Log Message:
git: updated to 2.15.1

Git v2.15.1 Release Notes

Fixes since v2.15
-----------------

 * TravisCI build updates.

 * "auto" as a value for the columnar output configuration ought to
   judge "is the output consumed by humans?" with the same criteria as
   "auto" for coloured output configuration, i.e. either the standard
   output stream is going to tty, or a pager is in use.  We forgot the
   latter, which has been fixed.

 * The experimental "color moved lines differently in diff output"
   feature was buggy around "ignore whitespace changes" edges, which
   has been corrected.

 * Instead of using custom line comparison and hashing functions to
   implement "moved lines" coloring in the diff output, use the pair
   of these functions from lower-layer xdiff/ code.

 * Some codepaths did not check for errors when asking what branch the
   HEAD points at, which have been fixed.

 * "git commit", after making a commit, did not check for errors when
   asking on what branch it made the commit, which has been corrected.

 * "git status --ignored -u" did not stop at a working tree of a
   separate project that is embedded in an ignored directory and
   listed files in that other project, instead of just showing the
   directory itself as ignored.

 * A broken access to object databases in recent update to "git grep
   --recurse-submodules" has been fixed.

 * A recent regression in "git rebase -i" that broke execution of git
   commands from subdirectories via "exec" instruction has been fixed.

 * "git check-ref-format --branch @{-1}" bit a "BUG()" when run
   outside a repository for obvious reasons; clarify the documentation
   and make sure we do not even try to expand the at-mark magic in
   such a case, but still call the validation logic for branch names.

 * Command line completion (in contrib/) update.

 * Description of blame.{showroot,blankboundary,showemail,date}
   configuration variables have been added to "git config --help".

 * After an error from lstat(), diff_populate_filespec() function
   sometimes still went ahead and used invalid data in struct stat,
   which has been fixed.

 * UNC paths are also relevant in Cygwin builds and they are now
   tested just like Mingw builds.

 * Correct start-up sequence so that a repository could be placed
   immediately under the root directory again (which was broken at
   around Git 2.13).

 * The credential helper for libsecret (in contrib/) has been improved
   to allow possibly prompting the end user to unlock secrets that are
   currently locked (otherwise the secrets may not be loaded).

 * Updates from GfW project.

 * "git rebase -i" recently started misbehaving when a submodule that
   is configured with 'submodule.<name>.ignore' is dirty; this has
   been corrected.

 * Some error messages did not quote filenames shown in it, which have
   been fixed.

 * Building with NO_LIBPCRE1_JIT did not disable it, which has been fixed.

 * We used to add an empty alternate object database to the system
   that does not help anything; it has been corrected.

 * Error checking in "git imap-send" for empty response has been
   improved.

 * An ancient bug in "git apply --ignore-space-change" codepath has
   been fixed.

 * There was a recent semantic mismerge in the codepath to write out a
   section of a configuration section, which has been corrected.