diff -r c0e63937efa7 Lib/subprocess.py
--- a/Lib/subprocess.py	Wed Nov 20 00:14:49 2013 +0100
+++ b/Lib/subprocess.py	Wed Nov 20 01:02:49 2013 +0100
@@ -1555,6 +1555,10 @@ class Popen(object):
 
             self._save_input(input)
 
+            # use a memoryview to avoid memory copies
+            if input:
+                input_view = memoryview(self._input)
+
             with _PopenSelector() as selector:
                 if self.stdin and input:
                     selector.register(self.stdin, selectors.EVENT_WRITE)
@@ -1576,8 +1580,8 @@ class Popen(object):
 
                     for key, events in ready:
                         if key.fileobj is self.stdin:
-                            chunk = self._input[self._input_offset :
-                                                self._input_offset + _PIPE_BUF]
+                            chunk = input_view[self._input_offset :
+                                               self._input_offset + _PIPE_BUF]
                             try:
                                 self._input_offset += os.write(key.fd, chunk)
                             except OSError as e:
diff -r c0e63937efa7 Objects/listobject.c
--- a/Objects/listobject.c	Wed Nov 20 00:14:49 2013 +0100
+++ b/Objects/listobject.c	Wed Nov 20 01:02:49 2013 +0100
@@ -2483,6 +2483,7 @@ list_ass_subscript(PyListObject* self, P
             PyObject **garbage;
             size_t cur;
             Py_ssize_t i;
+            int res;
 
             if (slicelength <= 0)
                 return 0;
@@ -2533,14 +2534,14 @@ list_ass_subscript(PyListObject* self, P
             }
 
             Py_SIZE(self) -= slicelength;
-            list_resize(self, Py_SIZE(self));
+            res = list_resize(self, Py_SIZE(self));
 
             for (i = 0; i < slicelength; i++) {
                 Py_DECREF(garbage[i]);
             }
             PyMem_FREE(garbage);
 
-            return 0;
+            return res;
         }
         else {
             /* assign slice */