Now that we have Git supporting SHA-256, we'd like to make sure that we
don't regress that state. Unfortunately, it's easy to do so, so to
help, let's add code to run one of our CI jobs with SHA-256 as the
default hash. This will help us detect any problems that may occur.
We pick the linux-clang job because it's relatively fast and the
linux-gcc job already runs the testsuite twice. We want our tests to
run as fast as possible, so we wouldn't want to add a third run to the
linux-gcc job. To make sure we properly exercise the code, let's run
the tests in the default mode (SHA-1) first and then run a second time
with SHA-256. We explicitly specify SHA-1 for the first run so that if
we change the default in the future, we make sure to test both cases.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently, the SHA1 prerequisite depends on the output of git
hash-object. However, in order for that to produce sane behavior, we
must be in a repository. If we are not, the default will remain SHA-1,
and we'll produce wrong results if we're using SHA-256 for the testsuite
but the test assertion starts when we're not in a repository.
Check the environment variable we use for this purpose, leaving it to
default to SHA-1 if none is specified.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
To allow developers to run the testsuite with a different algorithm than
the default, provide an environment variable, GIT_TEST_DEFAULT_HASH, to
specify the algorithm to use. Compute the fixed constants using
test_oid. Move the constant initialization down below the point where
test-lib-functions.sh is loaded so the functions are defined.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In some tests, we have data files which are written with a particular
hash algorithm. Instead of keeping two copies of the test files, we can
keep one, and translate the value on the fly.
In order to do so, we'll need to read both the source algorithm and the
current algorithm, so add an optional flag to the test_oid helper that
lets us look up a value for a specified hash algorithm. This should
not cause any conflicts with existing tests, since key arguments to
test_oid are allowed to contains only shell identifier characters.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that we have a complete SHA-256 implementation in Git, let's enable
it so people can use it. Remove the ENABLE_SHA256 define constant
everywhere it's used. Add tests for initializing a repository with
SHA-256.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The transition plan specifies extensions.objectFormat as the indication
that we're using a given hash in a certain repo. Read this as one of
the extensions we support. If the user has specified an invalid value,
fail.
Ensure that we reject the extension if the repository format version is
0.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently we detect the hash algorithm in use by the length of the
object ID. This is inelegant and prevents us from using a different
hash algorithm that is also 256 bits in length.
Since we cannot extend the v2 format in a backward-compatible way, let's
add a v3 format, which is identical, except for the addition of
capabilities, which are prefixed by an at sign. We add "object-format"
as the only capability and reject unknown capabilities, since we do not
have a network connection and therefore cannot negotiate with the other
side.
For compatibility, default to the v2 format for SHA-1 and require v3
for SHA-256.
In t5510, always use format v3 so we can be sure we produce consistent
results across hash algorithms. Since head -n N lists the top N lines
instead of the Nth line, let's run our output through sed to normalize
it and compare it against a fixed value, which will make sure we get
exactly what we're expecting.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A recently added test in t5702 started using git verify-pack outside of
a repository. While this poses no problems with SHA-1, with SHA-256 we
implicitly rely on the setup of the repository to initialize our hash
algorithm settings.
Since we're not in a repository here, we need to provide git verify-pack
help to set things up properly. git index-pack already knows an
--object-format option, so let's accept one as well and pass it down to
our git index-pack invocation. Since we're now dynamically adjusting
the elements in argv, let's switch to using struct argv_array to manage
them. Finally, let's make t5702 pass the proper argument on down to its
git verify-pack caller.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In dd4b732df7 ("upload-pack: send part of packfile response as uri",
2020-06-10), the git http-fetch code learned how to take ac --packfile
option. This option takes an argument, which is the name of a packfile
hash, and parses it using parse_oid_hex. It does so before calling
setup_git_directory.
However, in a SHA-256 repository this fails to work, since we have not
set the hash algorithm in use and parse_oid_hex fails as a consequence.
To ensure that we can parse packfile hashes of the right length, let's
set up the git directory before we start parsing arguments.
Since we still want to allow the invocation of -h to print the help when
we're not in a repository, gracefully handle us being outside of one and
produce an error after argument parsing has finished.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
These tests try to check that we behave properly if we encounter a
repository with version 0 but an extension. This is a laudable goal,
but the test cannot work with SHA-256, since SHA-256 repositories always
have an existing extension and are never version 0.
Add a SHA1 prerequisite to these tests.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This test needs multiple object IDs that have the same first byte.
Update the pack test code to generate a suitable packed value for
SHA-256. Update the test to use this value when using SHA-256.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The Perl test script for t9700 was matching on exactly 40 hex
characters. With SHA-256, we'll have 64 hex-character object IDs.
Create a variable with a regex which matches exactly 40 or 64 hex
characters and use that to match the output. Note that both of the uses
of this can be anchored, which makes the code simpler, so do that as
well.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we use a hash algorithm other than SHA-1, it's important to
preserve the hash-related values in the config file, but this test
overwrites the config file with a new one. Ensure we copy these values
properly from the old config to the new one so that the repository can
be read if it's using SHA-256.
Note that if there is no extensions.objectFormat value set, git config
will return unsuccessfully if we try to read it; since this is not an
error for us, use test_might_fail.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This test checks for several commit object sizes to verify that objects
are encoded as expected. However, the size of a commit object differs
between SHA-1 and SHA-256, since each contains a hex representation of
the tree's object ID. Since these are root commits, compute the size of
each commit by using a constant plus the size of a single hex object ID.
In addition, use $ZERO_OID instead of a hard-coded object ID.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Instead of using a hard-coded all-zeros object ID, use $ZERO_OID.
Compute the length of the object IDs in use and use this instead of
hard-coding the constant 40.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Adjust the test so that it computes variables for object IDs instead of
using hard-coded hashes. In addition, use cut to filter out the object
IDs and verify only the information that we're really interested in.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Allow lines which start with either a 40- or 64-character hex object ID,
to allow for both SHA-1 and SHA-256.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
One assertion in this test invokes git with core.abbrev set to "40".
Since we're expecting the full hash length, use test_oid to look up the
full hash length for the hash in use.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Compute the length of an object ID instead of hard-coding 40-based
values.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Use the ZERO_OID variable to abbreviate the all-zeros object ID for
maintainability and to avoid depending on a specific size for the hash.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Adjust the test to sanitize the diffs and strip out object IDs from
them, as it does for other object IDs, since we are not interested in
the particular values used.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Use $ZERO_OID instead of hard-coding a fixed size all-zeros object ID.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Instead of using cut with hard-coded hash sizes, use cut with fields, or
where that's not possible, sed with $OID_REGEX, so that the tests are
independent of hash size.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Adjust the test so that it computes variables for object IDs instead of
using hard-coded hashes.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Adjust the test so that it computes variables for object IDs instead of
using hard-coded hashes.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Use test_oid instead of hard-coding algorithm-specific constants and
all-zero values.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Instead of using a specific invalid hard-coded object ID, look one
up from the translation table.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This test contains hard-coded invalid object IDs. Make it hash size
independent by generating invalid object IDs using the translation
tables. Add a setup target to ensure the output of test_oid_init is
checked properly.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In this test, we want to produce several blobs whose first two hex
characters are "17", since we look at this object directory as a proxy
for how many loose objects there are before we need to GC. Use
test_oid_cache to specify strings that will hash to the right values
when turned into blobs.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Instead of hard-coding a fixed length example object ID in the test,
compute one using the translation tables. Move a variable into the
setup block so that we can ensure the exit status of test_oid is
checked.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Use $OID_REGEX instead of a hard-coded regular expression.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Instead of hard-coding a constant 40, split the output of rev-list by
field.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The idea of the magic value "ac4f2ee" in this test is to make the
reworded commit `collide2` have the same shortened ID as the commit
`collide3`.
To port the same idea to the SHA-256 version of Git, we therefore need
another magic value that causes the same collision, but this time with
the SHA-256 version of the commit IDs.
In this patch, we add code guarded by `GIT_TEST_FIND_COLLIDER` to do
exactly that. Essentially, a large number of integers is appended to the
commit message "collide2" to find such a collision. To make it easier to
find such a collision, we reduce the number of digits to 4.
As the tests are no longer dependent on SHA-1, we also rename their
titles to talk about "commit IDs" instead of "SHA-1s".
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When computing the fanout length, let's use test_oid to look up the
hexadecimal size of the hash in question instead of hard-coding a value.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Use $ZERO_OID to make the test hash independent.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The bloom filter code relies on reading object IDs using parse_oid_hex.
In order to make that work with an appropriate size, we need to have
initialized the repository's hash algorithm. Since the values we're
processing depend on the repository in use, let's set up the repository
when we run the test helper.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 2.28-rc0, we corrected a bug that some repository extensions are
honored by mistake even in a version 0 repositories (these
configuration variables in extensions.* namespace were supposed to
have special meaning in repositories whose version numbers are 1 or
higher), but this was a bit too big a change.
* jn/v0-with-extensions-fix:
repository: allow repository format upgrade with extensions
Revert "check_repository_format_gently(): refuse extensions for old repositories"
Now that we officially permit repository extensions in repository
format v0, permit upgrading a repository with extensions from v0 to v1
as well.
For example, this means a repository where the user has set
"extensions.preciousObjects" can use "git fetch --filter=blob:none
origin" to upgrade the repository to use v1 and the partial clone
extension.
To avoid mistakes, continue to forbid repository format upgrades in v0
repositories with an unrecognized extension. This way, a v0 user
using a misspelled extension field gets a chance to correct the
mistake before updating to the less forgiving v1 format.
While we're here, make the error message for failure to upgrade the
repository format a bit shorter, and present it as an error, not a
warning.
Reported-by: Huan Huan Chen <huanhuanchen@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This reverts commit 14c7fa269e.
The core.repositoryFormatVersion field was introduced in ab9cb76f66
(Repository format version check., 2005-11-25), providing a welcome
bit of forward compatibility, thanks to some welcome analysis by
Martin Atukunda. The semantics are simple: a repository with
core.repositoryFormatVersion set to 0 should be comprehensible by all
Git implementations in active use; and Git implementations should
error out early instead of trying to act on Git repositories with
higher core.repositoryFormatVersion values representing new formats
that they do not understand.
A new repository format did not need to be defined until 00a09d57eb
(introduce "extensions" form of core.repositoryformatversion,
2015-06-23). This provided a finer-grained extension mechanism for
Git repositories. In a repository with core.repositoryFormatVersion
set to 1, Git implementations can act on "extensions.*" settings that
modify how a repository is interpreted. In repository format version
1, unrecognized extensions settings cause Git to error out.
What happens if a user sets an extension setting but forgets to
increase the repository format version to 1? The extension settings
were still recognized in that case; worse, unrecognized extensions
settings do *not* cause Git to error out. So combining repository
format version 0 with extensions settings produces in some sense the
worst of both worlds.
To improve that situation, since 14c7fa269e
(check_repository_format_gently(): refuse extensions for old
repositories, 2020-06-05) Git instead ignores extensions in v0 mode.
This way, v0 repositories get the historical (pre-2015) behavior and
maintain compatibility with Git implementations that do not know about
the v1 format. Unfortunately, users had been using this sort of
configuration and this behavior change came to many as a surprise:
- users of "git config --worktree" that had followed its advice
to enable extensions.worktreeConfig (without also increasing the
repository format version) would find their worktree configuration
no longer taking effect
- tools such as copybara[*] that had set extensions.partialClone in
existing repositories (without also increasing the repository format
version) would find that setting no longer taking effect
The behavior introduced in 14c7fa269e might be a good behavior if we
were traveling back in time to 2015, but we're far too late. For some
reason I thought that it was what had been originally implemented and
that it had regressed. Apologies for not doing my research when
14c7fa269e was under development.
Let's return to the behavior we've had since 2015: always act on
extensions.* settings, regardless of repository format version. While
we're here, include some tests to describe the effect on the "upgrade
repository version" code path.
[*] ca76c0b1e1
Reported-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix to the code to produce progress bar, which is new in the
upcoming release.
* tb/commit-graph-no-check-oids:
commit-graph: fix "Collecting commits from input" progress line
The code to produce progress output from "git commit-graph --write"
had a few breakages, which have been fixed.
* sg/commit-graph-progress-fix:
commit-graph: fix "Writing out commit graph" progress counter
commit-graph: fix progress of reachable commits
When an aliased command, whose output is piped to a pager by git,
gets killed by a signal, the pager got into a funny state, which
has been corrected (again).
* ta/wait-on-aliased-commands-upon-signal:
Wait for child on signal death for aliases to externals
Wait for child on signal death for aliases to builtins
To display a progress line while reading commits from standard input
and looking them up, 5b6653e523 (builtin/commit-graph.c: dereference
tags in builtin, 2020-05-13) should have added a pair of
start_delayed_progress() and stop_progress() calls around the loop
reading stdin. Alas, the stop_progress() call ended up at the wrong
place, after write_commit_graph(), which does all the commit-graph
computation and writing, and has several progress lines of its own.
Consequently, that new
Collecting commits from input: 1234
progress line is overwritten by the first progress line shown by
write_commit_graph(), and its final "done" line is shown last, after
everything is finished:
$ { sleep 3 ; git rev-list -3 HEAD ; sleep 1 ; } | ~/src/git/git commit-graph write --stdin-commits
Expanding reachable commits in commit graph: 873402, done.
Writing out commit graph in 4 passes: 100% (3493608/3493608), done.
Collecting commits from input: 3, done.
Furthermore, that stop_progress() call was added after the 'cleanup'
label, where that loop reading stdin jumps in case of an error. In
case of invalid input this then results in the "done" line shown after
the error message:
$ { sleep 3 ; git rev-list -3 HEAD ; echo junk ; } | ~/src/git/git commit-graph write --stdin-commits
error: unexpected non-hex object ID: junk
Collecting commits from input: 3, done.
Move that stop_progress() call to the right place.
While at it, drop the unnecessary 'if (progress)' condition protecting
the stop_progress() call, because that function is prepared to handle
a NULL progress struct.
Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Reviewed-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The description of `git diff` goes through several different invocations
(numbering added by me):
1. git diff [<options>] [--] [<path>...]
2. git diff [<options>] --no-index [--] <path> <path>
3. git diff [<options>] --cached [<commit>] [--] [<path>...]
4. git diff [<options>] <commit> [--] [<path>...]
5. git diff [<options>] <commit> <commit> [--] [<path>...]
6. git diff [<options>] <commit>..<commit> [--] [<path>...]
7. git diff [<options>] <commit> <commit>... <commit> [--] [<path>...]
8. git diff [<options>] <commit>...<commit> [--] [<path>...]
It then goes on to say that "all of the <commit> in the above
description, except in the last two forms that use '..' notations, can
be any <tree>". The "last two" actually refers to 6 and 8. This got out
of sync in commit b7e10b2ca2 ("Documentation: usage for diff combined
commits", 2020-06-12) which added item 7 to the mix.
As a further complication, after b7e10b2ca2 we also have some potential
confusion around "the '..' notation". The "..[.]" in items 6 and 8 are
part of the rev notation, whereas the "..." in item 7 is manpage
language for "one or more".
Move item 6 down, i.e., to between 7 and 8, to restore the ordering.
Because 6 refers to 5 ("synonymous to the previous form") we need to
tweak the language a bit.
An added bonus of this commit is that we're trying to steer users away
from `git diff <commit>..<commit>` and moving it further down probably
doesn't hurt.
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit b7e10b2ca2 ("Documentation: usage for diff combined commits",
2020-06-12) modified the synopsis by adding an optional "[<commit>...]"
to
'git diff' [<options>] <commit> <commit> [--] [<path>...]
to effectively add
'git diff' [<options>] <commit> <commit>... <commit> [--] [<path>...]
as another valid invocation. Which makes sense.
Further down, in the description, it left the existing entry for
'git diff' [<options>] <commit> <commit> [--] [<path>...]
intact and added a new entry on
'git diff' [<options>] <commit> [<commit>...] <commit> [--] [<path>...]
where it says that "[t]his form is to view the results of a merge
commit" and details how "the first listed commit must be the merge
itself". But one possible instantiation of this form is `git diff
<commit> <commit>` for which the added text doesn't really apply.
Remove the brackets so that we lose this overlap between the two
descriptions. We can still use the more compact representation in the
synopsis.
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
