Case #3 is slightly tricky and needs explanation. The result from this
rule logically should be to remove the path if the user staged the removal
-of the path and then swiching to a new branch. That however will prevent
+of the path and then switching to a new branch. That however will prevent
the initial checkout from happening, so the rule is modified to use M (new
tree) only when the contents of the index is empty. Otherwise the removal
of the path is kept as long as $H and $M are the same.