merge(third_party/git): Merge squashed git subtree at v2.23.0 r/373

Merge commit '1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5' as 'third_party/git'

1 files changed, 569 insertions, 0 deletions

diff --git a/third_party/git/Documentation/SubmittingPatches b/third_party/git/Documentation/SubmittingPatches
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+Submitting Patches
+==================
+
+== Guidelines
+
+Here are some guidelines for people who want to contribute their code
+to this software.
+
+[[base-branch]]
+=== Decide what to base your work on.
+
+In general, always base your work on the oldest branch that your
+change is relevant to.
+
+* A bugfix should be based on `maint` in general. If the bug is not
+  present in `maint`, base it on `master`. For a bug that's not yet
+  in `master`, find the topic that introduces the regression, and
+  base your work on the tip of the topic.
+
+* A new feature should be based on `master` in general. If the new
+  feature depends on a topic that is in `pu`, but not in `master`,
+  base your work on the tip of that topic.
+
+* Corrections and enhancements to a topic not yet in `master` should
+  be based on the tip of that topic. If the topic has not been merged
+  to `next`, it's alright to add a note to squash minor corrections
+  into the series.
+
+* In the exceptional case that a new feature depends on several topics
+  not in `master`, start working on `next` or `pu` privately and send
+  out patches for discussion. Before the final merge, you may have to
+  wait until some of the dependent topics graduate to `master`, and
+  rebase your work.
+
+* Some parts of the system have dedicated maintainers with their own
+  repositories (see the section "Subsystems" below).  Changes to
+  these parts should be based on their trees.
+
+To find the tip of a topic branch, run `git log --first-parent
+master..pu` and look for the merge commit. The second parent of this
+commit is the tip of the topic branch.
+
+[[separate-commits]]
+=== Make separate commits for logically separate changes.
+
+Unless your patch is really trivial, you should not be sending
+out a patch that was generated between your working tree and
+your commit head.  Instead, always make a commit with complete
+commit message and generate a series of patches from your
+repository.  It is a good discipline.
+
+Give an explanation for the change(s) that is detailed enough so
+that people can judge if it is good thing to do, without reading
+the actual patch text to determine how well the code does what
+the explanation promises to do.
+
+If your description starts to get too long, that's a sign that you
+probably need to split up your commit to finer grained pieces.
+That being said, patches which plainly describe the things that
+help reviewers check the patch, and future maintainers understand
+the code, are the most beautiful patches.  Descriptions that summarize
+the point in the subject well, and describe the motivation for the
+change, the approach taken by the change, and if relevant how this
+differs substantially from the prior version, are all good things
+to have.
+
+Make sure that you have tests for the bug you are fixing.  See
+`t/README` for guidance.
+
+[[tests]]
+When adding a new feature, make sure that you have new tests to show
+the feature triggers the new behavior when it should, and to show the
+feature does not trigger when it shouldn't.  After any code change, make
+sure that the entire test suite passes.
+
+If you have an account at GitHub (and you can get one for free to work
+on open source projects), you can use their Travis CI integration to
+test your changes on Linux, Mac (and hopefully soon Windows).  See
+GitHub-Travis CI hints section for details.
+
+Do not forget to update the documentation to describe the updated
+behavior and make sure that the resulting documentation set formats
+well (try the Documentation/doc-diff script).
+
+We currently have a liberal mixture of US and UK English norms for
+spelling and grammar, which is somewhat unfortunate.  A huge patch that
+touches the files all over the place only to correct the inconsistency
+is not welcome, though.  Potential clashes with other changes that can
+result from such a patch are not worth it.  We prefer to gradually
+reconcile the inconsistencies in favor of US English, with small and
+easily digestible patches, as a side effect of doing some other real
+work in the vicinity (e.g. rewriting a paragraph for clarity, while
+turning en_UK spelling to en_US).  Obvious typographical fixes are much
+more welcomed ("teh -> "the"), preferably submitted as independent
+patches separate from other documentation changes.
+
+[[whitespace-check]]
+Oh, another thing.  We are picky about whitespaces.  Make sure your
+changes do not trigger errors with the sample pre-commit hook shipped
+in `templates/hooks--pre-commit`.  To help ensure this does not happen,
+run `git diff --check` on your changes before you commit.
+
+[[describe-changes]]
+=== Describe your changes well.
+
+The first line of the commit message should be a short description (50
+characters is the soft limit, see DISCUSSION in linkgit:git-commit[1]),
+and should skip the full stop.  It is also conventional in most cases to
+prefix the first line with "area: " where the area is a filename or
+identifier for the general area of the code being modified, e.g.
+
+* doc: clarify distinction between sign-off and pgp-signing
+* githooks.txt: improve the intro section
+
+If in doubt which identifier to use, run `git log --no-merges` on the
+files you are modifying to see the current conventions.
+
+[[summary-section]]
+It's customary to start the remainder of the first line after "area: "
+with a lower-case letter. E.g. "doc: clarify...", not "doc:
+Clarify...", or "githooks.txt: improve...", not "githooks.txt:
+Improve...".
+
+[[meaningful-message]]
+The body should provide a meaningful commit message, which:
+
+. explains the problem the change tries to solve, i.e. what is wrong
+  with the current code without the change.
+
+. justifies the way the change solves the problem, i.e. why the
+  result with the change is better.
+
+. alternate solutions considered but discarded, if any.
+
+[[imperative-mood]]
+Describe your changes in imperative mood, e.g. "make xyzzy do frotz"
+instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy
+to do frotz", as if you are giving orders to the codebase to change
+its behavior.  Try to make sure your explanation can be understood
+without external resources. Instead of giving a URL to a mailing list
+archive, summarize the relevant points of the discussion.
+
+[[commit-reference]]
+If you want to reference a previous commit in the history of a stable
+branch, use the format "abbreviated sha1 (subject, date)",
+with the subject enclosed in a pair of double-quotes, like this:
+
+....
+	Commit f86a374 ("pack-bitmap.c: fix a memleak", 2015-03-30)
+	noticed that ...
+....
+
+The "Copy commit summary" command of gitk can be used to obtain this
+format, or this invocation of `git show`:
+
+....
+	git show -s --date=short --pretty='format:%h ("%s", %ad)' <commit>
+....
+
+[[git-tools]]
+=== Generate your patch using Git tools out of your commits.
+
+Git based diff tools generate unidiff which is the preferred format.
+
+You do not have to be afraid to use `-M` option to `git diff` or
+`git format-patch`, if your patch involves file renames.  The
+receiving end can handle them just fine.
+
+[[review-patch]]
+Please make sure your patch does not add commented out debugging code,
+or include any extra files which do not relate to what your patch
+is trying to achieve. Make sure to review
+your patch after generating it, to ensure accuracy.  Before
+sending out, please make sure it cleanly applies to the `master`
+branch head.  If you are preparing a work based on "next" branch,
+that is fine, but please mark it as such.
+
+[[send-patches]]
+=== Sending your patches.
+
+:security-ml: footnoteref:[security-ml,The Git Security mailing list: git-security@googlegroups.com]
+
+Before sending any patches, please note that patches that may be
+security relevant should be submitted privately to the Git Security
+mailing list{security-ml}, instead of the public mailing list.
+
+Learn to use format-patch and send-email if possible.  These commands
+are optimized for the workflow of sending patches, avoiding many ways
+your existing e-mail client that is optimized for "multipart/*" mime
+type e-mails to corrupt and render your patches unusable.
+
+People on the Git mailing list need to be able to read and
+comment on the changes you are submitting.  It is important for
+a developer to be able to "quote" your changes, using standard
+e-mail tools, so that they may comment on specific portions of
+your code.  For this reason, each patch should be submitted
+"inline" in a separate message.
+
+Multiple related patches should be grouped into their own e-mail
+thread to help readers find all parts of the series.  To that end,
+send them as replies to either an additional "cover letter" message
+(see below), the first patch, or the respective preceding patch.
+
+If your log message (including your name on the
+Signed-off-by line) is not writable in ASCII, make sure that
+you send off a message in the correct encoding.
+
+WARNING: Be wary of your MUAs word-wrap
+corrupting your patch.  Do not cut-n-paste your patch; you can
+lose tabs that way if you are not careful.
+
+It is a common convention to prefix your subject line with
+[PATCH].  This lets people easily distinguish patches from other
+e-mail discussions.  Use of markers in addition to PATCH within
+the brackets to describe the nature of the patch is also
+encouraged.  E.g. [RFC PATCH] (where RFC stands for "request for
+comments") is often used to indicate a patch needs further
+discussion before being accepted, [PATCH v2], [PATCH v3] etc.
+are often seen when you are sending an update to what you have
+previously sent.
+
+The `git format-patch` command follows the best current practice to
+format the body of an e-mail message.  At the beginning of the
+patch should come your commit message, ending with the
+Signed-off-by: lines, and a line that consists of three dashes,
+followed by the diffstat information and the patch itself.  If
+you are forwarding a patch from somebody else, optionally, at
+the beginning of the e-mail message just before the commit
+message starts, you can put a "From: " line to name that person.
+To change the default "[PATCH]" in the subject to "[<text>]", use
+`git format-patch --subject-prefix=<text>`.  As a shortcut, you
+can use `--rfc` instead of `--subject-prefix="RFC PATCH"`, or
+`-v <n>` instead of `--subject-prefix="PATCH v<n>"`.
+
+You often want to add additional explanation about the patch,
+other than the commit message itself.  Place such "cover letter"
+material between the three-dash line and the diffstat.  For
+patches requiring multiple iterations of review and discussion,
+an explanation of changes between each iteration can be kept in
+Git-notes and inserted automatically following the three-dash
+line via `git format-patch --notes`.
+
+[[attachment]]
+Do not attach the patch as a MIME attachment, compressed or not.
+Do not let your e-mail client send quoted-printable.  Do not let
+your e-mail client send format=flowed which would destroy
+whitespaces in your patches. Many
+popular e-mail applications will not always transmit a MIME
+attachment as plain text, making it impossible to comment on
+your code.  A MIME attachment also takes a bit more time to
+process.  This does not decrease the likelihood of your
+MIME-attached change being accepted, but it makes it more likely
+that it will be postponed.
+
+Exception:  If your mailer is mangling patches then someone may ask
+you to re-send them using MIME, that is OK.
+
+[[pgp-signature]]
+Do not PGP sign your patch. Most likely, your maintainer or other people on the
+list would not have your PGP key and would not bother obtaining it anyway.
+Your patch is not judged by who you are; a good patch from an unknown origin
+has a far better chance of being accepted than a patch from a known, respected
+origin that is done poorly or does incorrect things.
+
+If you really really really really want to do a PGP signed
+patch, format it as "multipart/signed", not a text/plain message
+that starts with `-----BEGIN PGP SIGNED MESSAGE-----`.  That is
+not a text/plain, it's something else.
+
+:security-ml-ref: footnoteref:[security-ml]
+
+As mentioned at the beginning of the section, patches that may be
+security relevant should not be submitted to the public mailing list
+mentioned below, but should instead be sent privately to the Git
+Security mailing list{security-ml-ref}.
+
+Send your patch with "To:" set to the mailing list, with "cc:" listing
+people who are involved in the area you are touching (the `git
+contacts` command in `contrib/contacts/` can help to
+identify them), to solicit comments and reviews.
+
+:current-maintainer: footnote:[The current maintainer: gitster@pobox.com]
+:git-ml: footnote:[The mailing list: git@vger.kernel.org]
+
+After the list reached a consensus that it is a good idea to apply the
+patch, re-send it with "To:" set to the maintainer{current-maintainer} and "cc:" the
+list{git-ml} for inclusion.
+
+Do not forget to add trailers such as `Acked-by:`, `Reviewed-by:` and
+`Tested-by:` lines as necessary to credit people who helped your
+patch.
+
+[[sign-off]]
+=== Certify your work by adding your "Signed-off-by: " line
+
+To improve tracking of who did what, we've borrowed the
+"sign-off" procedure from the Linux kernel project on patches
+that are being emailed around.  Although core Git is a lot
+smaller project it is a good discipline to follow it.
+
+The sign-off is a simple line at the end of the explanation for
+the patch, which certifies that you wrote it or otherwise have
+the right to pass it on as an open-source patch.  The rules are
+pretty simple: if you can certify the below D-C-O:
+
+[[dco]]
+.Developer's Certificate of Origin 1.1
+____
+By making a contribution to this project, I certify that:
+
+a. The contribution was created in whole or in part by me and I
+   have the right to submit it under the open source license
+   indicated in the file; or
+
+b. The contribution is based upon previous work that, to the best
+   of my knowledge, is covered under an appropriate open source
+   license and I have the right under that license to submit that
+   work with modifications, whether created in whole or in part
+   by me, under the same open source license (unless I am
+   permitted to submit under a different license), as indicated
+   in the file; or
+
+c. The contribution was provided directly to me by some other
+   person who certified (a), (b) or (c) and I have not modified
+   it.
+
+d. I understand and agree that this project and the contribution
+   are public and that a record of the contribution (including all
+   personal information I submit with it, including my sign-off) is
+   maintained indefinitely and may be redistributed consistent with
+   this project or the open source license(s) involved.
+____
+
+then you just add a line saying
+
+....
+	Signed-off-by: Random J Developer <random@developer.example.org>
+....
+
+This line can be automatically added by Git if you run the git-commit
+command with the -s option.
+
+Notice that you can place your own Signed-off-by: line when
+forwarding somebody else's patch with the above rules for
+D-C-O.  Indeed you are encouraged to do so.  Do not forget to
+place an in-body "From: " line at the beginning to properly attribute
+the change to its true author (see (2) above).
+
+[[real-name]]
+Also notice that a real name is used in the Signed-off-by: line. Please
+don't hide your real name.
+
+[[commit-trailers]]
+If you like, you can put extra tags at the end:
+
+. `Reported-by:` is used to credit someone who found the bug that
+  the patch attempts to fix.
+. `Acked-by:` says that the person who is more familiar with the area
+  the patch attempts to modify liked the patch.
+. `Reviewed-by:`, unlike the other tags, can only be offered by the
+  reviewer and means that she is completely satisfied that the patch
+  is ready for application.  It is usually offered only after a
+  detailed review.
+. `Tested-by:` is used to indicate that the person applied the patch
+  and found it to have the desired effect.
+
+You can also create your own tag or use one that's in common usage
+such as "Thanks-to:", "Based-on-patch-by:", or "Mentored-by:".
+
+== Subsystems with dedicated maintainers
+
+Some parts of the system have dedicated maintainers with their own
+repositories.
+
+- `git-gui/` comes from git-gui project, maintained by Pat Thoyts:
+
+	git://repo.or.cz/git-gui.git
+
+- `gitk-git/` comes from Paul Mackerras's gitk project:
+
+	git://ozlabs.org/~paulus/gitk
+
+- `po/` comes from the localization coordinator, Jiang Xin:
+
+	https://github.com/git-l10n/git-po/
+
+Patches to these parts should be based on their trees.
+
+[[patch-flow]]
+== An ideal patch flow
+
+Here is an ideal patch flow for this project the current maintainer
+suggests to the contributors:
+
+. You come up with an itch.  You code it up.
+
+. Send it to the list and cc people who may need to know about
+  the change.
++
+The people who may need to know are the ones whose code you
+are butchering.  These people happen to be the ones who are
+most likely to be knowledgeable enough to help you, but
+they have no obligation to help you (i.e. you ask for help,
+don't demand).  +git log -p {litdd} _$area_you_are_modifying_+ would
+help you find out who they are.
+
+. You get comments and suggestions for improvements.  You may
+  even get them in an "on top of your change" patch form.
+
+. Polish, refine, and re-send to the list and the people who
+  spend their time to improve your patch.  Go back to step (2).
+
+. The list forms consensus that the last round of your patch is
+  good.  Send it to the maintainer and cc the list.
+
+. A topic branch is created with the patch and is merged to `next`,
+  and cooked further and eventually graduates to `master`.
+
+In any time between the (2)-(3) cycle, the maintainer may pick it up
+from the list and queue it to `pu`, in order to make it easier for
+people play with it without having to pick up and apply the patch to
+their trees themselves.
+
+[[patch-status]]
+== Know the status of your patch after submission
+
+* You can use Git itself to find out when your patch is merged in
+  master. `git pull --rebase` will automatically skip already-applied
+  patches, and will let you know. This works only if you rebase on top
+  of the branch in which your patch has been merged (i.e. it will not
+  tell you if your patch is merged in pu if you rebase on top of
+  master).
+
+* Read the Git mailing list, the maintainer regularly posts messages
+  entitled "What's cooking in git.git" and "What's in git.git" giving
+  the status of various proposed changes.
+
+[[travis]]
+== GitHub-Travis CI hints
+
+With an account at GitHub (you can get one for free to work on open
+source projects), you can use Travis CI to test your changes on Linux,
+Mac (and hopefully soon Windows).  You can find a successful example
+test build here: https://travis-ci.org/git/git/builds/120473209
+
+Follow these steps for the initial setup:
+
+. Fork https://github.com/git/git to your GitHub account.
+  You can find detailed instructions how to fork here:
+  https://help.github.com/articles/fork-a-repo/
+
+. Open the Travis CI website: https://travis-ci.org
+
+. Press the "Sign in with GitHub" button.
+
+. Grant Travis CI permissions to access your GitHub account.
+  You can find more information about the required permissions here:
+  https://docs.travis-ci.com/user/github-oauth-scopes
+
+. Open your Travis CI profile page: https://travis-ci.org/profile
+
+. Enable Travis CI builds for your Git fork.
+
+After the initial setup, Travis CI will run whenever you push new changes
+to your fork of Git on GitHub.  You can monitor the test state of all your
+branches here: https://travis-ci.org/__<Your GitHub handle>__/git/branches
+
+If a branch did not pass all test cases then it is marked with a red
+cross.  In that case you can click on the failing Travis CI job and
+scroll all the way down in the log.  Find the line "<-- Click here to see
+detailed test output!" and click on the triangle next to the log line
+number to expand the detailed test output.  Here is such a failing
+example: https://travis-ci.org/git/git/jobs/122676187
+
+Fix the problem and push your fix to your Git fork.  This will trigger
+a new Travis CI build to ensure all tests pass.
+
+[[mua]]
+== MUA specific hints
+
+Some of patches I receive or pick up from the list share common
+patterns of breakage.  Please make sure your MUA is set up
+properly not to corrupt whitespaces.
+
+See the DISCUSSION section of linkgit:git-format-patch[1] for hints on
+checking your patch by mailing it to yourself and applying with
+linkgit:git-am[1].
+
+While you are at it, check the resulting commit log message from
+a trial run of applying the patch.  If what is in the resulting
+commit is not exactly what you would want to see, it is very
+likely that your maintainer would end up hand editing the log
+message when he applies your patch.  Things like "Hi, this is my
+first patch.\n", if you really want to put in the patch e-mail,
+should come after the three-dash line that signals the end of the
+commit message.
+
+
+=== Pine
+
+(Johannes Schindelin)
+
+....
+I don't know how many people still use pine, but for those poor
+souls it may be good to mention that the quell-flowed-text is
+needed for recent versions.
+
+... the "no-strip-whitespace-before-send" option, too. AFAIK it
+was introduced in 4.60.
+....
+
+(Linus Torvalds)
+
+....
+And 4.58 needs at least this.
+
+diff-tree 8326dd8350be64ac7fc805f6563a1d61ad10d32c (from e886a61f76edf5410573e92e38ce22974f9c40f1)
+Author: Linus Torvalds <torvalds@g5.osdl.org>
+Date:   Mon Aug 15 17:23:51 2005 -0700
+
+    Fix pine whitespace-corruption bug
+
+    There's no excuse for unconditionally removing whitespace from
+    the pico buffers on close.
+
+diff --git a/pico/pico.c b/pico/pico.c
+--- a/pico/pico.c
++++ b/pico/pico.c
+@@ -219,7 +219,9 @@ PICO *pm;
+	    switch(pico_all_done){	/* prepare for/handle final events */
+	      case COMP_EXIT :		/* already confirmed */
+		packheader();
++#if 0
+		stripwhitespace();
++#endif
+		c |= COMP_EXIT;
+		break;
+....
+
+(Daniel Barkalow)
+
+....
+> A patch to SubmittingPatches, MUA specific help section for
+> users of Pine 4.63 would be very much appreciated.
+
+Ah, it looks like a recent version changed the default behavior to do the
+right thing, and inverted the sense of the configuration option. (Either
+that or Gentoo did it.) So you need to set the
+"no-strip-whitespace-before-send" option, unless the option you have is
+"strip-whitespace-before-send", in which case you should avoid checking
+it.
+....
+
+=== Thunderbird, KMail, GMail
+
+See the MUA-SPECIFIC HINTS section of linkgit:git-format-patch[1].
+
+=== Gnus
+
+"|" in the `*Summary*` buffer can be used to pipe the current
+message to an external program, and this is a handy way to drive
+`git am`.  However, if the message is MIME encoded, what is
+piped into the program is the representation you see in your
+`*Article*` buffer after unwrapping MIME.  This is often not what
+you would want for two reasons.  It tends to screw up non ASCII
+characters (most notably in people's names), and also
+whitespaces (fatal in patches).  Running "C-u g" to display the
+message in raw form before using "|" to run the pipe can work
+this problem around.