SPEC in rack-1.4.1 vs SPEC in rack-1.4.2

@@ -154,10 +154,12 @@
 === The Body
 The Body must respond to +each+
 and must only yield String values.
 The Body itself should not be an instance of String, as this will
 break in Ruby 1.9.
-If the Body responds to +close+, it will be called after iteration.
+If the Body responds to +close+, it will be called after iteration. If
+the body is replaced by a middleware after action, the original body
+must be closed first, if it repsonds to close.
 If the Body responds to +to_path+, it must return a String
 identifying the location of a file whose contents are identical
 to that produced by calling +each+; this may be used by the
 server as an alternative, possibly more efficient way to
 transport the response.