Sync with maint

* maint:
  Preparation for 2.13.4 continues

Documentation/RelNotes/2.13.4.txt

@@ -8,3 +8,21 @@ Fixes since v2.13.3
 
  * A recent update broke an alias that contained an uppercase letter,
    which has been fixed.
+
+ * On Cygwin, similar to Windows, "git push //server/share/repository"
+   ought to mean a repository on a network share that can be accessed
+   locally, but this did not work correctly due to stripping the double
+   slashes at the beginning.
+
+ * The progress meter did not give a useful output when we haven't had
+   0.5 seconds to measure the throughput during the interval.  Instead
+   show the overall throughput rate at the end, which is a much more
+   useful number.
+
+ * We run an early part of "git gc" that deals with refs before
+   daemonising (and not under lock) even when running a background
+   auto-gc, which caused multiple gc processes attempting to run the
+   early part at the same time.  This is now prevented by running the
+   early part also under the GC lock.
+
+Also contains a handful of small code and documentation clean-ups.