Git 2.18 Release Notes
======================

Updates since v2.17
-------------------

UI, Workflows & Features

 * Rename detection logic in "diff" family that is used in "merge" has
   learned to guess when all of x/a, x/b and x/c have moved to z/a,
   z/b and z/c, it is likely that x/d added in the meantime would also
   want to move to z/d by taking the hint that the entire directory
   'x' moved to 'z'.  A bug causing dirty files involved in a rename
   to be overwritten during merge has also been fixed as part of this
   work.

 * "git filter-branch" learned to use a different exit code to allow
   the callers to tell the case where there was no new commits to
   rewrite from other error cases.



Performance, Internal Implementation, Development Support etc.

 * A "git fetch" from a repository with insane number of refs into a
   repository that is already up-to-date still wasted too many cycles
   making many lstat(2) calls to see if these objects at the tips
   exist as loose objects locally.  These lstat(2) calls are optimized
   away by enumerating all loose objects beforehand.
   It is unknown if the new strategy negatively affects existing use
   cases, fetching into a repository with many loose objects from a
   repository with small number of refs.

 * Git can be built to use either v1 or v2 of the PCRE library, and so
   far, the build-time configuration USE_LIBPCRE=YesPlease instructed
   the build procedure to use v1, but now it means v2.  USE_LIBPCRE1
   and USE_LIBPCRE2 can be used to explicitly choose which version to
   use, as before.

 * The build procedure learned to optionally use symbolic links
   (instead of hardlinks and copies) to install "git-foo" for built-in
   commands, whose binaries are all identical.

 * Conversion from uchar[20] to struct object_id continues.

 * The way "git worktree prune" worked internally has been simplified,
   by assuming how "git worktree move" moves an existing worktree to a
   different place.

Also contains various documentation updates and code clean-ups.


Fixes since v2.17
-----------------

 * "git shortlog cruft" aborted with a BUG message when run outside a
   Git repository.  The command has been taught to complain about
   extra and unwanted arguments on its command line instead in such a
   case.
   (merge 4aa0161e83 ma/shortlog-revparse later to maint).

 * "git stash push -u -- <pathspec>" gave an unnecessary and confusing
   error message when there was no tracked files that match the
   <pathspec>, which has been fixed.
   (merge 353278687e tg/stash-untracked-with-pathspec-fix later to maint).

 * Other minor doc, test and build updates and code cleanups.
