository instance.

 * Various glitches in the heuristics of merge-recursive strategy have
   been documented in new tests.

 * "git fetch" learned a new option "--negotiation-tip" to limit the
   set of commits it tells the other end as "have", to reduce wasted
   bandwidth and cycles, which would be helpful when the receiving
   repository has a lot of refs that have little to do with the
   history at the remote it is fetching from.

 * For a large tree, the index needs to hold many cache entries
   allocated on heap.  These cache entries are now allocated out of a
   dedicated memory pool to amortize malloc(3) overhead.

 * Tests to cover various conflicting cases have been added for
   merge-recursive.

 * Tests to cover conflict cases that involve submodules have been
   added for merge-recursive.

 * Look for broken "&&" chains that are hidden in subshell, many of
   which have been found and corrected.

 * The singleton commit-graph in-core instance is made per in-core
   repository instance.

 * "make DEVELOPER=1 DEVOPTS=pedantic" allows developers to compile
   with -pedantic option, which may catch more problematic program
   constructs and potential bugs.

 * Preparatory code to later add json output for telemetry data has
   been added.

 * Update the way we use Coccinelle to find out-of-style code that
   need to be modernised.

 * It is too easy to misuse system API functions such as strcat();
   these selected functions are now forbidden in this codebase and
   will cause a compilation failure.

 * Add a script (in contrib/) to help users of VSCode work better with
   our codebase.

 * The Travis CI scripts were taught to ship back the test data from
   failed tests.
   (merge aea8879a6a sg/travis-retrieve-trash-upon-failure later to maint).

 * The parse-options machinery learned to refrain from enclosing
   placeholder string inside a "<bra" and "ket>" pair automatically
   without PARSE_OPT_LITERAL_ARGHELP.  Existing help text for option
   arguments that are not formatted correctly have been identified and
   fixed.
   (merge 5f0df44cd7 rs/parse-opt-lithelp later to maint).

 * Noiseword "extern" has been removed from function decls in the
   header files.

 * A few atoms like %(objecttype) and %(objectsize) in the format
   specifier of "for-each-ref --format=<format>" can be filled without
   getting the full contents of the object, but just with the object
   header.  These cases have been optimized by calling
   oid_object_info() API (instead of reading and inspecting the data).

 * The end result of documentation update has been made to be
   inspected more easily to help developers.

 * The API to iterate over all objects learned to optionally list
   objects in the order they appear in packfiles, which helps locality
   of access if the caller accesses these objects while as objects are
   enumerated.

 * Improve built-in facility to catch broken &&-chain in the tests.

 * The more library-ish parts of the codebase learned to work on the
   in-core index-state instance that is passed in by their callers,
   instead of always working on the singleton "the_index" instance.

 * A test prerequisite defined by various test scripts with slightly
   different semantics has been consolidated into a single copy and
   made into a lazily defined one.
   (merge 6ec633059a wc/make-funnynames-shared-lazy-prereq later to maint).

 * After a partial clone, repeated fetches from promisor remote would
   have accumulated many packfiles marked with .promisor bit without
   getting them coalesced into fewer packfiles, hurting performance.
   "git repack" now learned to repack them.

 * Partially revert the support for multiple hash functions to regain
   hash comparison performance; we'd think of a way to do this better
   in the next cycle.

 * "git help --config" (which is used in command line completion)
   missed the configuration variables not described in the main
   config.txt file but are described in another file that is included
   by it, which has been corrected.

 * The test linter code has learned that the end of here-doc mark
   "EOF" can be quoted in a double-quote pair, not just in a
   single-quote pair.


(adam)