t5303: drop "count=1" from corruption dd

This test corrupts pack objects by using "dd" with a seek
command. It passes "count=1 bs=1" to munge just a single
byte. However, the test added in commit b3118bdc wants to
munge two bytes, and the second byte of corruption is
silently ignored.

This turned out not to impact the test, however. The idea
was to reduce the "size of this entry" part of the header so
that zlib runs out of input bytes while inflating the entry.
That header is two bytes long, and the test reduced the
value of both bytes; since we experience the problem if we
are off by even 1 byte, it is sufficient to munge only the
first one.

Even though the test would have worked with only a single
byte munged, and we could simply tweak the test to use a
single byte, it makes sense to lift this 1-byte restriction
from do_corrupt_object. It will allow future tests that do
need to change multiple bytes to do so.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
unpack_entry: do not die when we fail to apply a delta

When we try to load an object from disk and fail, our
general strategy is to see if we can get it from somewhere
else (e.g., a loose object). That lets users fix corruption
problems by copying known-good versions of objects into the
object database.

We already handle the case where we were not able to read
the delta from disk. However, when we find that the delta we
read does not apply, we simply die.  This case is harder to
trigger, as corruption in the delta data itself would
trigger a crc error from zlib.  However, a corruption that
pointed us at the wrong delta base might cause it.

We can do the same "fail and try to find the object
elsewhere" trick instead of dying. This not only gives us a
chance to recover, but also puts us on code paths that will
alert the user to the problem (with the current message,
they do not even know which sha1 caused the problem).

Note that unlike some other pack corruptions, we do not
recover automatically from this case when doing a repack.
There is nothing apparently wrong with the delta, as it
points to a valid, accessible object, and we realize the
error only when the resulting size does not match up. And in
theory, one could even have a case where the corrupted size
is the same, and the problem would only be noticed by
recomputing the sha1.

We can get around this by recomputing the deltas with
--no-reuse-delta, which our test does (and this is probably
good advice for anyone recovering from pack corruption).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'nd/make-wildmatch-default' into jch

* nd/make-wildmatch-default:
  Makefile: promote wildmatch to be the default fnmatch implementation
Merge branch 'js/test-ln-s-add' into jch

Many tests that check the behaviour of symbolic links stored in the
index or the tree objects do not have to be skipped on a filesystem
that lack symbolic link support.

* js/test-ln-s-add:
  t4011: remove SYMLINKS prerequisite
  t6035: use test_ln_s_add to remove SYMLINKS prerequisite
  t3509, t4023, t4114: use test_ln_s_add to remove SYMLINKS prerequisite
  t3100: use test_ln_s_add to remove SYMLINKS prerequisite
  t3030: use test_ln_s_add to remove SYMLINKS prerequisite
  t0000: use test_ln_s_add to remove SYMLINKS prerequisite
  tests: use test_ln_s_add to remove SYMLINKS prerequisite (trivial cases)
  tests: introduce test_ln_s_add
  t3010: modernize style
  test-chmtime: Fix exit code on Windows
Merge branch 'mz/rebase-tests' into jch

* mz/rebase-tests:
  tests: move test for rebase messages from t3400 to t3406
  t3406: modernize style
  add tests for rebasing merged history
  add tests for rebasing root
  add tests for rebasing of empty commits
  add tests for rebasing with patch-equivalence present
  add simple tests of consistency across rebase types
Merge branch 'fc/makefile' into jch

Makefile simplification.

* fc/makefile:
  Makefile: use $^ to avoid listing prerequisites on the command line
  build: do not install git-remote-testgit
  build: generate and clean test scripts
Merge branch 'fc/show-non-empty-errors-in-test' into jch

* fc/show-non-empty-errors-in-test:
  test: test_must_be_empty helper
Merge branch 'nd/traces' into jch

* nd/traces:
  git.txt: document GIT_TRACE_PACKET
  core: use env variable instead of config var to turn on logging pack access
Merge branch 'rs/discard-index-discard-array' into jch

* rs/discard-index-discard-array:
  read-cache: free cache in discard_index
  read-cache: add simple performance test
Merge branch 'mm/color-auto-default' into jch

Flip the default for color.ui to 'auto', which is what many
tutorials recommend new users to do.

* mm/color-auto-default:
  make color.ui default to 'auto'
  config: refactor management of color.ui's default value
Merge branch 'rs/match-trees-refactor' into jch

Code cleanup.

* rs/match-trees-refactor:
  match-trees: factor out fill_tree_desc_strict
Merge branch 'rs/logical-vs-binary-or' into jch

Code cleanup.

* rs/logical-vs-binary-or:
  use logical OR (||) instead of binary OR (|) in logical context
Merge branch 'jk/commit-info-slab' into jch

Allow adding custom information to commit objects in order to
represent unbound number of flag bits etc.

* jk/commit-info-slab:
  commit-slab: introduce a macro to define a slab for new type
  commit-slab: avoid large realloc
  commit: allow associating auxiliary info on-demand
Merge branch 'jc/topo-author-date-sort' into jch

"git log" learned the "--author-date-order" option, with which the
output is topologically sorted and commits in parallel histories
are shown intermixed together based on the author timestamp.

* jc/topo-author-date-sort:
  log: --author-date-order
  sort-in-topological-order: use prio-queue
  prio-queue: priority queue of pointers to structs
  toposort: rename "lifo" field

# Conflicts:
# 	.gitignore
# 	Makefile
# 	revision.c
Merge branch 'cm/remote-mediawiki' into jch

* cm/remote-mediawiki:
  git-remote-mediawiki: display message when launched directly

# Conflicts:
# 	contrib/mw-to-git/git-remote-mediawiki.perl
Merge branch 'jg/status-config' into jch

* jg/status-config:
  status: introduce status.branch to enable --branch by default
  status: introduce status.short to enable --short by default
### match next
Merge branch 'jx/clean-interactive' into jch

* jx/clean-interactive:
  test: add t7301 for git-clean--interactive
  git-clean: add documentation for interactive git-clean
  git-clean: add ask each interactive action
  git-clean: add select by numbers interactive action
  git-clean: add filter by pattern interactive action
  git-clean: use a git-add-interactive compatible UI
  git-clean: add colors to interactive git-clean
  git-clean: show items of del_list in columns
  git-clean: add support for -i/--interactive
  git-clean: refactor git-clean into two phases
  Refactor write_name_quoted_relative, remove unused params
  Refactor quote_path_relative, remove unused params
  quote.c: remove path_relative, use relative_path instead
  path.c: refactor relative_path(), not only strip prefix
  test: add test cases for relative_path
Merge branch 'mh/loose-refs-race-with-pack-ref' into jch

* mh/loose-refs-race-with-pack-ref:
  resolve_ref_unsafe(): close race condition reading loose refs
  resolve_ref_unsafe(): nest reference-reading code in an infinite loop
  resolve_ref_unsafe(): handle the case of an SHA-1 within loop
  resolve_ref_unsafe(): extract function handle_missing_loose_ref()
Merge branch 'jk/add-i-custom-diff-algo' into jch

* jk/add-i-custom-diff-algo:
  add--interactive: respect diff.algorithm