Documentation / RelNotes / 2.10.0.txton commit i18n: simplify numeric error reporting (078fe30)
   1Git 2.10 Release Notes
   2======================
   3
   4Backward compatibility notes
   5----------------------------
   6
   7Updates since v2.9
   8------------------
   9
  10UI, Workflows & Features
  11
  12 * "git pull --rebase --verify-signature" learned to warn the user
  13   that "--verify-signature" is a no-op when rebasing.
  14
  15 * An upstream project can make a recommendation to shallowly clone
  16   some submodules in the .gitmodules file it ships.
  17
  18 * "git worktree add" learned that '-' can be used as a short-hand for
  19   "@{-1}", the previous branch.
  20
  21 * Update the funcname definition to support css files.
  22
  23 * The completion script (in contrib/) learned to complete "git
  24   status" options.
  25
  26 * Messages that are generated by auto gc during "git push" on the
  27   receiving end are now passed back to the sending end in such a way
  28   that they are shown with "remote: " prefix to avoid confusing the
  29   users.
  30
  31 * "git add -i/-p" learned to honor diff.compactionHeuristic
  32   experimental knob, so that the user can work on the same hunk split
  33   as "git diff" output.
  34
  35 * "upload-pack" allows a custom "git pack-objects" replacement when
  36   responding to "fetch/clone" via the uploadpack.packObjectsHook.
  37   (merge b738396 jk/upload-pack-hook later to maint).
  38
  39 * Teach format-patch and mailsplit (hence "am") how a line that
  40   happens to begin with "From " in the e-mail message is quoted with
  41   ">", so that these lines can be restored to their original shape.
  42   (merge d9925d1 ew/mboxrd-format-am later to maint).
  43
  44 * "git repack" learned the "--keep-unreachable" option, which sends
  45   loose unreachable objects to a pack instead of leaving them loose.
  46   This helps heuristics based on the number of loose objects
  47   (e.g. "gc --auto").
  48   (merge e26a8c4 jk/repack-keep-unreachable later to maint).
  49
  50 * "log --graph --format=" learned that "%>|(N)" specifies the width
  51   relative to the terminal's left edge, not relative to the area to
  52   draw text that is to the right of the ancestry-graph section.  It
  53   also now accepts negative N that means the column limit is relative
  54   to the right border.
  55
  56 * A careless invocation of "git send-email directory/" after editing
  57   0001-change.patch with an editor often ends up sending both
  58   0001-change.patch and its backup file, 0001-change.patch~, causing
  59   embarrassment and a minor confusion.  Detect such an input and
  60   offer to skip the backup files when sending the patches out.
  61   (merge 531220b jc/send-email-skip-backup later to maint).
  62
  63 * "git submodule update" that drives many "git clone" could
  64   eventually hit flaky servers/network conditions on one of the
  65   submodules; the command learned to retry the attempt.
  66
  67 * The output coloring scheme learned two new attributes, italic and
  68   strike, in addition to existing bold, reverse, etc.
  69
  70 * "git log" learns log.showSignature configuration variable, and a
  71   command line option "--no-show-signature" to countermand it.
  72   (merge fce04c3 mj/log-show-signature-conf later to maint).
  73
  74 * More markings of messages for i18n, with updates to various tests
  75   to pass GETTEXT_POISON tests.
  76
  77 * "git archive" learned to handle files that are larger than 8GB and
  78   commits far in the future than expressible by the traditional US-TAR
  79   format.
  80   (merge 5caeeb8 jk/big-and-future-archive-tar later to maint).
  81
  82 * A new configuration variable core.sshCommand has been added to
  83   specify what value for GIT_SSH_COMMAND to use per repository.
  84
  85 * "git worktree prune" protected worktrees that are marked as
  86   "locked" by creating a file in a known location.  "git worktree"
  87   command learned a dedicated command pair to create and remove such
  88   a file, so that the users do not have to do this with editor.
  89
  90 * A handful of "git svn" updates.
  91
  92 * "git push" learned to accept and pass extra options to the
  93   receiving end so that hooks can read and react to them.
  94
  95 * "git status" learned to suggest "merge --abort" during a conflicted
  96   merge, just like it already suggests "rebase --abort" during a
  97   conflicted rebase.
  98
  99 * "git jump" script (in contrib/) has been updated a bit.
 100   (merge a91e692 jk/git-jump later to maint).
 101
 102 * "git push" and "git clone" learned to give better progress meters
 103   to the end user who is waiting on the terminal.
 104
 105 * An entry "git log --decorate" for the tip of the current branch is
 106   shown as "HEAD -> name" (where "name" is the name of the branch);
 107   the arrow is now painted in the same color as "HEAD", not in the
 108   color for commits.
 109
 110 * "git format-patch" learned format.from configuration variable to
 111   specify the default settings for its "--from" option.
 112
 113 * "git am -3" calls "git merge-recursive" when it needs to fall back
 114   to a three-way merge; this call has been turned into an internal
 115   subroutine call instead of spawning a separate subprocess.
 116
 117 * The command line completion scripts (in contrib/) now knows about
 118   "git branch --delete/--move [--remote]".
 119   (merge 2703c22 vs/completion-branch-fully-spelled-d-m-r later to maint).
 120
 121 * "git rev-parse --git-path hooks/<hook>" learned to take
 122   core.hooksPath configuration variable (introduced during 2.9 cycle)
 123   into account.
 124   (merge 9445b49 ab/hooks later to maint).
 125
 126 * "git log --show-signature" and other commands that display the
 127   verification status of PGP signature now shows the longer key-id,
 128   as 32-bit key-id is so last century.
 129
 130
 131Performance, Internal Implementation, Development Support etc.
 132
 133 * "git fast-import" learned the same performance trick to avoid
 134   creating too small a packfile as "git fetch" and "git push" have,
 135   using *.unpackLimit configuration.
 136
 137 * When "git daemon" is run without --[init-]timeout specified, a
 138   connection from a client that silently goes offline can hang around
 139   for a long time, wasting resources.  The socket-level KEEPALIVE has
 140   been enabled to allow the OS to notice such failed connections.
 141
 142 * "git upload-pack" command has been updated to use the parse-options
 143   API.
 144
 145 * The "git apply" standalone program is being libified; the first
 146   step to move many state variables into a structure that can be
 147   explicitly (re)initialized to make the machinery callable more
 148   than once has been merged.
 149
 150 * HTTP transport gained an option to produce more detailed debugging
 151   trace.
 152   (merge 73e57aa ep/http-curl-trace later to maint).
 153
 154 * Instead of taking advantage of the fact that a struct string_list
 155   that is allocated with all NULs happens to be the INIT_NODUP kind,
 156   the users of string_list structures are taught to initialize them
 157   explicitly as such, to document their behaviour better.
 158   (merge 2721ce2 jk/string-list-static-init later to maint).
 159
 160 * HTTPd tests learned to show the server error log to help diagnosing
 161   a failing tests.
 162   (merge 44f243d nd/test-lib-httpd-show-error-log-in-verbose later to maint).
 163
 164 * The ownership rule for the piece of memory that hold references to
 165   be fetched in "git fetch" was screwy, which has been cleaned up.
 166
 167 * "git bisect" makes an internal call to "git diff-tree" when
 168   bisection finds the culprit, but this call did not initialize the
 169   data structure to pass to the diff-tree API correctly.
 170
 171 * Further preparatory clean-up for "worktree" feature continues.
 172   (merge 0409e0b nd/worktree-cleanup-post-head-protection later to maint).
 173
 174 * Formats of the various data (and how to validate them) where we use
 175   GPG signature have been documented.
 176
 177 * A new run-command API function pipe_command() is introduced to
 178   sanely feed data to the standard input while capturing data from
 179   the standard output and the standard error of an external process,
 180   which is cumbersome to hand-roll correctly without deadlocking.
 181
 182   The codepath to sign data in a prepared buffer with GPG has been
 183   updated to use this API to read from the status-fd to check for
 184   errors (instead of relying on GPG's exit status).
 185   (merge efee955 jk/gpg-interface-cleanup later to maint).
 186
 187 * Allow t/perf framework to use the features from the most recent
 188   version of Git even when testing an older installed version.
 189
 190 * The commands in the "log/diff" family have had an FILE* pointer in the
 191   data structure they pass around for a long time, but some codepaths
 192   used to always write to the standard output.  As a preparatory step
 193   to make "git format-patch" available to the internal callers, these
 194   codepaths have been updated to consistently write into that FILE*
 195   instead.
 196
 197 * Conversion from unsigned char sha1[20] to struct object_id
 198   continues.
 199
 200 * Improve the look of the way "git fetch" reports what happened to
 201   each ref that was fetched.
 202
 203 * The .c/.h sources are marked as such in our .gitattributes file so
 204   that "git diff -W" and friends would work better.
 205
 206 * Code clean-up to avoid using a variable string that compilers may
 207   feel untrustable as printf-style format given to write_file()
 208   helper function.
 209
 210 * "git p4" used a location outside $GIT_DIR/refs/ to place its
 211   temporary branches, which has been moved to refs/git-p4-tmp/.
 212
 213 * Existing autoconf generated test for the need to link with pthread
 214   library did not check all the functions from pthread libraries;
 215   recent FreeBSD has some functions in libc but not others, and we
 216   mistakenly thought linking with libc is enough when it is not.
 217
 218 * When "git fsck" reports a broken link (e.g. a tree object contains
 219   a blob that does not exist), both containing object and the object
 220   that is referred to were reported with their 40-hex object names.
 221   The command learned the "--name-objects" option to show the path to
 222   the containing object from existing refs (e.g. "HEAD~24^2:file.txt").
 223
 224 * Allow http daemon tests in Travis CI tests.
 225
 226 * Makefile assumed that -lrt is always available on platforms that
 227   want to use clock_gettime() and CLOCK_MONOTONIC, which is not a
 228   case for recent Mac OS X.  The necessary symbols are often found in
 229   libc on many modern systems and having -lrt on the command line, as
 230   long as the library exists, had no effect, but when the platform
 231   removes librt.a that is a different matter--having -lrt will break
 232   the linkage.
 233
 234   This change could be seen as a regression for those who do need to
 235   specify -lrt, as they now specifically ask for NEEDS_LIBRT when
 236   building. Hopefully they are in the minority these days.
 237
 238 * Further preparatory work on the refs API before the pluggable
 239   backend series can land.
 240
 241 * Error handling in the codepaths that updates refs has been
 242   improved.
 243
 244 * The API to iterate over all the refs (i.e. for_each_ref(), etc.)
 245   has been revamped.
 246
 247 * The handling of the "text=auto" attribute has been corrected.
 248   $ echo "* text=auto eol=crlf" >.gitattributes
 249   used to have the same effect as
 250   $ echo "* text eol=crlf" >.gitattributes
 251   i.e. declaring all files are text (ignoring "auto").  The
 252   combination has been fixed to be equivalent to doing
 253   $ git config core.autocrlf true
 254
 255 * A few tests that specifically target "git rebase -i" have been
 256   added.
 257
 258 * Dumb http transport on the client side has been optimized.
 259   (merge ecba195 ew/http-walker later to maint).
 260
 261 * Users of the parse_options_concat() API function need to allocate
 262   extra slots in advance and fill them with OPT_END() when they want
 263   to decide the set of supported options dynamically, which makes the
 264   code error-prone and hard to read.  This has been corrected by tweaking
 265   the API to allocate and return a new copy of "struct option" array.
 266
 267 * "git fetch" exchanges batched have/ack messages between the sender
 268   and the receiver, initially doubling every time and then falling
 269   back to enlarge the window size linearly.  The "smart http"
 270   transport, being an half-duplex protocol, outgrows the preset limit
 271   too quickly and becomes inefficient when interacting with a large
 272   repository.  The internal mechanism learned to grow the window size
 273   more aggressively when working with the "smart http" transport.
 274
 275 * Tests for "git svn" have been taught to reuse the lib-httpd test
 276   infrastructure when testing the subversion integration that
 277   interacts with subversion repositories served over the http://
 278   protocol.
 279   (merge a8a5d25 ew/git-svn-http-tests later to maint).
 280
 281 * "git pack-objects" has a few options that tell it not to pack
 282   objects found in certain packfiles, which require it to scan .idx
 283   files of all available packs.  The codepaths involved in these
 284   operations have been optimized for a common case of not having any
 285   non-local pack and/or any .kept pack.
 286
 287 * The t3700 test about "add --chmod=-x" have been made a bit more
 288   robust and generally cleaned up.
 289   (merge 766cdc4 ib/t3700-add-chmod-x-updates later to maint).
 290
 291 * The build procedure learned PAGER_ENV knob that lists what default
 292   environment variable settings to export for popular pagers.  This
 293   mechanism is used to tweak the default settings to MORE on FreeBSD.
 294   (merge 995bc22 ew/build-time-pager-tweaks later to maint).
 295
 296 * The http-backend (the server-side component of smart-http
 297   transport) used to trickle the HTTP header one at a time.  Now
 298   these write(2)s are batched.
 299   (merge b36045c ew/http-backend-batch-headers later to maint).
 300
 301 * When "git rebase" tries to compare set of changes on the updated
 302   upstream and our own branch, it computes patch-id for all of these
 303   changes and attempts to find matches. This has been optimized by
 304   lazily computing the full patch-id (which is expensive) to be
 305   compared only for changes that touch the same set of paths.
 306   (merge b3dfeeb kw/patch-ids-optim later to maint).
 307
 308 * A handful of tests that were broken under gettext-poison build have
 309   been fixed.
 310
 311
 312Also contains various documentation updates and code clean-ups.
 313
 314
 315Fixes since v2.9
 316----------------
 317
 318Unless otherwise noted, all the fixes since v2.8 in the maintenance
 319track are contained in this release (see the maintenance releases'
 320notes for details).
 321
 322 * The commands in `git log` family take %C(auto) in a custom format
 323   string.  This unconditionally turned the color on, ignoring
 324   --no-color or with --color=auto when the output is not connected to
 325   a tty; this was corrected to make the format truly behave as
 326   "auto".
 327
 328 * "git rev-list --count" whose walk-length is limited with "-n"
 329   option did not work well with the counting optimized to look at the
 330   bitmap index.
 331
 332 * "git show -W" (extend hunks to cover the entire function, delimited
 333   by lines that match the "funcname" pattern) used to show the entire
 334   file when a change added an entire function at the end of the file,
 335   which has been fixed.
 336
 337 * The documentation set has been updated so that literal commands,
 338   configuration variables and environment variables are consistently
 339   typeset in fixed-width font and bold in manpages.
 340
 341 * "git svn propset" subcommand that was added in 2.3 days is
 342   documented now.
 343
 344 * The documentation tries to consistently spell "GPG"; when
 345   referring to the specific program name, "gpg" is used.
 346
 347 * "git reflog" stopped upon seeing an entry that denotes a branch
 348   creation event (aka "unborn"), which made it appear as if the
 349   reflog was truncated.
 350
 351 * The git-prompt scriptlet (in contrib/) was not friendly with those
 352   who uses "set -u", which has been fixed.
 353
 354 * compat/regex code did not cleanly compile.
 355
 356 * A codepath that used alloca(3) to place an unbounded amount of data
 357   on the stack has been updated to avoid doing so.
 358
 359 * "git update-index --add --chmod=+x file" may be usable as an escape
 360   hatch, but not a friendly thing to force for people who do need to
 361   use it regularly.  "git add --chmod=+x file" can be used instead.
 362
 363 * Build improvements for gnome-keyring (in contrib/)
 364
 365 * "git status" used to say "working directory" when it meant "working
 366   tree".
 367
 368 * Comments about misbehaving FreeBSD shells have been clarified with
 369   the version number (9.x and before are broken, newer ones are OK).
 370
 371 * "git cherry-pick A" worked on an unborn branch, but "git
 372   cherry-pick A..B" didn't.
 373
 374 * Fix an unintended regression in v2.9 that breaks "clone --depth"
 375   that recurses down to submodules by forcing the submodules to also
 376   be cloned shallowly, which many server instances that host upstream
 377   of the submodules are not prepared for.
 378
 379 * Fix unnecessarily waste in the idiomatic use of ': ${VAR=default}'
 380   to set the default value, without enclosing it in double quotes.
 381
 382 * Some platform-specific code had non-ANSI strict declarations of C
 383   functions that do not take any parameters, which has been
 384   corrected.
 385
 386 * The internal code used to show local timezone offset is not
 387   prepared to handle timestamps beyond year 2100, and gave a
 388   bogus offset value to the caller.  Use a more benign looking
 389   +0000 instead and let "git log" going in such a case, instead
 390   of aborting.
 391
 392 * One among four invocations of readlink(1) in our test suite has
 393   been rewritten so that the test can run on systems without the
 394   command (others are in valgrind test framework and t9802).
 395
 396 * t/perf needs /usr/bin/time with GNU extension; the invocation of it
 397   is updated to "gtime" on Darwin.
 398
 399 * A bug, which caused "git p4" while running under verbose mode to
 400   report paths that are omitted due to branch prefix incorrectly, has
 401   been fixed; the command said "Ignoring file outside of prefix" for
 402   paths that are _inside_.
 403
 404 * The top level documentation "git help git" still pointed at the
 405   documentation set hosted at now-defunct google-code repository.
 406   Update it to point to https://git.github.io/htmldocs/git.html
 407   instead.
 408
 409 * A helper function that takes the contents of a commit object and
 410   finds its subject line did not ignore leading blank lines, as is
 411   commonly done by other codepaths.  Make it ignore leading blank
 412   lines to match.
 413
 414 * For a long time, we carried an in-code comment that said our
 415   colored output would work only when we use fprintf/fputs on
 416   Windows, which no longer is the case for the past few years.
 417
 418 * "gc.autoPackLimit" when set to 1 should not trigger a repacking
 419   when there is only one pack, but the code counted poorly and did
 420   so.
 421
 422 * Add a test to specify the desired behaviour that currently is not
 423   available in "git rebase -Xsubtree=...".
 424
 425 * More mark-up updates to typeset strings that are expected to
 426   literally typed by the end user in fixed-width font.
 427
 428 * "git commit --amend --allow-empty-message -S" for a commit without
 429   any message body could have misidentified where the header of the
 430   commit object ends.
 431
 432 * "git rebase -i --autostash" did not restore the auto-stashed change
 433   when the operation was aborted.
 434
 435 * Git does not know what the contents in the index should be for a
 436   path added with "git add -N" yet, so "git grep --cached" should not
 437   show hits (or show lack of hits, with -L) in such a path, but that
 438   logic does not apply to "git grep", i.e. searching in the working
 439   tree files.  But we did so by mistake, which has been corrected.
 440
 441 * "git blame -M" missed a single line that was moved within the file.
 442
 443 * Fix recently introduced codepaths that are involved in parallel
 444   submodule operations, which gave up on reading too early, and
 445   could have wasted CPU while attempting to write under a corner
 446   case condition.
 447
 448 * "git grep -i" has been taught to fold case in non-ascii locales
 449   correctly.
 450
 451 * A test that unconditionally used "mktemp" learned that the command
 452   is not necessarily available everywhere.
 453
 454 * There are certain house-keeping tasks that need to be performed at
 455   the very beginning of any Git program, and programs that are not
 456   built-in commands had to do them exactly the same way as "git"
 457   potty does.  It was easy to make mistakes in one-off standalone
 458   programs (like test helpers).  A common "main()" function that
 459   calls cmd_main() of individual program has been introduced to
 460   make it harder to make mistakes.
 461   (merge de61ceb jk/common-main later to maint).
 462
 463 * The test framework learned a new helper test_match_signal to
 464   check an exit code from getting killed by an expected signal.
 465
 466 * General code clean-up around a helper function to write a
 467   single-liner to a file.
 468   (merge 7eb6e10 jk/write-file later to maint).
 469
 470 * One part of "git am" had an oddball helper function that called
 471   stuff from outside "his" as opposed to calling what we have "ours",
 472   which was not gender-neutral and also inconsistent with the rest of
 473   the system where outside stuff is usuall called "theirs" in
 474   contrast to "ours".
 475
 476 * "git blame file" allowed the lineage of lines in the uncommitted,
 477   unadded contents of "file" to be inspected, but it refused when
 478   "file" did not appear in the current commit.  When "file" was
 479   created by renaming an existing file (but the change has not been
 480   committed), this restriction was unnecessarily tight.
 481
 482 * "git add -N dir/file && git write-tree" produced an incorrect tree
 483   when there are other paths in the same directory that sorts after
 484   "file".
 485
 486 * "git fetch http://user:pass@host/repo..." scrubbed the userinfo
 487   part, but "git push" didn't.
 488
 489 * "git merge" with renormalization did not work well with
 490   merge-recursive, due to "safer crlf" conversion kicking in when it
 491   shouldn't.
 492   (merge 1335d76 jc/renormalize-merge-kill-safer-crlf later to maint).
 493
 494 * The use of strbuf in "git rm" to build filename to remove was a bit
 495   suboptimal, which has been fixed.
 496
 497 * An age old bug that caused "git diff --ignore-space-at-eol"
 498   misbehave has been fixed.
 499
 500 * "git notes merge" had a code to see if a path exists (and fails if
 501   it does) and then open the path for writing (when it doesn't).
 502   Replace it with open with O_EXCL.
 503
 504 * "git pack-objects" and "git index-pack" mostly operate with off_t
 505   when talking about the offset of objects in a packfile, but there
 506   were a handful of places that used "unsigned long" to hold that
 507   value, leading to an unintended truncation.
 508
 509 * Recent update to "git daemon" tries to enable the socket-level
 510   KEEPALIVE, but when it is spawned via inetd, the standard input
 511   file descriptor may not necessarily be connected to a socket.
 512   Suppress an ENOTSOCK error from setsockopt().
 513
 514 * Recent FreeBSD stopped making perl available at /usr/bin/perl;
 515   switch the default the built-in path to /usr/local/bin/perl on not
 516   too ancient FreeBSD releases.
 517
 518 * "git commit --help" said "--no-verify" is only about skipping the
 519   pre-commit hook, and failed to say that it also skipped the
 520   commit-msg hook.
 521
 522 * "git merge" in Git v2.9 was taught to forbid merging an unrelated
 523   lines of history by default, but that is exactly the kind of thing
 524   the "--rejoin" mode of "git subtree" (in contrib/) wants to do.
 525   "git subtree" has been taught to use the "--allow-unrelated-histories"
 526   option to override the default.
 527
 528 * The build procedure for "git persistent-https" helper (in contrib/)
 529   has been updated so that it can be built with more recent versions
 530   of Go.
 531
 532 * There is an optimization used in "git diff $treeA $treeB" to borrow
 533   an already checked-out copy in the working tree when it is known to
 534   be the same as the blob being compared, expecting that open/mmap of
 535   such a file is faster than reading it from the object store, which
 536   involves inflating and applying delta.  This however kicked in even
 537   when the checked-out copy needs to go through the convert-to-git
 538   conversion (including the clean filter), which defeats the whole
 539   point of the optimization.  The optimization has been disabled when
 540   the conversion is necessary.
 541
 542 * "git -c grep.patternType=extended log --basic-regexp" misbehaved
 543   because the internal API to access the grep machinery was not
 544   designed well.
 545
 546 * Windows port was failing some tests in t4130, due to the lack of
 547   inum in the returned values by its lstat(2) emulation.
 548
 549 * The reflog output format is documented better, and a new format
 550   --date=unix to report the seconds-since-epoch (without timezone)
 551   has been added.
 552   (merge 442f6fd jk/reflog-date later to maint).
 553
 554 * "git difftool <paths>..." started in a subdirectory failed to
 555   interpret the paths relative to that directory, which has been
 556   fixed.
 557
 558 * The characters in the label shown for tags/refs for commits in
 559   "gitweb" output are now properly escaped for proper HTML output.
 560
 561 * FreeBSD can lie when asked mtime of a directory, which made the
 562   untracked cache code to fall back to a slow-path, which in turn
 563   caused tests in t7063 to fail because it wanted to verify the
 564   behaviour of the fast-path.
 565
 566 * Squelch compiler warnings for netmalloc (in compat/) library.
 567
 568 * A small memory leak in the command line parsing of "git blame"
 569   has been plugged.
 570
 571 * The API documentation for hashmap was unclear if hashmap_entry
 572   can be safely discarded without any other consideration.  State
 573   that it is safe to do so.
 574
 575 * Not-so-recent rewrite of "git am" that started making internal
 576   calls into the commit machinery had an unintended regression, in
 577   that no matter how many seconds it took to apply many patches, the
 578   resulting committer timestamp for the resulting commits were all
 579   the same.
 580
 581 * "git push --force-with-lease" already had enough logic to allow
 582   ensuring that such a push results in creation of a ref (i.e. the
 583   receiving end did not have another push from sideways that would be
 584   discarded by our force-pushing), but didn't expose this possibility
 585   to the users.  It does so now.
 586   (merge 9eed4f3 jk/push-force-with-lease-creation later to maint).
 587
 588 * The mechanism to limit the pack window memory size, when packing is
 589   done using multiple threads (which is the default), is per-thread,
 590   but this was not documented clearly.
 591   (merge 954176c ms/document-pack-window-memory-is-per-thread later to maint).
 592
 593 * "import-tars" fast-import script (in contrib/) used to ignore a
 594   hardlink target and replaced it with an empty file, which has been
 595   corrected to record the same blob as the other file the hardlink is
 596   shared with.
 597   (merge 04e0869 js/import-tars-hardlinks later to maint).
 598
 599 * "git mv dir non-existing-dir/" did not work in some environments
 600   the same way as existing mainstream platforms.  The code now moves
 601   "dir" to "non-existing-dir", without relying on rename("A", "B/")
 602   that strips the trailing slash of '/'.
 603   (merge 189d035 js/mv-dir-to-new-directory later to maint).
 604
 605 * The "t/" hierarchy is prone to get an unusual pathname; "make test"
 606   has been taught to make sure they do not contain paths that cannot
 607   be checked out on Windows (and the mechanism can be reusable to
 608   catch pathnames that are not portable to other platforms as need
 609   arises).
 610   (merge c2cafd3 js/test-lint-pathname later to maint).
 611
 612 * When "git merge-recursive" works on history with many criss-cross
 613   merges in "verbose" mode, the names the command assigns to the
 614   virtual merge bases could have overwritten each other by unintended
 615   reuse of the same piece of memory.
 616   (merge 5447a76 rs/pull-signed-tag later to maint).
 617
 618 * "git checkout --detach <branch>" used to give the same advice
 619   message as that is issued when "git checkout <tag>" (or anything
 620   that is not a branch name) is given, but asking with "--detach" is
 621   an explicit enough sign that the user knows what is going on.  The
 622   advice message has been squelched in this case.
 623   (merge 779b88a sb/checkout-explit-detach-no-advice later to maint).
 624
 625 * "git difftool" by default ignores the error exit from the backend
 626   commands it spawns, because often they signal that they found
 627   differences by exiting with a non-zero status code just like "diff"
 628   does; the exit status codes 126 and above however are special in
 629   that they are used to signal that the command is not executable,
 630   does not exist, or killed by a signal.  "git difftool" has been
 631   taught to notice these exit status codes.
 632   (merge 45a4f5d jk/difftool-command-not-found later to maint).
 633
 634 * Other minor clean-ups and documentation updates
 635   (merge 02a8cfa rs/merge-add-strategies-simplification later to maint).
 636   (merge af4941d rs/merge-recursive-string-list-init later to maint).
 637   (merge 1eb47f1 rs/use-strbuf-add-unique-abbrev later to maint).
 638   (merge ddd0bfa jk/tighten-alloc later to maint).
 639   (merge ecf30b2 rs/mailinfo-lib later to maint).
 640   (merge 0eb75ce sg/reflog-past-root later to maint).