Backward Compatibility Notes
----------------------------
+ * Historically, the "-m" (mainline) option can only be used for "git
+ cherry-pick" and "git revert" when working with a merge commit.
+ This version of Git no longer warns or errors out when working with
+ a single-parent commit, as long as the argument to the "-m" option
+ is 1 (i.e. it has only one parent, and the request is to pick or
+ revert relative to that first parent). Scripts that relied on the
+ behaviour may get broken with this change.
+
Updates since v2.20
-------------------
UI, Workflows & Features
+ * The "http.version" configuration variable can be used with recent
+ enough versions of cURL library to force the version of HTTP used
+ to talk when fetching and pushing.
+
+ * Small fixes and features for fast-export and fast-import, mostly on
+ the fast-export side has been made.
+
+ * "git push $there $src:$dst" rejects when $dst is not a fully
+ qualified refname and it is not clear what the end user meant. The
+ codepath has been taught to give a clearer error message, and also
+ guess where the push should go by taking the type of the pushed
+ object into account (e.g. a tag object would want to go under
+ refs/tags/).
+
+ * "git checkout [<tree-ish>] path..." learned to report the number of
+ paths that have been checked out of the index or the tree-ish,
+ which gives it the same degree of noisy-ness as the case in which
+ the command checks out a branch. "git checkout -m <pathspec>" to
+ undo conflict resolution gives a similar message.
+
+ * "git quiltimport" learned "--keep-non-patch" option.
+
+ * "git worktree remove" and "git worktree move" refused to work when
+ there is a submodule involved. This has been loosened to ignore
+ uninitialized submodules.
+
+ * "git cherry-pick -m1" was forbidden when picking a non-merge
+ commit, even though there _is_ parent number 1 for such a commit.
+ This was done to avoid mistakes back when "cherry-pick" was about
+ picking a single commit, but is no longer useful with "cherry-pick"
+ that can pick a range of commits. Now the "-m$num" option is
+ allowed when picking any commit, as long as $num names an existing
+ parent of the commit.
+
+ * Update "git multimail" from the upstream.
+
+ * "git p4" update.
+
+ * The "--format=<placeholder>" option of for-each-ref, branch and tag
+ learned to show a few more traits of objects that can be learned by
+ the object_info API.
+
+ * "git rebase -i" learned to re-execute a command given with 'exec'
+ to run after it failed the last time.
+
+ * "git diff --color-moved-ws" updates.
+
+ * Custom userformat "log --format" learned %S atom that stands for
+ the tip the traversal reached the commit from, i.e. --source.
+
+ * "git instaweb" learned to drive http.server that comes with
+ "batteries included" Python installation (both Python2 & 3).
+
+ * A new encoding UTF-16LE-BOM has been invented to force encoding to
+ UTF-16 with BOM in little endian byte order, which cannot be directly
+ generated by using iconv.
+
+ * A new date format "--date=human" that morphs its output depending
+ on how far the time is from the current time has been introduced.
+ "--date=auto:human" can be used to use this new format (or any
+ existing format) when the output is going to the pager or to the
+ terminal, and otherwise the default format.
Performance, Internal Implementation, Development Support etc.
+ * Code clean-up with optimization for the codepath that checks
+ (non-)existence of loose objects.
+
+ * More codepaths have become aware of working with in-core repository
+ instances other than the default "the_repository".
+
+ * The "strncat()" function is now among the banned functions.
+
+ * Portability updates for the HPE NonStop platform.
+
+ * Earlier we added "-Wformat-security" to developer builds, assuming
+ that "-Wall" (which includes "-Wformat" which in turn is required
+ to use "-Wformat-security") is always in effect. This is not true
+ when config.mak.autogen is in use, unfortunately. This has been
+ fixed by unconditionally adding "-Wall" to developer builds.
+
+ * The loose object cache used to optimize existence look-up has been
+ updated.
+
+ * Flaky tests can now be repeatedly run under load with the
+ "--stress" option.
+
+ * Documentation/Makefile is getting prepared for manpage
+ localization.
+
+ * "git fetch-pack" now can talk the version 2 protocol.
+
+ * sha-256 hash has been added and plumbed through the code to allow
+ building Git with the "NewHash".
+
+ * Debugging help for http transport.
+
+ * "git fetch --deepen=<more>" has been corrected to work over v2
+ protocol.
+
+ * The code to walk tree objects has been taught that we may be
+ working with object names that are not computed with SHA-1.
+
+ * The in-core repository instances are passed through more codepaths.
+
+ * Update the protocol message specification to allow only the limited
+ use of scaled quantities. This is to ensure potential compatibility
+ issues will not get out of hand.
+
+ * Micro-optimize the code that prepares commit objects to be walked
+ by "git rev-list" when the commit-graph is available.
+
+ * "git fetch" and "git upload-pack" learned to send all exchanges over
+ the sideband channel while talking the v2 protocol.
+
+ * The codepath to write out commit-graph has been optimized by
+ following the usual pattern of visiting objects in in-pack order.
+
+ * The codepath to show progress meter while writing out commit-graph
+ file has been improved.
+
+ * Cocci rules have been updated to encourage use of strbuf_addbuf().
+
+ * "git rebase --merge" has been reimplemented by reusing the internal
+ machinery used for "git rebase -i".
+
+ * More code in "git bisect" has been rewritten in C.
+
+ * Instead of going through "git-rebase--am" scriptlet to use the "am"
+ backend, the built-in version of "git rebase" learned to drive the
+ "am" backend directly.
+
+ * The assumption to work on the single "in-core index" instance has
+ been reduced from the library-ish part of the codebase.
+
+ * The test lint learned to catch non-portable "sed" options.
+
+ * "git pack-objects" learned another algorithm to compute the set of
+ objects to send, that trades the resulting packfile off to save
+ traversal cost to favor small pushes.
+
+ * The travis CI scripts have been corrected to build Git with the
+ compiler(s) of our choice.
+
+ * "git submodule update" learned to abort early when core.worktree
+ for the submodule is not set correctly to prevent spreading damage.
+
+ * Test suite has been adjusted to run on Azure Pipeline.
+
+ * Running "Documentation/doc-diff x" from anywhere other than the
+ top-level of the working tree did not show the usage string
+ correctly, which has been fixed.
+
+ * Use of the sparse tool got easier to customize from the command
+ line to help developers.
+
+ * A new target "coverage-prove" to run the coverage test under
+ "prove" has been added.
+
+ * A flakey "p4" test has been removed.
+
+ * The code and tests assume that the system supplied iconv() would
+ always use BOM in its output when asked to encode to UTF-16 (or
+ UTF-32), but apparently some implementations output big-endian
+ without BOM. A compile-time knob has been added to help such
+ systems (e.g. NonStop) to add BOM to the output to increase
+ portability.
Fixes since v2.20
-----------------
+ * Updates for corner cases in merge-recursive.
+ (merge cc4cb0902c en/merge-path-collision later to maint).
+
+ * "git checkout frotz" (without any double-dash) avoids ambiguity by
+ making sure 'frotz' cannot be interpreted as a revision and as a
+ path at the same time. This safety has been updated to check also
+ a unique remote-tracking branch 'frotz' in a remote, when dwimming
+ to create a local branch 'frotz' out of a remote-tracking branch
+ 'frotz' from a remote.
+ (merge be4908f103 nd/checkout-dwim-fix later to maint).
+
+ * Refspecs configured with "git -c var=val clone" did not propagate
+ to the resulting repository, which has been corrected.
+ (merge 7eae4a3ac4 sg/clone-initial-fetch-configuration later to maint).
+
+ * A properly configured username/email is required under
+ user.useConfigOnly in order to create commits; now "git stash"
+ (even though it creates commit objects to represent stash entries)
+ command is exempt from the requirement.
+ (merge 3bc2111fc2 sd/stash-wo-user-name later to maint).
+
+ * The http-backend CGI process did not correctly clean up the child
+ processes it spawns to run upload-pack etc. when it dies itself,
+ which has been corrected.
+ (merge 02818a98d7 mk/http-backend-kill-children-before-exit later to maint).
+
+ * "git rev-list --exclude-promisor-objects" had to take an object
+ that does not exist locally (and is lazily available) from the
+ command line without barfing, but the code dereferenced NULL.
+ (merge 4cf67869b2 md/list-lazy-objects-fix later to maint).
+
+ * The traversal over tree objects has learned to honor
+ ":(attr:label)" pathspec match, which has been implemented only for
+ enumerating paths on the filesystem.
+ (merge 5a0b97b34c nd/attr-pathspec-in-tree-walk later to maint).
+
+ * BSD port updates.
+ (merge 4e3ecbd439 cb/openbsd-allows-reading-directory later to maint).
+ (merge b6bdc2a0f5 cb/t5004-empty-tar-archive-fix later to maint).
+ (merge 82cbc8cde2 cb/test-lint-cp-a later to maint).
+
+ * Lines that begin with a certain keyword that come over the wire, as
+ well as lines that consist only of one of these keywords, ought to
+ be painted in color for easier eyeballing, but the latter was
+ broken ever since the feature was introduced in 2.19, which has
+ been corrected.
+ (merge 1f67290450 hn/highlight-sideband-keywords later to maint).
+
+ * "git log -G<regex>" looked for a hunk in the "git log -p" patch
+ output that contained a string that matches the given pattern.
+ Optimize this code to ignore binary files, which by default will
+ not show any hunk that would match any pattern (unless textconv or
+ the --text option is in effect, that is).
+ (merge e0e7cb8080 tb/log-G-binary later to maint).
+
+ * "git submodule update" ought to use a single job unless asked, but
+ by mistake used multiple jobs, which has been fixed.
+ (merge e3a9d1aca9 sb/submodule-fetchjobs-default-to-one later to maint).
+
+ * "git stripspace" should be usable outside a git repository, but
+ under the "-s" or "-c" mode, it didn't.
+ (merge 957da75802 jn/stripspace-wo-repository later to maint).
+
+ * Some of the documentation pages formatted incorrectly with
+ Asciidoctor, which have been fixed.
+ (merge b62eb1d2f4 ma/asciidoctor later to maint).
+
+ * The core.worktree setting in a submodule repository should not be
+ pointing at a directory when the submodule loses its working tree
+ (e.g. getting deinit'ed), but the code did not properly maintain
+ this invariant.
+
+ * With zsh, "git cmd path<TAB>" was completed to "git cmd path name"
+ when the completed path has a special character like SP in it,
+ without any attempt to keep "path name" a single filename. This
+ has been fixed to complete it to "git cmd path\ name" just like
+ Bash completion does.
+
+ * The test suite tried to see if it is run under bash, but the check
+ itself failed under some other implementations of shell (notably
+ under NetBSD). This has been corrected.
+ (merge 54ea72f09c sg/test-bash-version-fix later to maint).
+
+ * "git gc" and "git repack" did not close the open packfiles that
+ they found unneeded before removing them, which didn't work on a
+ platform incapable of removing an open file. This has been
+ corrected.
+ (merge 5bdece0d70 js/gc-repack-close-before-remove later to maint).
+
+ * The code to drive GIT_EXTERNAL_DIFF command relied on the string
+ returned from getenv() to be non-volatile, which is not true, that
+ has been corrected.
+ (merge 6776a84dae kg/external-diff-save-env later to maint).
+
+ * There were many places the code relied on the string returned from
+ getenv() to be non-volatile, which is not true, that have been
+ corrected.
+ (merge 0da0e9268b jk/save-getenv-result later to maint).
+
+ * The v2 upload-pack protocol implementation failed to honor
+ hidden-ref configuration, which has been corrected.
+ (merge e20b4192a3 jk/proto-v2-hidden-refs-fix later to maint).
+
+ * "git fetch --recurse-submodules" may not fetch the necessary commit
+ that is bound to the superproject, which is getting corrected.
+ (merge be76c21282 sb/submodule-recursive-fetch-gets-the-tip later to maint).
+
+ * "git rebase" internally runs "checkout" to switch between branches,
+ and the command used to call the post-checkout hook, but the
+ reimplementation stopped doing so, which is getting fixed.
+
+ * "git add -e" got confused when the change it wants to let the user
+ edit is smaller than the previous change that was left over in a
+ temporary file.
+ (merge fa6f225e01 js/add-e-clear-patch-before-stating later to maint).
+
+ * "git p4" failed to update a shelved change when there were moved
+ files, which has been corrected.
+ (merge 7a10946ab9 ld/git-p4-shelve-update-fix later to maint).
+
+ * The codepath to read from the commit-graph file attempted to read
+ past the end of it when the file's table-of-contents was corrupt.
+
+ * The compat/obstack code had casts that -Wcast-function-type
+ compilation option found questionable.
+ (merge 764473d257 sg/obstack-cast-function-type-fix later to maint).
+
+ * An obvious typo in an assertion error message has been fixed.
+ (merge 3c27e2e059 cc/test-ref-store-typofix later to maint).
+
+ * In Git for Windows, "git clone \\server\share\path" etc. that uses
+ UNC paths from command line had bad interaction with its shell
+ emulation.
+
+ * "git add --ignore-errors" did not work as advertised and instead
+ worked as an unintended synonym for "git add --renormalize", which
+ has been fixed.
+ (merge e2c2a37545 jk/add-ignore-errors-bit-assignment-fix later to maint).
+
+ * On a case-insensitive filesystem, we failed to compare the part of
+ the path that is above the worktree directory in an absolute
+ pathname, which has been corrected.
+
+ * Asking "git check-attr" about a macro (e.g. "binary") on a specific
+ path did not work correctly, even though "git check-attr -a" listed
+ such a macro correctly. This has been corrected.
+ (merge 7b95849be4 jk/attr-macro-fix later to maint).
+
+ * "git pack-objects" incorrectly used uninitialized mutex, which has
+ been corrected.
+ (merge edb673cf10 ph/pack-objects-mutex-fix later to maint).
+
+ * "git checkout -b <new> [HEAD]" to create a new branch from the
+ current commit and check it out ought to be a no-op in the index
+ and the working tree in normal cases, but there are corner cases
+ that do require updates to the index and the working tree. Running
+ it immediately after "git clone --no-checkout" is one of these
+ cases that an earlier optimization kicked in incorrectly, which has
+ been fixed.
+ (merge 8424bfd45b bp/checkout-new-branch-optim later to maint).
+
+ * "git diff --color-moved --cc --stat -p" did not work well due to
+ funny interaction between a bug in color-moved and the rest, which
+ has been fixed.
+ (merge dac03b5518 jk/diff-cc-stat-fixes later to maint).
+
+ * When GIT_SEQUENCE_EDITOR is set, the command was incorrectly
+ started when modes of "git rebase" that implicitly uses the
+ machinery for the interactive rebase are run, which has been
+ corrected.
+ (merge 891d4a0313 pw/no-editor-in-rebase-i-implicit later to maint).
+
+ * The commit-graph facility did not work when in-core objects that
+ are promoted from unknown type to commit (e.g. a commit that is
+ accessed via a tag that refers to it) were involved, which has been
+ corrected.
+ (merge 4468d4435c sg/object-as-type-commit-graph-fix later to maint).
+
+ * "git fetch" output cleanup.
+ (merge dc40b24df4 nd/fetch-compact-update later to maint).
+
+ * "git cat-file --batch" reported a dangling symbolic link by
+ mistake, when it wanted to report that a given name is ambiguous.
+
+ * Documentation around core.crlf has been updated.
+ (merge c9446f0504 jk/autocrlf-overrides-eol-doc later to maint).
+
+ * The documentation of "git commit-tree" said that the command
+ understands "--gpg-sign" in addition to "-S", but the command line
+ parser did not know about the longhand, which has been corrected.
+
+ * "git rebase -x $cmd" did not reject multi-line command, even though
+ the command is incapable of handling such a command. It now is
+ rejected upfront.
+ (merge c762aada1a pw/rebase-x-sanity-check later to maint).
+
+ * Output from "git help" was not correctly aligned, which has been
+ fixed.
+ (merge 6195a76da4 nd/help-align-command-desc later to maint).
+
+ * The "git submodule summary" subcommand showed shortened commit
+ object names by mechanically truncating them at 7-hexdigit, which
+ has been improved to let "rev-parse --short" scale the length of
+ the abbreviation with the size of the repository.
+ (merge 0586a438f6 sh/submodule-summary-abbrev-fix later to maint).
+
+ * The way the OSX build jobs updates its build environment used the
+ "--quiet" option to "brew update" command, but it wasn't all that
+ quiet to be useful. The use of the option has been replaced with
+ an explicit redirection to the /dev/null (which incidentally would
+ have worked around a breakage by recent updates to homebrew, which
+ has fixed itself already).
+ (merge a1ccaedd62 sg/travis-osx-brew-breakage-workaround later to maint).
+
+ * "git --work-tree=$there --git-dir=$here describe --dirty" did not
+ work correctly as it did not pay attention to the location of the
+ worktree specified by the user by mistake, which has been
+ corrected.
+ (merge c801170b0c ss/describe-dirty-in-the-right-directory later to maint).
+
+ * "git fetch" over protocol v2 that needs to make a second connection
+ to backfill tags did not clear a variable that holds shallow
+ repository information correctly, leading to an access of freed
+ piece of memory.
+
+ * Some errors from the other side coming over smart HTTP transport
+ were not noticed, which has been corrected.
+
* Code cleanup, docfix, build fix, etc.
+ (merge 89ba9a79ae hb/t0061-dot-in-path-fix later to maint).
+ (merge d173e799ea sb/diff-color-moved-config-option-fixup later to maint).
+ (merge a8f5a59067 en/directory-renames-nothanks-doc-update later to maint).
+ (merge ec36c42a63 nd/indentation-fix later to maint).
+ (merge f116ee21cd do/gitweb-strict-export-conf-doc later to maint).
+ (merge 112ea42663 fd/gitweb-snapshot-conf-doc-fix later to maint).
+ (merge 1cadad6f65 tb/use-common-win32-pathfuncs-on-cygwin later to maint).
+ (merge 57e9dcaa65 km/rebase-doc-typofix later to maint).
+ (merge b8b4cb27e6 ds/gc-doc-typofix later to maint).
+ (merge 3b3357626e nd/style-opening-brace later to maint).
+ (merge b4583d5595 es/doc-worktree-guessremote-config later to maint).
+ (merge cce99cd8c6 ds/commit-graph-assert-missing-parents later to maint).
+ (merge 0650614982 cy/completion-typofix later to maint).
+ (merge 6881925ef5 rs/sha1-file-close-mapped-file-on-error later to maint).
+ (merge bd8d6f0def en/show-ref-doc-fix later to maint).
+ (merge 1747125e2c cc/partial-clone-doc-typofix later to maint).
+ (merge e01378753d cc/fetch-error-message-fix later to maint).
+ (merge 54e8c11215 jk/remote-insteadof-cleanup later to maint).
+ (merge d609615f48 js/test-git-installed later to maint).
+ (merge ba170517be ja/doc-style-fix later to maint).
+ (merge 86fb1c4e77 km/init-doc-typofix later to maint).
+ (merge 5cfd4a9d10 nd/commit-doc later to maint).
+ (merge 9fce19a431 ab/diff-tree-doc-fix later to maint).
+ (merge 2e285e7803 tz/gpg-test-fix later to maint).
+ (merge 5427de960b kl/pretty-doc-markup-fix later to maint).
+ (merge 3815f64b0d js/mingw-host-cpu later to maint).
+ (merge 5fe81438b5 rj/sequencer-sign-off-header-static later to maint).
+ (merge 18a4f6be6b nd/fileno-may-be-macro later to maint).
+ (merge 99e9ab54ab kd/t0028-octal-del-is-377-not-777 later to maint).