Log Message:
Git v2.13.4:

* Update the character width tables.

* 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.