The sixth batch

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/RelNotes/2.31.0.txt

@@ -48,6 +48,13 @@ UI, Workflows & Features
    standard input.  Also, it now does not lose refs whey they point
    at the same object.
 
+ * "git log" learned a new "--diff-merges=<how>" option.
+
+ * "git ls-files" can and does show multiple entries when the index is
+   unmerged, which is a source for confusion unless -s/-u option is in
+   use.  A new option --deduplicate has been introduced.
+
+
 Performance, Internal Implementation, Development Support etc.
 
  * A 3-year old test that was not testing anything useful has been
@@ -80,6 +87,38 @@ Performance, Internal Implementation, Development Support etc.
  * The .use_shell flag in struct child_process that is passed to
    run_command() API has been clarified with a bit more documentation.
 
+ * Document, clean-up and optimize the code around the cache-tree
+   extension in the index.
+
+ * The ls-refs protocol operation has been optimized to narrow the
+   sub-hierarchy of refs/ it walks to produce response.
+
+ * When removing many branches and tags, the code used to do so one
+   ref at a time.  There is another API it can use to delete multiple
+   refs, and it makes quite a lot of performance difference when the
+   refs are packed.
+
+ * The "pack-objects" command needs to iterate over all the tags when
+   automatic tag following is enabled, but it actually iterated over
+   all refs and then discarded everything outside "refs/tags/"
+   hierarchy, which was quite wasteful.
+
+ * A perf script was made more portable.
+   (merge f08b6c553d jk/p5303-sed-portability-fix later to maint).
+
+ * Our setting of GitHub CI test jobs were a bit too eager to give up
+   once there is even one failure found.  Tweak the knob to allow
+   other jobs keep running even when we see a failure, so that we can
+   find more failures in a single run.
+   (merge 2b0e14f640 pb/ci-matrix-wo-shortcut later to maint).
+
+ * We've carried compatibility codepaths for compilers without
+   variadic macros for quite some time, but the world may be ready for
+   them to be removed.  Force compilation failure on exotic platforms
+   where variadic macros are not available to find out who screams in
+   such a way that we can easily revert if it turns out that the world
+   is not yet ready.
+
 
 Fixes since v2.30
 -----------------
@@ -159,3 +198,4 @@ Fixes since v2.30
    (merge a4a1ca22ef tb/local-clone-race-doc later to maint).
    (merge 6a8c89d053 ma/more-opaque-lock-file later to maint).
    (merge 4a5ec7d166 js/skip-dashed-built-ins-from-config-mak later to maint).
+   (merge 6eaf624dea pb/blame-funcname-range-userdiff later to maint).