This refactors `repair_worktree_after_gitdir_move()` to use the new
`write_worktree_linking_files` function. It also preserves the
relativity of the linking files; e.g., if an existing worktree used
absolute paths then the repaired paths will be absolute (and visa-versa).
`repair_worktree_after_gitdir_move()` is used to repair both sets of
worktree linking files if the `.git` directory is moved during a
re-initialization using `git init`.
This also adds a test case for reinitializing a repository that has
relative worktrees.
Signed-off-by: Caleb White <cdwhite3@pm.me>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This teaches the `worktree repair` command to respect the
`--[no-]relative-paths` CLI option and `worktree.useRelativePaths`
config setting. If an existing worktree with an absolute path is repaired
with `--relative-paths`, the links will be replaced with relative paths,
even if the original path was correct. This allows a user to covert
existing worktrees between absolute/relative as desired.
To simplify things, both linking files are written when one of the files
needs to be repaired. In some cases, this fixes the other file before it
is checked, in other cases this results in a correct file being written
with the same contents.
Signed-off-by: Caleb White <cdwhite3@pm.me>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This teaches the `worktree move` command to respect the
`--[no-]relative-paths` CLI option and `worktree.useRelativePaths`
config setting. If an existing worktree is moved with `--relative-paths`
the new path will be relative (and visa-versa).
Signed-off-by: Caleb White <cdwhite3@pm.me>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This introduces the `--[no-]relative-paths` CLI option and
`worktree.useRelativePaths` configuration setting to the `worktree add`
command. When enabled these options allow worktrees to be linked using
relative paths, enhancing portability across environments where absolute
paths may differ (e.g., containerized setups, shared network drives).
Git still creates absolute paths by default, but these options allow
users to opt-in to relative paths if desired.
The t2408 test file is removed and more comprehensive tests are
written for the various worktree operations in their own files.
Signed-off-by: Caleb White <cdwhite3@pm.me>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A new helper function, `write_worktree_linking_files()`, centralizes
the logic for computing and writing either relative or absolute
paths, based on the provided configuration. This function accepts
`strbuf` pointers to both the worktree’s `.git` link and the
repository’s `gitdir`, and then writes the appropriate path to each.
The `relativeWorktrees` extension is automatically set when a worktree
is linked with relative paths.
Signed-off-by: Caleb White <cdwhite3@pm.me>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The previous round[1] was merged a bit early before reviewer feedback
could be applied. This correctly indents a code block and updates the
`infer_backlink` function to return `-1` on failure and strbuf.len on
success.
[1]: https://lore.kernel.org/git/20241007-wt_relative_paths-v3-0-622cf18c45eb@pm.me
Signed-off-by: Caleb White <cdwhite3@pm.me>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A new extension, `relativeWorktrees`, is added to indicate that at least
one worktree in the repository has been linked with relative paths.
This ensures older Git versions do not attempt to automatically prune
worktrees with relative paths, as they would not not recognize the
paths as being valid.
Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Caleb White <cdwhite3@pm.me>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When reinitializing a repository, Git does not account for extensions
other than `objectformat` and `refstorage` when determining the
repository version. This can lead to a repository being downgraded to
version 0 if extensions are set, causing Git future operations to fail.
This patch teaches Git to check if other extensions are defined in the
config to ensure that the repository version is set correctly.
Signed-off-by: Caleb White <cdwhite3@pm.me>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It is more efficient to have something in the coding guidelines
document to point at, when we want to review and comment on a new
message in the codebase to make sure it "fits" in the set of
existing messages.
Let's write down established best practice we are aware of.
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When fetching directly from a bundle, fsck message severity
configuration is not propagated to the underlying git-index-pack(1). It
is only capable of enabling or disabling fsck checks entirely. This does
not align with the fsck behavior for fetches through git-fetch-pack(1).
Use the fsck config parsing from fetch-pack to populate fsck message
severity configuration and wire it through to `unbundle()` to enable the
same fsck verification as done through fetch-pack.
Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When `fetch_pack_config()` is invoked, fetch-pack configuration is
parsed from the config. As part of this operation, fsck message severity
configuration is assigned to the `fsck_msg_types` global variable. This
is optionally used to configure the downstream git-index-pack(1) when
the `--strict` option is specified.
The same parsed fsck message severity configuration is also needed
outside of fetch-pack. Instead of exposing/relying on the existing
global state, split out the fsck config parsing logic into
`fetch_pack_fsck_config()` and expose it. In a subsequent commit, this
is used to provide fsck configuration when invoking `unbundle()`.
For `fetch_pack_fsck_config()` to discern between errors and unhandled
config variables, the return code when `git_config_path()` errors is
changed to a different value also indicating success. This frees up the
previous return code to now indicate the provided config variable
was unhandled. The behavior remains functionally the same.
Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If the `VERIFY_BUNDLE_FLAG` is set during `unbundle()`, the
git-index-pack(1) spawned is configured with the `--fsck-options` flag
to perform fsck verification. With this flag enabled, there is not a way
to configure fsck message severity though.
Extend the `unbundle_opts` type to store fsck message severity
configuration and update `unbundle()` to conditionally append it to the
`--fsck-objects` flag if provided. This enables `unbundle()` call sites
to support optionally setting the severity for specific fsck messages.
Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When `unbundle()` is invoked, fsck verification may be configured by
passing the `VERIFY_BUNDLE_FSCK` flag. This mechanism allows fsck checks
on the bundle to be enabled or disabled entirely. To facilitate more
fine-grained fsck configuration, additional context must be provided to
`unbundle()`.
Introduce the `unbundle_opts` type, which wraps the existing
`verify_bundle_flags`, to facilitate future extension of `unbundle()`
configuration. Also update `unbundle()` and its call sites to accept
this new options type instead of the flags directly. The end behavior is
functionally the same, but allows for the set of configurable options to
be extended. This is leveraged in a subsequent commit to enable fsck
message severity configuration.
Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The ref-transaction hook triggered for reflog updates, which has
been corrected.
* kn/ref-transaction-hook-with-reflog:
refs: don't invoke reference-transaction hook for reflogs
We now ensure "index-pack" is used with the "--promisor" option
only during a "git fetch".
* jt/index-pack-allow-promisor-only-while-fetching:
index-pack: teach --promisor to forbid pack name
"git fast-import" can be tricked into a replace ref that maps an
object to itself, which is a useless thing to do.
* en/fast-import-avoid-self-replace:
fast-import: avoid making replace refs point to themselves
GCC 15 compatibility updates.
* jk/gcc15:
object-file: inline empty tree and blob literals
object-file: treat cached_object values as const
object-file: drop oid field from find_cached_object() return value
object-file: move empty_tree struct into find_cached_object()
object-file: drop confusing oid initializer of empty_tree struct
object-file: prefer array-of-bytes initializer for hash literals
Fix for clar unit tests to support CMake build.
* ps/clar-build-improvement:
Makefile: let clar header targets depend on their scripts
cmake: use verbatim arguments when invoking clar commands
cmake: use SH_EXE to execute clar scripts
t/unit-tests: convert "clar-generate.awk" into a shell script
Documentation for "git bundle" saw improvements to more prominently
call out the use of '--all' when creating bundles.
* kh/bundle-docs:
Documentation/git-bundle.txt: discuss naïve backups
Documentation/git-bundle.txt: mention --all in spec. refs
Documentation/git-bundle.txt: remove old `--all` example
Documentation/git-bundle.txt: mention full backup example
In cfd971520e (refs: keep track of unresolved reference value in
iterators, 2024-08-09), we added a new field "referent" into the "struct
ref" structure. In order to free the "referent", we unconditionally
freed the "referent" by simply adding a "free" statement.
However, this is a bad usage. Because when ref entry is either directory
or loose ref, we will always execute the following statement:
free(entry->u.value.referent);
This does not make sense. We should never access the "entry->u.value"
field when "entry" is a directory. However, the change obviously doesn't
break the tests. Let's analysis why.
The anonymous union in the "ref_entry" has two members: one is "struct
ref_value", another is "struct ref_dir". On a 64-bit machine, the size
of "struct ref_dir" is 32 bytes, which is smaller than the 48-byte size
of "struct ref_value". And the offset of "referent" field in "struct
ref_value" is 40 bytes. So, whenever we create a new "ref_entry" for a
directory, we will leave the offset from 40 bytes to 48 bytes untouched,
which means the value for this memory is zero (NULL). It's OK to free a
NULL pointer, but this is merely a coincidence of memory layout.
To fix this issue, we now ensure that "free(entry->u.value.referent)" is
only called when "entry->flag" indicates that it represents a loose
reference and not a directory to avoid the invalid memory operation.
Signed-off-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When reading references the reftable backend has to:
1. Create a new ref iterator.
2. Seek the iterator to the record we're searching for.
3. Read the record.
We cannot really avoid the last two steps, but re-creating the iterator
every single time we want to read a reference is kind of expensive and a
waste of resources. We couldn't help it in the past though because it
was not possible to reuse iterators. But starting with 5bf96e0c39
(reftable/generic: move seeking of records into the iterator,
2024-05-13) we have split up the iterator lifecycle such that creating
the iterator and seeking are two different concerns.
Refactor the code such that we cache iterators in the reftable backend.
This cache is invalidated whenever the respective stack is reloaded such
that we know to recreate the iterator in that case. This leads to a
sizeable speedup when creating many refs, which requires a lot of random
reference reads:
Benchmark 1: update-ref: create many refs (refcount = 100000, revision = master)
Time (mean ± σ): 1.793 s ± 0.010 s [User: 0.954 s, System: 0.835 s]
Range (min … max): 1.781 s … 1.811 s 10 runs
Benchmark 2: update-ref: create many refs (refcount = 100000, revision = HEAD)
Time (mean ± σ): 1.680 s ± 0.013 s [User: 0.846 s, System: 0.831 s]
Range (min … max): 1.664 s … 1.702 s 10 runs
Summary
update-ref: create many refs (refcount = 100000, revision = HEAD) ran
1.07 ± 0.01 times faster than update-ref: create many refs (refcount = 100000, revision = master)
While 7% is not a huge win, you have to consider that the benchmark is
_writing_ data, so _reading_ references is only one part of what we do.
Flame graphs show that we spend around 40% of our time reading refs, so
the speedup when reading refs is approximately ~2.5x that. I could not
find better benchmarks where we perform a lot of random ref reads.
You can also see a sizeable impact on memory usage when creating 100k
references. Before this change:
HEAP SUMMARY:
in use at exit: 19,112,538 bytes in 200,170 blocks
total heap usage: 8,400,426 allocs, 8,200,256 frees, 454,367,048 bytes allocated
After this change:
HEAP SUMMARY:
in use at exit: 674,416 bytes in 169 blocks
total heap usage: 7,929,872 allocs, 7,929,703 frees, 281,509,985 bytes allocated
As an additional factor, this refactoring opens up the possibility for
more performance optimizations in how we re-seek iterators. Any change
that allows us to optimize re-seeking by e.g. reusing data structures
would thus also directly speed up random reads.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 5bf96e0c39 (reftable/generic: move seeking of records into the
iterator, 2024-05-13) we have refactored the reftable codebase such that
iterators can be initialized once and then re-seeked multiple times.
This feature is used by 1869525066 (refs/reftable: wire up support for
exclude patterns, 2024-09-16) in order to skip records based on exclude
patterns provided by the caller.
The logic to re-seek the merged iterator is insufficient though because
we don't drain the priority queue on a re-seek. This means that the
queue may contain stale entries and thus reading the next record in the
queue will return the wrong entry. While this is an obvious bug, it is
harmless in the context of above exclude patterns:
- If the queue contained stale entries that match the pattern then the
caller would already know to filter out such refs. This is because
our codebase is prepared to handle backends that don't have a way to
efficiently implement exclude patterns.
- If the queue contained stale entries that don't match the pattern
we'd eventually filter out any duplicates. This is because the
reftable code discards items with the same ref name and sorts any
remaining entries properly.
So things happen to work in this context regardless of the bug, and
there is no other use case yet where we re-seek iterators. We're about
to introduce a caching mechanism though where iterators are reused by
the reftable backend, and that will expose the bug.
Fix the issue by draining the priority queue when seeking and add a
testcase that surfaces the issue.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Reftable stacks are reloaded in two cases:
- When calling `reftable_stack_reload()`, if the stat-cache tells us
that the stack has been modified.
- When committing a reftable addition.
While callers can figure out the second case, they do not have a
mechanism to figure out whether `reftable_stack_reload()` led to an
actual reload of the on-disk data. All they can do is thus to assume
that data is always being reloaded in that case.
Improve the situation by introducing a new `on_reload()` callback to the
reftable options. If provided, the function will be invoked every time
the stack has indeed been reloaded. This allows callers to invalidate
data that depends on the current stack data.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Refactor the callback function that expires reflog entries in the
reftable backend to use `reftable_backend_read_ref()` instead of
accessing the reftable stack directly. This ensures that the function
will benefit from the new caching layer that we're about to introduce.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Refactor the callback function that reads symbolic references in the
reftable backend to use `reftable_backend_read_ref()` instead of
accessing the reftable stack directly. This ensures that the function
will benefit from the new caching layer that we're about to introduce.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Refactor `read_ref_without_reload()` to accept `struct reftable_backend`
as parameter instead of `struct reftable_stack`. Rename the function to
`reftable_backend_read_ref()` to clarify its scope and move it close to
other functions operating on `struct reftable_backend`.
This change allows us to implement an additional caching layer when
reading refs where we can reuse reftable iterators.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The function `read_ref_without_reload()` accepts a ref store as input
only so that we can figure out the hash function used by it. This is
duplicate information though because the reftable stack knows about its
hash function, too.
Drop the superfluous parameter to simplify the calling convention a bit.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add an accessor function that allows callers to access the hash ID of a
reftable stack. This function will be used in a subsequent commit.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When accessing a stack we almost always have to reload the stack before
reading data from it. This is mostly because Git does not have a
notification mechanism for when underlying data has been changed, and
thus we are forced to opportunistically reload the stack every single
time to account for any changes that may have happened concurrently.
Handle the reload internally in `backend_for()`. For one this forces
callsites to think about whether or not they need to reload the stack.
But second this makes the logic to access stacks more self-contained by
letting the `struct reftable_backend` manage themselves.
Update callsites where we don't reload the stack to document why we
don't. In some cases it's unclear whether it is the right thing to do in
the first place, but fixing that is outside of the scope of this patch
series.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The reftable ref store needs to keep track of multiple stacks, one for
the main worktree and an arbitrary number of stacks for worktrees. This
is done by storing pointers to `struct reftable_stack`, which we then
access directly.
Wrap the stack in a new `struct reftable_backend`. This will allow us to
attach more data to each respective stack in subsequent commits.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 9b1cb5070f (builtin: add a repository parameter for builtin
functions, 2024-09-13) the repository was passed down to all builtin
commands. This allowed the repository to be passed down to lower layers
without depending on the global `the_repository` variable.
Continue this work by also passing down the repository parameter from
the command to sub-commands. This will help pass down the repository to
other subsystems and cleanup usage of global variables like
'the_repository' and 'the_hash_algo'.
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If a user specified e.g.
M 100644 :1 ../some-file
then fast-import previously would happily create a git history where
there is a tree in the top-level directory named "..", and with a file
inside that directory named "some-file". The top-level ".." directory
causes problems. While git checkout will die with errors and fsck will
report hasDotdot problems, the user is going to have problems trying to
remove the problematic file. Simply avoid creating this bad history in
the first place.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Coverity has started to warn about a potential double-free in
`find_bisection()`. This warning is triggered because we may modify the
list head of the passed-in `commit_list` in case it is an UNINTERESTING
commit, but still call `free_commit_list()` on the original variable
that points to the now-freed head in case where `do_find_bisection()`
returns a `NULL` pointer.
As far as I can see, this double free cannot happen in practice, as
`do_find_bisection()` only returns a `NULL` pointer when it was passed a
`NULL` input. So in order to trigger the double free we would have to
call `find_bisection()` with a commit list that only consists of
UNINTERESTING commits, but I have not been able to construct a case
where that happens.
Drop the `else` branch entirely as it seems to be a no-op anyway.
Another option might be to instead call `free_commit_list()` on `list`,
which is the modified version of `commit_list` and thus wouldn't cause a
double free. But as mentioned, I couldn't come up with any case where a
passed-in non-NULL list becomes empty, so this shouldn't be necessary.
And if it ever does become necessary we'd notice anyway via the leak
sanitizer.
Interestingly enough we did not have a single test exercising this
branch: all tests pass just fine even when replacing it with a call to
`BUG()`. Add a test that exercises it.
Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* ps/leakfixes-part-10: (27 commits)
t: remove TEST_PASSES_SANITIZE_LEAK annotations
test-lib: unconditionally enable leak checking
t: remove unneeded !SANITIZE_LEAK prerequisites
t: mark some tests as leak free
t5601: work around leak sanitizer issue
git-compat-util: drop now-unused `UNLEAK()` macro
global: drop `UNLEAK()` annotation
t/helper: fix leaking commit graph in "read-graph" subcommand
builtin/branch: fix leaking sorting options
builtin/init-db: fix leaking directory paths
builtin/help: fix leaks in `check_git_cmd()`
help: fix leaking return value from `help_unknown_cmd()`
help: fix leaking `struct cmdnames`
help: refactor to not use globals for reading config
builtin/sparse-checkout: fix leaking sanitized patterns
split-index: fix memory leak in `move_cache_to_base_index()`
git: refactor builtin handling to use a `struct strvec`
git: refactor alias handling to use a `struct strvec`
strvec: introduce new `strvec_splice()` function
line-log: fix leak when rewriting commit parents
...
The rebase todo editor has commands like `fixup -c` which affects
the commit messages of the rebased commits.[1] For example:
pick hash1 <msg>
fixup hash2 <msg>
fixup -c hash3 <msg>
This says that hash2 and hash3 should be squashed into hash1 and
that hash3’s commit message should be used for the resulting commit.
So the user is presented with an editor where the two first commit
messages are commented out and the third is not. However this does
not work if `core.commentChar`/`core.commentString` is in use since
the comment char is hardcoded (#) in this `sequencer.c` function.
As a result the first commit message will not be commented out.
† 1: See 9e3cebd97c (rebase -i: add fixup [-C | -c] command,
2021-01-29)
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Co-authored-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Reported-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
`git revert --reference <commit>` leaves behind a comment in the
first line:[1]
# *** SAY WHY WE ARE REVERTING ON THE TITLE LINE ***
Meaning that the commit will just consist of the next line if the user
exits the editor directly:
This reverts commit <--format=reference commit>
But the comment char here is hardcoded (#). Which means that the
comment line will inadvertently be included in the commit message if
`core.commentChar`/`core.commentString` is in use.
† 1: See 43966ab315 (revert: optionally refer to commit in the
"reference" format, 2022-05-26)
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
`git rebase --update-ref` does not insert commands for dependent/sub-
branches which are checked out.[1] Instead it leaves a comment about
that fact. The comment char is hardcoded (#). In turn the comment
line gets interpreted as an invalid command when `core.commentChar`/
`core.commentString` is in use.
† 1: See 900b50c242 (rebase: add --update-refs option, 2022-07-19)
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Both `struct block_writer` and `struct reftable_writer` have a `buf`
member that is being reused to optimize the number of allocations.
Rename the variable to `scratch` to clarify its intend and provide a
comment explaining why it exists.
Suggested-by: Christian Couder <christian.couder@gmail.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `initial_transaction` flag is tracked as a signed integer, but we
typically pass around flags via unsigned integers. Adapt the type
accordingly.
Suggested-by: Christian Couder <christian.couder@gmail.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We have recently added a new test to t7900 that exercises whether
git-maintenance(1) fails as expected when the "schedule.lock" file
exists. The test depends on whether or not the host has the required
executables present to schedule maintenance tasks in the first place,
like systemd or launchctl -- if not, the test fails with an unrelated
error before even checking for the lock file. This fails for example in
our CI systems, where macOS images do not have launchctl available.
Fix this issue by creating a stub systemctl(1) binary and using the
systemd scheduler.
Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Even though `git help cli` recommends users to prefer using
"--option=value" over "--option value", there can be reasons why
giving them separately is a good idea. One reason is that shells do
not perform tilde expansion for `--option=~/path/name` but they
expand `--options ~/path/name` just fine.
This is not a problem for many options whose option parsing is
properly written using OPT_FILENAME(), because the value given to
OPT_FILENAME() is tilde-expanded internally by us, but some commands
take a pathname as a mere string, which needs this trick to have the
shell help us.
I think the reason we originally decided to recommend the stuck form
was because an option that takes an optional value requires you to
use it in the stuck form, and it is one less thing for users to
worry about if they get into the habit to always use the stuck form.
But we should be discouraging ourselves from adding an option with
an optional value in the first place, and we might want to weaken
the current recommendation.
In any case, let's describe this one case where it is necessary to
use the separate form, with an example.
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Caleb White