The get_sha1() family of functions takes a flags field, but
some of the flags are mutually exclusive. In particular, we
can only handle one disambiguating function, and the flags
quietly override each other. Let's instead detect these as
programming bugs.

Technically some of the flags are supersets of the others,
so treating COMMITTISH|TREEISH as just COMMITTISH is not
wrong, but it's a good sign the caller is confused. And
certainly asking for BLOB|TREE does not work.

We can do the check easily with some bit-twiddling, and as a
bonus, the bit-mask of disambiguators will come in handy in
a future patch.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

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

"git gc --aggressive" used to limit the delta-chain length to 250,
which is way too deep for gaining additional space savings and is
detrimental for runtime performance.  The limit has been reduced to
50.

* jk/reduce-gc-aggressive-depth:
  gc: default aggressive depth to 50

Even when "git pull --rebase=preserve" (and the underlying "git
rebase --preserve") can complete without creating any new commit
(i.e. fast-forwards), it still insisted on having a usable ident
information (read: user.email is set correctly), which was less
than nice.  As the underlying commands used inside "git rebase"
would fail with a more meaningful error message and advice text
when the bogus ident matters, this extra check was removed.

* jk/rebase-i-drop-ident-check:
  rebase-interactive: drop early check for valid ident

More i18n.

* va/i18n:
  i18n: update-index: mark warnings for translation
  i18n: show-branch: mark plural strings for translation
  i18n: show-branch: mark error messages for translation
  i18n: receive-pack: mark messages for translation
  notes: spell first word of error messages in lowercase
  i18n: notes: mark error messages for translation
  i18n: merge-recursive: mark verbose message for translation
  i18n: merge-recursive: mark error messages for translation
  i18n: config: mark error message for translation
  i18n: branch: mark option description for translation
  i18n: blame: mark error messages for translation

"git format-patch --base=..." feature that was recently added
showed the base commit information after "-- " e-mail signature
line, which turned out to be inconvenient.  The base information
has been moved above the signature line.

* jt/format-patch-base-info-above-sig:
  format-patch: show base info before email signature

Performance tests done via "t/perf" did not use the same set of
build configuration if the user relied on autoconf generated
configuration.

* ks/perf-build-with-autoconf:
  t/perf/run: copy config.mak.autogen & friends to build area

Code cleanup.

* mr/vcs-svn-printf-ulong:
  vcs-svn/fast_export: fix timestamp fmt specifiers

"git diff -W" output needs to extend the context backward to
include the header line of the current function and also forward to
include the body of the entire current function up to the header
line of the next one.  This process may have to merge to adjacent
hunks, but the code forgot to do so in some cases.

* rs/xdiff-merge-overlapping-hunks-for-W-context:
  xdiff: fix merging of hunks with -W context and -u context

Code cleanup.

* rs/unpack-trees-reduce-file-scope-global:
  unpack-trees: pass checkout state explicitly to check_updates()

Code cleanup.

* rs/strbuf-remove-fix:
  strbuf: use valid pointer in strbuf_remove()

Code cleanup.

* rs/pack-sort-with-llist-mergesort:
  sha1_file: use llist_mergesort() for sorting packs

Code cleanup.

* rs/checkout-some-states-are-const:
  checkout: constify parameters of checkout_stage() and checkout_merged()

There were numerous corner cases in which the configuration files
are read and used or not read at all depending on the directory a
Git command was run, leading to inconsistent behaviour.  The code
to set-up repository access at the beginning of a Git process has
been updated to fix them.

* jk/setup-sequence-update:
  t1007: factor out repeated setup
  init: reset cached config when entering new repo
  init: expand comments explaining config trickery
  config: only read .git/config from configured repos
  test-config: setup git directory
  t1302: use "git -C"
  pager: handle early config
  pager: use callbacks instead of configset
  pager: make pager_program a file-local static
  pager: stop loading git_default_config()
  pager: remove obsolete comment
  diff: always try to set up the repository
  diff: handle --no-index prefixes consistently
  diff: skip implicit no-index check when given --no-index
  patch-id: use RUN_SETUP_GENTLY
  hash-object: always try to set up the git repository

The http transport (with curl-multi option, which is the default
these days) failed to remove curl-easy handle from a curlm session,
which led to unnecessary API failures.

* ew/http-do-not-forget-to-call-curl-multi-remove-handle:
  http: always remove curl easy from curlm session on release
  http: consolidate #ifdefs for curl_multi_remove_handle
  http: warn on curl_multi_add_handle failures

Code cleanup.

* bw/pathspec-remove-unused-extern-decl:
  pathspec: remove unnecessary function prototypes

Some codepaths in "git pack-objects" were not ready to use an
existing pack bitmap; now they are and as the result they have
become faster.

* ks/pack-objects-bitmap:
  pack-objects: use reachability bitmap index when generating non-stdout pack
  pack-objects: respect --local/--honor-pack-keep/--incremental when bitmap is in use

"git log --cherry-pick" used to include merge commits as candidates
to be matched up with other commits, resulting a lot of wasted time.
The patch-id generation logic has been updated to ignore merges to
avoid the wastage.

* jk/patch-ids-no-merges:
  patch-ids: refuse to compute patch-id for merge commit
  patch-ids: turn off rename detection

Recently we updated the code to manage the in-core cache that holds
objects that have recently been used to reconstitute other objects
that are stored as deltas against them, but the update used an
incorrect API function to manage the list of these objects.  This
has been fixed.

* jk/delta-base-cache:
  add_delta_base_cache: use list_for_each_safe

"git add --chmod=+x" added recently lacked documentation, which has
been corrected.

* et/add-chmod-x:
  add: document the chmod option

Even though "git hash-objects", which is a tool to take an
on-filesystem data stream and put it into the Git object store,
allowed to perform the "outside-world-to-Git" conversions (e.g.
end-of-line conversions and application of the clean-filter), and
it had the feature on by default from very early days, its reverse
operation "git cat-file", which takes an object from the Git object
store and externalize for the consumption by the outside world,
lacked an equivalent mechanism to run the "Git-to-outside-world"
conversion.  The command learned the "--filters" option to do so.

* js/cat-file-filters:
  cat-file: support --textconv/--filters in batch mode
  cat-file --textconv/--filters: allow specifying the path separately
  cat-file: introduce the --filters option
  cat-file: fix a grammo in the man page

JGit can show a fake ref "capabilities^{}" to "git fetch" when it
does not advertise any refs, but "git fetch" was not prepared to
see such an advertisement.  When the other side disconnects without
giving any ref advertisement, we used to say "there may not be a
repository at that URL", but we may have seen other advertisement
like "shallow" and ".have" in which case we definitely know that a
repository is there.  The code to detect this case has also been
updated.

* jt/accept-capability-advertisement-when-fetching-from-void:
  connect: advertized capability is not a ref
  connect: tighten check for unexpected early hang up
  tests: move test_lazy_prereq JGIT to test-lib.sh

* maint:
  Start preparing for 2.10.1

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

Code cleanup.

* sb/diff-cleanup:
  diff: remove dead code
  diff: omit found pointer from emit_callback
  diff.c: use diff_options directly

Message cleanup.

* ah/misc-message-fixes:
  unpack-trees: do not capitalize "working"
  git-merge-octopus: do not capitalize "octopus"
  git-rebase--interactive: fix English grammar
  cat-file: put spaces around pipes in usage string
  am: put spaces around pipe in usage string

Message cleanup.

* sb/transport-report-missing-submodule-on-stderr:
  transport: report missing submodule pushes consistently on stderr

Code cleanup.

* sb/xdiff-remove-unused-static-decl:
  xdiff: remove unneeded declarations

Test fix.

* js/t9903-chaining:
  t9903: fix broken && chain

Code cleanup.

* rs/hex2chr:
  introduce hex2chr() for converting two hexadecimal digits to a character

Code cleanup.

* rs/compat-strdup:
  compat: move strdup(3) replacement to its own file

Compilation fix.

* jk/squelch-false-warning-from-gcc-o3:
  color_parse_mem: initialize "struct color" temporary
  error_errno: use constant return similar to error()

Update a few tests that used to use GIT_CURL_VERBOSE to use the
newer GIT_TRACE_CURL.

* ep/use-git-trace-curl-in-tests:
  t5551-http-fetch-smart.sh: use the GIT_TRACE_CURL environment var
  t5550-http-fetch-dumb.sh: use the GIT_TRACE_CURL environment var
  test-lib.sh: preserve GIT_TRACE_CURL from the environment
  t5541-http-push-smart.sh: use the GIT_TRACE_CURL environment var

A test spawned a short-lived background process, which sometimes
prevented the test directory from getting removed at the end of the
script on some platforms.

* js/t6026-clean-up:
  t6026-merge-attr: clean up background process at end of test case

"git symbolic-ref -d HEAD" happily removes the symbolic ref, but
the resulting repository becomes an invalid one.  Teach the command
to forbid removal of HEAD.

* jc/forbid-symbolic-ref-d-HEAD:
  symbolic-ref -d: do not allow removal of HEAD

Having a submodule whose ".git" repository is somehow corrupt
caused a few commands that recurse into submodules loop forever.

* jc/submodule-anchor-git-dir:
  submodule: avoid auto-discovery in prepare_submodule_repo_env()

The test framework left the number of tests and success/failure
count in the t/test-results directory, keyed by the name of the
test script plus the process ID.  The latter however turned out not
to serve any useful purpose.  The process ID part of the filename
has been removed.

* jk/test-lib-drop-pid-from-results:
  test-lib: drop PID from test-results/*.count

"diff-highlight" script (in contrib/) learned to work better with
"git log -p --graph" output.

* bh/diff-highlight-graph:
  diff-highlight: avoid highlighting combined diffs
  diff-highlight: add multi-byte tests
  diff-highlight: ignore test cruft
  diff-highlight: add support for --graph output
  diff-highlight: add failing test for handling --graph output
  diff-highlight: add some tests

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

This round they are somewhat bigger topics.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>