Log Message:
git: updated to 2.15.0

Git 2.15 Release Notes

Backward compatibility notes and other notable changes.

 * Use of an empty string as a pathspec element that is used for
   'everything matches' is still warned and Git asks users to use a
   more explicit '.' for that instead.  The hope is that existing
   users will not mind this change, and eventually the warning can be
   turned into a hard error, upgrading the deprecation into removal of
   this (mis)feature.  That is now scheduled to happen in Git v2.16,
   the next major release after this one.

 * Git now avoids blindly falling back to ".git" when the setup
   sequence said we are _not_ in Git repository.  A corner case that
   happens to work right now may be broken by a call to BUG().
   We've tried hard to locate such cases and fixed them, but there
   might still be cases that need to be addressed--bug reports are
   greatly appreciated.

 * "branch --set-upstream" that has been deprecated in Git 1.8 has
   finally been retired.

Updates since v2.14
-------------------

UI, Workflows & Features

 * An example that is now obsolete has been removed from a sample hook,
   and an old example in it that added a sign-off manually has been
   improved to use the interpret-trailers command.

 * The advice message given when "git rebase" stops for conflicting
   changes has been improved.

 * The "rerere-train" script (in contrib/) learned the \ 
"--overwrite"
   option to allow overwriting existing recorded resolutions.

 * "git contacts" (in contrib/) now lists the address on the
   "Reported-by:" trailer to its output, in addition to those on
   S-o-b: and other trailers, to make it easier to notify (and thank)
   the original bug reporter.

 * "git rebase", especially when it is run by mistake and ends up
   trying to replay many changes, spent long time in silence.  The
   command has been taught to show progress report when it spends
   long time preparing these many changes to replay (which would give
   the user a chance to abort with ^C).

 * "git merge" learned a "--signoff" option to add the \ 
Signed-off-by:
   trailer with the committer's name.

 * "git diff" learned to optionally paint new lines that are the same
   as deleted lines elsewhere differently from genuinely new lines.

 * "git interpret-trailers" learned to take the trailer specifications
   from the command line that overrides the configured values.

 * "git interpret-trailers" has been taught a "--parse" and a few
   other options to make it easier for scripts to grab existing
   trailer lines from a commit log message.

 * The "--format=%(trailers)" option "git log" and its \ 
friends take
   learned to take the 'unfold' and 'only' modifiers to normalize its
   output, e.g. "git log --format=%(trailers:only,unfold)".

 * "gitweb" shows a link to visit the 'raw' contents of blbos in the
   history overview page.

 * "[gc] rerereResolved = 5.days" used to be invalid, as the variable
   is defined to take an integer counting the number of days.  It now
   is allowed.

 * The code to acquire a lock on a reference (e.g. while accepting a
   push from a client) used to immediately fail when the reference is
   already locked---now it waits for a very short while and retries,
   which can make it succeed if the lock holder was holding it during
   a read-only operation.

 * "branch --set-upstream" that has been deprecated in Git 1.8 has
   finally been retired.

 * The codepath to call external process filter for smudge/clean
   operation learned to show the progress meter.

 * "git rev-parse" learned "--is-shallow-repository", that \ 
is to be
   used in a way similar to existing "--is-bare-repository" and
   friends.

 * "git describe --match <pattern>" has been taught to play well with
   the "--all" option.

 * "git branch" learned "-c/-C" to create a new branch by \ 
copying an
   existing one.

 * Some commands (most notably "git status") makes an opportunistic
   update when performing a read-only operation to help optimize later
   operations in the same repository.  The new "--no-optional-locks"
   option can be passed to Git to disable them.

 * "git for-each-ref --format=..." learned a new format element,
   %(trailers), to show only the commit log trailer part of the log
   message.

Performance, Internal Implementation, Development Support etc.

...more...