Bugfix.

* sb/diff-color-move-more:
  diff: fix --color-moved-ws=allow-indentation-change

A corner case bugfix in "git rerere" code.

* en/rerere-multi-stage-1-fix:
  rerere: avoid buffer overrun
  t4200: demonstrate rerere segfault on specially crafted merge

Further fix for O_APPEND emulation on Windows

* js/mingw-o-append:
  mingw: fix mingw_open_append to work with named pipes
  t0051: test GIT_TRACE to a windows named pipe

Code clean-up.

* en/double-semicolon-fix:
  Remove superfluous trailing semicolons

Fix for a long-standing bug that leaves the index file corrupt when
it shrinks during a partial commit.

* jk/reopen-tempfile-truncate:
  reopen_tempfile(): truncate opened file

When fsmonitor is in use, after operation on submodules updates
.gitmodules, we lost track of the fact that we did so and relied on
stale fsmonitor data.

* bp/mv-submodules-with-fsmonitor:
  git-mv: allow submodules and fsmonitor to work together

* ds/format-patch-range-diff-test:
  t3206-range-diff.sh: cover single-patch case

Code clean-up.

* tb/void-check-attr:
  Make git_check_attr() a void function

"git rebase -i" did not clear the state files correctly when a run
of "squash/fixup" is aborted and then the user manually amended the
commit instead, which has been corrected.

* js/rebase-i-autosquash-fix:
  rebase -i: be careful to wrap up fixup/squash chains
  rebase -i --autosquash: demonstrate a problem skipping the last squash

The rules used by "git push" and "git fetch" to determine if a ref
can or cannot be updated were inconsistent; specifically, fetching
to update existing tags were allowed even though tags are supposed
to be unmoving anchoring points.  "git fetch" was taught to forbid
updates to existing tags without the "--force" option.
This is a backward incompatible change but in a good way; it may
still need to be treated carefully.

* ab/fetch-tags-noclobber:
  fetch doc: correct grammar in --force docs
  push doc: add spacing between two words

"git checkout -b newbranch [HEAD]" should not have to do as much as
checking out a commit different from HEAD.  An attempt is made to
optimize this special case.

* bp/checkout-new-branch-optim:
  config doc: add missing list separator for checkout.optimizeNewBranch

Correct a grammar error (saying "the receiving" made no sense) in the
recently landed documentation added in my 0bc8d71b ("fetch: stop
clobbering existing tags without --force", 2018-08-31) by rephrasing
the sentence.  Also correct 'fetching work the same way' by s/work/&s/;
Signed-off-by: NÆvar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Fix a formatting error introduced in my recently landed
fe802bd2 ("push doc: correct lies about how push refspecs work",
2018-08-31).
Signed-off-by: NÆvar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The documentation added in fa655d84 ("checkout: optimize "git
checkout -b <new_branch>"", 2018-08-16) didn't add the double-colon
needed for the labeled list separator, as a result the added
documentation all got squashed into one paragraph. Fix that by adding
the list separator.
Signed-off-by: NÆvar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Debugging aid update.

* nd/bisect-show-list-fix:
  bisect.c: make show_list() build again

The rules used by "git push" and "git fetch" to determine if a ref
can or cannot be updated were inconsistent; specifically, fetching
to update existing tags were allowed even though tags are supposed
to be unmoving anchoring points.  "git fetch" was taught to forbid
updates to existing tags without the "--force" option.

* ab/fetch-tags-noclobber:
  fetch: stop clobbering existing tags without --force
  fetch: document local ref updates with/without --force
  push doc: correct lies about how push refspecs work
  push doc: move mention of "tag <tag>" later in the prose
  push doc: remove confusing mention of remote merger
  fetch tests: add a test for clobbering tag behavior
  push tests: use spaces in interpolated string
  push tests: make use of unused $1 in test description
  fetch: change "branch" to "reference" in --force -h output

Fix a bug in which the same path could be registered under multiple
worktree entries if the path was missing (for instance, was removed
manually).  Also, as a convenience, expand the number of cases in
which --force is applicable.

* es/worktree-forced-ops-fix:
  doc-diff: force worktree add
  worktree: delete .git/worktrees if empty after 'remove'
  worktree: teach 'remove' to override lock when --force given twice
  worktree: teach 'move' to override lock when --force given twice
  worktree: teach 'add' to respect --force for registered but missing path
  worktree: disallow adding same path multiple times
  worktree: prepare for more checks of whether path can become worktree
  worktree: generalize delete_git_dir() to reduce code duplication
  worktree: move delete_git_dir() earlier in file for upcoming new callers
  worktree: don't die() in library function find_worktree()

Docfix.

* sg/doc-trace-appends:
  Documentation/git.txt: clarify that GIT_TRACE=/path appends

Dev doc update.

* jk/diff-rendered-docs:
  Revert "doc/Makefile: drop doc-diff worktree and temporary files on "make clean""
  doc/Makefile: drop doc-diff worktree and temporary files on "make clean"
  doc-diff: add --clean mode to remove temporary working gunk
  doc-diff: fix non-portable 'man' invocation
  doc-diff: always use oids inside worktree
  SubmittingPatches: mention doc-diff

Malformed or crafted data in packstream can make our code attempt
to read or write past the allocated buffer and abort, instead of
reporting an error, which has been fixed.

* jk/patch-corrupted-delta-fix:
  t5303: use printf to generate delta bases
  patch-delta: handle truncated copy parameters
  patch-delta: consistently report corruption
  patch-delta: fix oob read
  t5303: test some corrupt deltas
  test-delta: read input into a heap buffer

We can now optionally run tests with commit-graph enabled.

* ds/commit-graph-tests:
  commit-graph: define GIT_TEST_COMMIT_GRAPH

Hotfix of the base topic.

* jk/pack-objects-with-bitmap-fix:
  pack-bitmap: drop "loaded" flag
  traverse_bitmap_commit_list(): don't free result
  t5310: test delta reuse with bitmaps
  bitmap_has_sha1_in_uninteresting(): drop BUG check

"git mailinfo" used in "git am" learned to make a best-effort
recovery of a patch corrupted by MUA that sends text/plain with
format=flawed option.

* rs/mailinfo-format-flowed:
  mailinfo: support format=flowed

spatch transformation to replace boolean uses of !hashcmp() to
newly introduced oideq() is added, and applied, to regain
performance lost due to support of multiple hash algorithms.

* jk/cocci:
  show_dirstat: simplify same-content check
  read-cache: use oideq() in ce_compare functions
  convert hashmap comparison functions to oideq()
  convert "hashcmp() != 0" to "!hasheq()"
  convert "oidcmp() != 0" to "!oideq()"
  convert "hashcmp() == 0" to hasheq()
  convert "oidcmp() == 0" to oideq()
  introduce hasheq() and oideq()
  coccinelle: use <...> for function exclusion

Clarify a part of technical documentation for rerere.

* tg/rerere-doc-updates:
  rerere: add note about files with existing conflict markers
  rerere: mention caveat about unmatched conflict markers

"git format-patch" learned a new "--range-diff" option to explain
the difference between this version and the previous attempt in
the cover letter (or after the tree-dashes as a comment).

* es/format-patch-rangediff:
  format-patch: allow --range-diff to apply to a lone-patch
  format-patch: add --creation-factor tweak for --range-diff
  format-patch: teach --range-diff to respect -v/--reroll-count
  format-patch: extend --range-diff to accept revision range
  format-patch: add --range-diff option to embed diff in cover letter
  range-diff: relieve callers of low-level configuration burden
  range-diff: publish default creation factor
  range-diff: respect diff_option.file rather than assuming 'stdout'

"git format-patch" learned a new "--interdiff" option to explain
the difference between this version and the previous atttempt in
the cover letter (or after the tree-dashes as a comment).

* es/format-patch-interdiff:
  format-patch: allow --interdiff to apply to a lone-patch
  log-tree: show_log: make commentary block delimiting reusable
  interdiff: teach show_interdiff() to indent interdiff
  format-patch: teach --interdiff to respect -v/--reroll-count
  format-patch: add --interdiff option to embed diff in cover letter
  format-patch: allow additional generated content in make_cover_letter()

Lift code from GitHub to restrict delta computation so that an
object that exists in one fork is not made into a delta against
another object that does not appear in the same forked repository.

* cc/delta-islands:
  pack-objects: move 'layer' into 'struct packing_data'
  pack-objects: move tree_depth into 'struct packing_data'
  t5320: tests for delta islands
  repack: add delta-islands support
  pack-objects: add delta-islands support
  pack-objects: refactor code into compute_layer_order()
  Add delta-islands.{c,h}

"git interpret-trailers" and its underlying machinery had a buggy
code that attempted to ignore patch text after commit log message,
which triggered in various codepaths that will always get the log
message alone and never get such an input.

* jk/trailer-fixes:
  append_signoff: use size_t for string offsets
  sequencer: ignore "---" divider when parsing trailers
  pretty, ref-filter: format %(trailers) with no_divider option
  interpret-trailers: allow suppressing "---" divider
  interpret-trailers: tighten check for "---" patch boundary
  trailer: pass process_trailer_opts to trailer_info_get()
  trailer: use size_t for iterating trailer list
  trailer: use size_t for string offsets

The color output support for recently introduced "range-diff"
command got tweaked a bit.

* sb/range-diff-colors:
  range-diff: indent special lines as context
  range-diff: make use of different output indicators
  diff.c: add --output-indicator-{new, old, context}
  diff.c: rewrite emit_line_0 more understandably
  diff.c: omit check for line prefix in emit_line_0
  diff: use emit_line_0 once per line
  diff.c: add set_sign to emit_line_0
  diff.c: reorder arguments for emit_line_ws_markup
  diff.c: simplify caller of emit_line_0
  t3206: add color test for range-diff --dual-color
  test_decode_color: understand FAINT and ITALIC

When creating a thin pack, which allows objects to be made into a
delta against another object that is not in the resulting pack but
is known to be present on the receiving end, the code learned to
take advantage of the reachability bitmap; this allows the server
to send a delta against a base beyond the "boundary" commit.

* jk/pack-delta-reuse-with-bitmap:
  pack-objects: reuse on-disk deltas for thin "have" objects
  pack-bitmap: save "have" bitmap from walk
  t/perf: add perf tests for fetches from a bitmapped server
  t/perf: add infrastructure for measuring sizes
  t/perf: factor out percent calculations
  t/perf: factor boilerplate out of test_perf

The unpack_trees() API used in checking out a branch and merging
walks one or more trees along with the index.  When the cache-tree
in the index tells us that we are walking a tree whose flattened
contents is known (i.e. matches a span in the index), as linearly
scanning a span in the index is much more efficient than having to
open tree objects recursively and listing their entries, the walk
can be optimized, which is done in this topic.

* nd/unpack-trees-with-cache-tree:
  Document update for nd/unpack-trees-with-cache-tree
  cache-tree: verify valid cache-tree in the test suite
  unpack-trees: add missing cache invalidation
  unpack-trees: reuse (still valid) cache-tree from src_index
  unpack-trees: reduce malloc in cache-tree walk
  unpack-trees: optimize walking same trees with cache-tree
  unpack-trees: add performance tracing
  trace.h: support nested performance tracing

The code for computing history reachability has been shuffled,
obtained a bunch of new tests to cover them, and then being
improved.

* ds/reachable:
  commit-reach: correct accidental #include of C file
  commit-reach: use can_all_from_reach
  commit-reach: make can_all_from_reach... linear
  commit-reach: replace ref_newer logic
  test-reach: test commit_contains
  test-reach: test can_all_from_reach_with_flags
  test-reach: test reduce_heads
  test-reach: test get_merge_bases_many
  test-reach: test is_descendant_of
  test-reach: test in_merge_bases
  test-reach: create new test tool for ref_newer
  commit-reach: move can_all_from_reach_with_flags
  upload-pack: generalize commit date cutoff
  upload-pack: refactor ok_to_give_up()
  upload-pack: make reachable() more generic
  commit-reach: move commit_contains from ref-filter
  commit-reach: move ref_newer from remote.c
  commit.h: remove method declarations
  commit-reach: move walk methods from commit.c

"git submodule update" is getting rewritten piece-by-piece into C.

* sb/submodule-update-in-c:
  submodule--helper: introduce new update-module-mode helper
  submodule--helper: replace connect-gitdir-workingtree by ensure-core-worktree
  builtin/submodule--helper: factor out method to update a single submodule
  builtin/submodule--helper: store update_clone information in a struct
  builtin/submodule--helper: factor out submodule updating
  git-submodule.sh: rename unused variables
  git-submodule.sh: align error reporting for update mode to use path

Fixes to "git rerere" corner cases, especially when conflict
markers cannot be parsed in the file.

* tg/rerere:
  rerere: recalculate conflict ID when unresolved conflict is committed
  rerere: teach rerere to handle nested conflicts
  rerere: return strbuf from handle path
  rerere: factor out handle_conflict function
  rerere: only return whether a path has conflicts or not
  rerere: fix crash with files rerere can't handle
  rerere: add documentation for conflict normalization
  rerere: mark strings for translation
  rerere: wrap paths in output in sq
  rerere: lowercase error messages
  rerere: unify error messages when read_cache fails

When there are too many packfiles in a repository (which is not
recommended), looking up an object in these would require
consulting many pack .idx files; a new mechanism to have a single
file that consolidates all of these .idx files is introduced.

* ds/multi-pack-index: (32 commits)
  pack-objects: consider packs in multi-pack-index
  midx: test a few commands that use get_all_packs
  treewide: use get_all_packs
  packfile: add all_packs list
  midx: fix bug that skips midx with alternates
  midx: stop reporting garbage
  midx: mark bad packed objects
  multi-pack-index: store local property
  multi-pack-index: provide more helpful usage info
  midx: clear midx on repack
  packfile: skip loading index if in multi-pack-index
  midx: prevent duplicate packfile loads
  midx: use midx in approximate_object_count
  midx: use existing midx when writing new one
  midx: use midx in abbreviation calculations
  midx: read objects from multi-pack-index
  config: create core.multiPackIndex setting
  midx: write object offsets
  midx: write object id fanout chunk
  midx: write object ids in a chunk
  ...

Updated plan to repurpose the "-l" option to "git branch".

* jk/branch-l-1-repurpose:
  doc/git-branch: remove obsolete "-l" references
  branch: make "-l" a synonym for "--list"

Developer aid.

* tg/conflict-marker-size:
  .gitattributes: add conflict-marker-size for relevant files

Build tweak.

* ts/doc-build-manpage-xsl-quietly:
  Documentation/Makefile: make manpage-base-url.xsl generation quieter