diff -r 04cc9c32f3e3 Lib/unittest/mock.py
--- a/Lib/unittest/mock.py	Thu Jun 12 18:39:42 2014 +0200
+++ b/Lib/unittest/mock.py	Thu Jun 12 13:37:29 2014 -0400
@@ -2303,7 +2303,13 @@
                 yield handle.readline.return_value
         for line in _data:
             yield line
-
+        while True:
+            yield ''
+
+    def _iter_side_effect():
+        if handle.__iter__.return_value is not None:
+            return handle.__iter__.return_value
+        return _data
 
     global file_spec
     if file_spec is None:
@@ -2322,10 +2328,12 @@
     handle.read.return_value = None
     handle.readline.return_value = None
     handle.readlines.return_value = None
+    handle.__iter__.return_value = None
 
     handle.read.side_effect = _read_side_effect
     handle.readline.side_effect = _readline_side_effect()
     handle.readlines.side_effect = _readlines_side_effect
+    handle.__iter__.side_effect = _iter_side_effect
 
     mock.return_value = handle
     return mock