Fixes since v1.8.4.1
--------------------
+ * "git branch --track" had a minor regression in v1.8.3.2 and later
+ that made it impossible to base your local work on anything but a
+ local branch of the upstream repository you are tracking from.
+
+ * "git ls-files -k" needs to crawl only the part of the working tree
+ that may overlap the paths in the index to find killed files, but
+ shared code with the logic to find all the untracked files, which
+ made it unnecessarily inefficient.
+
+ * When there is no sufficient overlap between old and new history
+ during a "git fetch" into a shallow repository, objects that the
+ sending side knows the receiving end has were unnecessarily sent.
+
* When running "fetch -q", a long silence while the sender side
computes the set of objects to send can be mistaken by proxies as
dropped connection. The server side has been taught to send a