Rebase to Git v2.28.0-rc0

.github/CONTRIBUTING.md

@@ -16,4 +16,7 @@ If you prefer video, then [this talk](https://www.youtube.com/watch?v=Q7i_qQW__q
 might be useful to you as the presenter walks you through the contribution
 process by example.
 
+Or, you can follow the ["My First Contribution"](https://git-scm.com/docs/MyFirstContribution)
+tutorial for another example of the contribution process.
+
 Your friendly Git community!

Documentation/CodingGuidelines

@@ -489,16 +489,11 @@ For Python scripts:
 
  - We follow PEP-8 (http://www.python.org/dev/peps/pep-0008/).
 
- - As a minimum, we aim to be compatible with Python 2.6 and 2.7.
+ - As a minimum, we aim to be compatible with Python 2.7.
 
  - Where required libraries do not restrict us to Python 2, we try to
    also be compatible with Python 3.1 and later.
 
- - When you must differentiate between Unicode literals and byte string
-   literals, it is OK to use the 'b' prefix.  Even though the Python
-   documentation for version 2.6 does not mention this prefix, it has
-   been supported since version 2.6.0.
-
 Error Messages
 
  - Do not end error messages with a full stop.

Documentation/Makefile

@@ -93,6 +93,7 @@ TECH_DOCS += technical/protocol-capabilities
 TECH_DOCS += technical/protocol-common
 TECH_DOCS += technical/protocol-v2
 TECH_DOCS += technical/racy-git
+TECH_DOCS += technical/reftable
 TECH_DOCS += technical/send-pack-pipeline
 TECH_DOCS += technical/shallow
 TECH_DOCS += technical/signature-format

Documentation/MyFirstContribution.txt

@@ -1179,8 +1179,8 @@ look at the section below this one for some context.)
 [[after-approval]]
 === After Review Approval
 
-The Git project has four integration branches: `pu`, `next`, `master`, and
-`maint`. Your change will be placed into `pu` fairly early on by the maintainer
+The Git project has four integration branches: `seen`, `next`, `master`, and
+`maint`. Your change will be placed into `seen` fairly early on by the maintainer
 while it is still in the review process; from there, when it is ready for wider
 testing, it will be merged into `next`. Plenty of early testers use `next` and
 may report issues. Eventually, changes in `next` will make it to `master`,

Documentation/RelNotes/2.28.0.txt

@@ -0,0 +1,227 @@
+Git 2.28 Release Notes
+======================
+
+Updates since v2.27
+-------------------
+
+Backward compatibility notes
+
+ * "fetch.writeCommitGraph" is deemed to be still a bit too risky and
+   is no longer part of the "feature.experimental" set.
+
+ * It used to be that setting extensions.* configuration variables
+   alone, while leaving core.repositoryFormatVersion=0, made these
+   settings effective, which was a wrong thing to do.  In version 0,
+   there was no special meaning in extensions.* configuration
+   variables.  This has been corrected.  If you need these repository
+   extensions to be effective, the core.repositoryFormatVersion
+   variable needs to be updated to 1 after vetting these extensions.*
+   variables are set correctly.
+
+
+UI, Workflows & Features
+
+ * The commands in the "diff" family learned to honor "diff.relative"
+   configuration variable.
+
+ * The check in "git fsck" to ensure that the tree objects are sorted
+   still had corner cases it missed unsorted entries.
+
+ * The interface to redact sensitive information in the trace output
+   has been simplified.
+
+ * The command line completion (in contrib/) learned to complete
+   options that the "git switch" command takes.
+
+ * "git diff" used to take arguments in random and nonsense range
+   notation, e.g. "git diff A..B C", "git diff A..B C...D", etc.,
+   which has been cleaned up.
+
+ * "git diff-files" has been taught to say paths that are marked as
+   intent-to-add are new files, not modified from an empty blob.
+
+ * "git status" learned to report the status of sparse checkout.
+
+ * "git difftool" has trouble dealing with paths added to the index
+   with the intent-to-add bit.
+
+ * "git fast-export --anonymize" learned to take customized mapping to
+   allow its users to tweak its output more usable for debugging.
+
+ * The command line completion support (in contrib/) used to be
+   prepared to work with "set -u" but recent changes got a bit more
+   sloppy.  This has been corrected.
+
+
+Performance, Internal Implementation, Development Support etc.
+
+ * Code optimization for a common case.
+   (merge 8777616e4d an/merge-single-strategy-optim later to maint).
+
+ * We've adopted a convention that any on-stack structure can be
+   initialized to have zero values in all fields with "= { 0 }",
+   even when the first field happens to be a pointer, but sparse
+   complained that a null pointer should be spelled NULL for a long
+   time.  Start using -Wno-universal-initializer option to squelch
+   it (the latest sparse has it on by default).
+
+ * "git log -L..." now takes advantage of the "which paths are touched
+   by this commit?" info stored in the commit-graph system.
+
+ * As FreeBSD is not the only platform whose regexp library reports
+   a REG_ILLSEQ error when fed invalid UTF-8, add logic to detect that
+   automatically and skip the affected tests.
+
+ * "git bugreport" learns to report what shell is in use.
+
+ * Support for GIT_CURL_VERBOSE has been rewritten in terms of
+   GIT_TRACE_CURL.
+
+ * Preliminary clean-ups around refs API, plus file format
+   specification documentation for the reftable backend.
+
+ * Workaround breakage in MSVC build, where "curl-config --cflags"
+   gives settings appropriate for GCC build.
+
+ * Code clean-up of "git clean" resulted in a fix of recent
+   performance regression.
+
+ * Code clean-up in the codepath that serves "git fetch" continues.
+
+ * "git merge-base --is-ancestor" is taught to take advantage of the
+   commit graph.
+
+ * Rewrite of parts of the scripted "git submodule" Porcelain command
+   continues; this time it is "git submodule set-branch" subcommand's
+   turn.
+
+ * The "fetch/clone" protocol has been updated to allow the server to
+   instruct the clients to grab pre-packaged packfile(s) in addition
+   to the packed object data coming over the wire.
+
+ * A misdesigned strbuf_write_fd() function has been retired.
+
+ * SHA-256 migration work continues, including CVS/SVN interface.
+
+ * A few fields in "struct commit" that do not have to always be
+   present have been moved to commit slabs.
+
+ * API cleanup for get_worktrees()
+
+ * By renumbering object flag bits, "struct object" managed to lose
+   bloated inter-field padding.
+
+ * The name of the primary branch in existing repositories, and the
+   default name used for the first branch in newly created
+   repositories, is made configurable, so that we can eventually wean
+   ourselves off of the hardcoded 'master'.
+
+ * The effort to avoid using test_must_fail on non-git command continues.
+
+
+Fixes since v2.27
+-----------------
+
+ * The "--prepare-p4-only" option of "git p4" is supposed to stop
+   after replaying one changeset, but kept going (by mistake?)
+
+ * The error message from "git checkout -b foo -t bar baz" was
+   confusing.
+
+ * Some repositories in the wild have commits that record nonsense
+   committer timezone (e.g. rails.git); "git fast-import" learned an
+   option to pass these nonsense timestamps intact to allow recreating
+   existing repositories as-is.
+   (merge d42a2fb72f en/fast-import-looser-date later to maint).
+
+ * The command line completion script (in contrib/) tried to complete
+   "git stash -p" as if it were "git stash push -p", but it was too
+   aggressive and also affected "git stash show -p", which has been
+   corrected.
+   (merge fffd0cf520 vs/complete-stash-show-p-fix later to maint).
+
+ * On-the-wire protocol v2 easily falls into a deadlock between the
+   remote-curl helper and the fetch-pack process when the server side
+   prematurely throws an error and disconnects.  The communication has
+   been updated to make it more robust.
+
+ * "git checkout -p" did not handle a newly added path at all.
+   (merge 2c8bd8471a js/checkout-p-new-file later to maint).
+
+ * The code to parse "git bisect start" command line was lax in
+   validating the arguments.
+   (merge 4d9005ff5d cb/bisect-helper-parser-fix later to maint).
+
+ * Reduce memory usage during "diff --quiet" in a worktree with too
+   many stat-unmatched paths.
+   (merge d2d7fbe129 jk/diff-memuse-optim-with-stat-unmatch later to maint).
+
+ * The reflog entries for "git clone" and "git fetch" did not
+   anonymize the URL they operated on.
+   (merge 46da295a77 js/reflog-anonymize-for-clone-and-fetch later to maint).
+
+ * The behaviour of "sparse-checkout" in the state "git clone
+   --no-checkout" left was changed accidentally in 2.27, which has
+   been corrected.
+
+ * Use of negative pathspec, while collecting paths including
+   untracked ones in the working tree, was broken.
+
+ * The same worktree directory must be registered only once, but
+   "git worktree move" allowed this invariant to be violated, which
+   has been corrected.
+   (merge 810382ed37 es/worktree-duplicate-paths later to maint).
+
+ * The effect of sparse checkout settings on submodules is documented.
+   (merge e7d7c73249 en/sparse-with-submodule-doc later to maint).
+
+ * Code clean-up around "git branch" with a minor bugfix.
+   (merge dc44639904 dl/branch-cleanup later to maint).
+
+ * A branch name used in a test has been clarified to match what is
+   going on.
+   (merge 08dc26061f pb/t4014-unslave later to maint).
+
+ * An in-code comment in "git diff" has been updated.
+   (merge c592fd4c83 dl/diff-usage-comment-update later to maint).
+
+ * The documentation and some tests have been adjusted for the recent
+   renaming of "pu" branch to "seen".
+   (merge 6dca5dbf93 js/pu-to-seen later to maint).
+
+ * The code to push changes over "dumb" HTTP had a bad interaction
+   with the commit reachability code due to incorrect allocation of
+   object flag bits, which has been corrected.
+   (merge 64472d15e9 bc/http-push-flagsfix later to maint).
+
+ * "git send-email --in-reply-to=<msg>" did not use the In-Reply-To:
+   header with the value given from the command line, and let it be
+   overridden by the value on In-Reply-To: header in the messages
+   being sent out (if exists).
+   (merge f9f60d7066 ra/send-email-in-reply-to-from-command-line-wins later to maint).
+
+ * "git log -Lx,y:path --before=date" lost track of where the range
+   should be because it didn't take the changes made by the youngest
+   commits that are omitted from the output into account.
+
+ * When "fetch.writeCommitGraph" configuration is set in a shallow
+   repository and a fetch moves the shallow boundary, we wrote out
+   broken commit-graph files that do not match the reality, which has
+   been corrected.
+
+ * "git checkout" failed to catch an error from fstat() after updating
+   a path in the working tree.
+   (merge 35e6e212fd mt/entry-fstat-fallback-fix later to maint).
+
+ * Other code cleanup, docfix, build fix, etc.
+   (merge 2c31a7aa44 jx/pkt-line-doc-count-fix later to maint).
+   (merge d63ae31962 cb/t5608-cleanup later to maint).
+   (merge 788db145c7 dl/t-readme-spell-git-correctly later to maint).
+   (merge 45a87a83bb dl/python-2.7-is-the-floor-version later to maint).
+   (merge b75a219904 es/advertise-contribution-doc later to maint).
+   (merge 0c9a4f638a rs/pull-leakfix later to maint).
+   (merge d546fe2874 rs/commit-reach-leakfix later to maint).
+   (merge 087bf5409c mk/pb-pretty-email-without-domain-part-fix later to maint).
+   (merge 5f4ee57ad9 es/worktree-code-cleanup later to maint).
+   (merge 0172f7834a cc/cat-file-usage-update later to maint).
+   (merge 81de0c01cf ma/rebase-doc-typofix later to maint).

Documentation/SubmittingPatches

@@ -3,8 +3,9 @@ Submitting Patches
 
 == Guidelines
 
-Here are some guidelines for people who want to contribute their code
-to this software.
+Here are some guidelines for people who want to contribute their code to this
+software. There is also a link:MyFirstContribution.html[step-by-step tutorial]
+available which covers many of these same guidelines.
 
 [[base-branch]]
 === Decide what to base your work on.
@@ -18,7 +19,7 @@ change is relevant to.
   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`,
+  feature depends on a topic that is in `seen`, but not in `master`,
   base your work on the tip of that topic.
 
 * Corrections and enhancements to a topic not yet in `master` should
@@ -27,7 +28,7 @@ change is relevant to.
   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
+  not in `master`, start working on `next` or `seen` 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.
@@ -37,7 +38,7 @@ change is relevant 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
+master..seen` and look for the merge commit. The second parent of this
 commit is the tip of the topic branch.
 
 [[separate-commits]]
@@ -423,7 +424,7 @@ help you find out who they are.
   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
+from the list and queue it to `seen`, in order to make it easier for
 people play with it without having to pick up and apply the patch to
 their trees themselves.
 
@@ -434,7 +435,7 @@ their trees themselves.
   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
+  tell you if your patch is merged in `seen` if you rebase on top of
   master).
 
 * Read the Git mailing list, the maintainer regularly posts messages

Documentation/config/diff.txt

@@ -105,6 +105,10 @@ diff.mnemonicPrefix::
 diff.noprefix::
 	If set, 'git diff' does not show any source or destination prefix.
 
+diff.relative::
+	If set to 'true', 'git diff' does not show changes outside of the directory
+	and show pathnames relative to the current directory.
+
 diff.orderFile::
 	File indicating how to order files within a diff.
 	See the '-O' option to linkgit:git-diff[1] for details.

Documentation/config/feature.txt

@@ -15,13 +15,9 @@ feature.experimental::
 * `fetch.negotiationAlgorithm=skipping` may improve fetch negotiation times by
 skipping more commits at a time, reducing the number of round trips.
 +
-* `fetch.writeCommitGraph=true` writes a commit-graph after every `git fetch`
-command that downloads a pack-file from a remote. Using the `--split` option,
-most executions will create a very small commit-graph file on top of the
-existing commit-graph file(s). Occasionally, these files will merge and the
-write may take longer. Having an updated commit-graph file helps performance
-of many Git commands, including `git merge-base`, `git push -f`, and
-`git log --graph`.
+* `protocol.version=2` speeds up fetches from repositories with many refs by
+allowing the client to specify which refs to list before the server lists
+them.
 
 feature.manyFiles::
 	Enable config options that optimize for repos with many files in the

Documentation/config/fetch.txt

@@ -90,5 +90,4 @@ fetch.writeCommitGraph::
 	the existing commit-graph file(s). Occasionally, these files will
 	merge and the write may take longer. Having an updated commit-graph
 	file helps performance of many Git commands, including `git merge-base`,
-	`git push -f`, and `git log --graph`. Defaults to false, unless
-	`feature.experimental` is true.
+	`git push -f`, and `git log --graph`. Defaults to false.

Documentation/config/init.txt

@@ -1,3 +1,7 @@
 init.templateDir::
 	Specify the directory from which templates will be copied.
 	(See the "TEMPLATE DIRECTORY" section of linkgit:git-init[1].)
+
+init.defaultBranch::
+	Allows overriding the default branch name e.g. when initializing
+	a new repository or when cloning an empty repository.

Documentation/config/protocol.txt

@@ -48,7 +48,8 @@ protocol.version::
 	If set, clients will attempt to communicate with a server
 	using the specified protocol version.  If the server does
 	not support it, communication falls back to version 0.
-	If unset, the default is `0`.
+	If unset, the default is `0`, unless `feature.experimental`
+	is enabled, in which case the default is `2`.
 	Supported versions:
 +
 --